WM8903CLGEFK/R [WOLFSON]
Ultra Low Power CODEC for Portable Audio Applications; 超低功耗编解码器用于便携式音频应用
| 型号： | WM8903CLGEFK/R |
| 厂家： | 
WOLFSON MICROELECTRONICS PLC |
| 描述： | Ultra Low Power CODEC for Portable Audio Applications |
| 文件： | 总178页 (文件大小：1387K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
WM8903
w
Ultra Low Power CODEC for Portable Audio Applications
DESCRIPTION
FEATURES
4.5mW power consumption for DAC to headphone
playback
The WM8903 is a high performance ultra-low power stereo
CODEC optimised for portable audio applications.
DAC SNR 96dB typical, THD -86dB typical
ADC SNR 92dB typical, THD -80dB typical
The device features stereo ground-referenced headphone
amplifiers using the Wolfson ‘Class W’ amplifier techniques -
incorporating an innovative dual-mode charge pump
architecture - to optimise efficiency and power consumption
during playback. The ground-referenced outputs eliminate
headphone coupling capacitors. Both headphone and line
outputs include common mode feedback paths to reject
ground noise.
Control sequencer for pop minimised start-up and shut-
down
Single register write for default start-up sequence
Integrated FLL provides all necessary clocks
Control sequences for audio path setup can be pre-loaded
and executed by an integrated sequencer to reduce
software driver development and eliminate pops and clicks
via Wolfson’s SilentSwitch™ technology.
-
Self-clocking modes allow processor to sleep
All standard sample rates from 8kHz to 96kHz
-
Stereo digital microphone input
The analogue input stage can be configured for single
ended or differential inputs. Up to 3 stereo microphone or
line inputs may be connected. The input impedance is
constant with PGA gain setting.
3 single ended inputs per stereo channel
1 fully differential mic / line input per stereo channel
Digital Dynamic Range Controller (compressor / limiter)
Digital sidetone mixing
A stereo digital microphone interface is provided, which can
also be mixed with the mic/line signals at the output mixers.
A dynamic range controller provides compression and level
control to support a wide range of portable recording
applications. Anti-clip and quick release features offer good
performance in the presence of loud impulsive noises.
Ground-referenced headphone driver
Ground-referenced line outputs
Stereo differential line driver for direct interface to WM9001
speaker driver
Common audio sampling frequencies are supported from a
range of external clocks, either directly or generated via the
Frequency Locked Loop (FLL).
40-pin QFN package (5x5mm)
The WM8903 can operate directly from a single 1.8V
switched supply. For optimal power consumption, the digital
core can be operated from a 1.0V supply.
APPLICATIONS
Portable multimedia players
Multimedia handsets
Handheld gaming
WOLFSON MICROELECTRONICS plc
Production Data, June 2012, Rev 4.5
Copyright 2012 Wolfson Microelectronics plc
To receive regular email updates, sign up at http://www.wolfsonmicro.com/enews
WM8903
Production Data
BLOCK DIAGRAM
DGND
DCVDD
DBVDD
CPGND CFB1
CFB2 CPVDD
VPOS
CHARGE PUMP
VNEG
WM8903
IN1L
+
M
U
X
PGA
+ MIC
(headphone / line output)
HPOUTL
IN2L
IN3L
BOOST
-
DYNAMIC
LEFT MIXER
HPOUTL_VOL
ADC
ADC
RANGE
HPGND
DAC
CONTROL
DIGITAL
FILTERS
Stereo
Digital
Mic
VOLUME
DMIC_LR / GPIO1
DMIC_DAT / GPIO2
HPOUTR
VOLUME
DIGITAL
Interface
HPOUTR_VOL
LINEOUTL_VOL
MONO MIX
DIGITAL
(headphone / line output)
LINEOUTL
MONO MIX
RIGHT MIXER
DIGITAL
DAC
SIDE TONE
IN1R
IN2R
IN3R
+
PGA
+ MIC
M
U
X
LINEGND
BOOST
-
LINEOUTR
LINEOUTR_VOL
SPKR_VOL
LEFT SPKR MIXER
RIGHT SPKR MIXER
(differential line output)
LOP
LON
MICBIAS
ROP
RON
CONTROL
INTERFACE
AUDIO
INTERFACE
FLL / CLOCK
CIRCUITRY
VMID
Reference
SPKR_VOL
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WM8903
TABLE OF CONTENTS
DESCRIPTION....................................................................................................... 1
FEATURES............................................................................................................ 1
APPLICATIONS..................................................................................................... 1
BLOCK DIAGRAM ................................................................................................ 2
TABLE OF CONTENTS......................................................................................... 3
PIN CONFIGURATION.......................................................................................... 6
ORDERING INFORMATION.................................................................................. 6
PIN DESCRIPTION................................................................................................ 7
ABSOLUTE MAXIMUM RATINGS........................................................................ 8
RECOMMENDED OPERATING CONDITIONS..................................................... 8
ELECTRICAL CHARACTERISTICS ..................................................................... 9
TERMINOLOGY............................................................................................................... 9
COMMON TEST CONDITIONS....................................................................................... 9
INPUT SIGNAL PATH.................................................................................................... 10
OUTPUT SIGNAL PATH................................................................................................ 12
BYPASS PATH .............................................................................................................. 14
CHARGE PUMP............................................................................................................. 15
FLL ................................................................................................................................. 15
OTHER PARAMETERS ................................................................................................. 15
POWER CONSUMPTION.................................................................................... 17
COMMON TEST CONDITIONS..................................................................................... 17
POWER CONSUMPTION MEASUREMENTS............................................................... 17
SIGNAL TIMING REQUIREMENTS .................................................................... 19
COMMON TEST CONDITIONS..................................................................................... 19
MASTER CLOCK........................................................................................................... 19
AUDIO INTERFACE TIMING ......................................................................................... 20
MASTER MODE .............................................................................................................................................................. 20
SLAVE MODE.................................................................................................................................................................. 21
TDM MODE ..................................................................................................................................................................... 22
CONTROL INTERFACE TIMING................................................................................... 23
DIGITAL FILTER CHARACTERISTICS .............................................................. 24
DAC FILTER RESPONSES ........................................................................................... 25
ADC FILTER RESPONSES ........................................................................................... 26
ADC HIGH PASS FILTER RESPONSES....................................................................... 27
DE-EMPHASIS FILTER RESPONSES.......................................................................... 28
DEVICE DESCRIPTION ...................................................................................... 29
INTRODUCTION............................................................................................................ 29
ANALOGUE INPUT SIGNAL PATH............................................................................... 30
INPUT PGA ENABLE ...................................................................................................................................................... 31
INPUT PGA CONFIGURATION ...................................................................................................................................... 31
SINGLE-ENDED INPUT .................................................................................................................................................. 33
DIFFERENTIAL LINE INPUT........................................................................................................................................... 33
DIFFERENTIAL MICROPHONE INPUT.......................................................................................................................... 34
INPUT PGA GAIN CONTROL ......................................................................................................................................... 34
INPUT PGA COMMON MODE AMPLIFIER.................................................................................................................... 36
ELECTRET CONDENSER MICROPHONE INTERFACE.............................................. 37
MICBIAS CURRENT DETECT ........................................................................................................................................ 37
MICBIAS CURRENT DETECT FILTERING .................................................................................................................... 38
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MICROPHONE HOOK SWITCH DETECTION................................................................................................................ 39
DIGITAL MICROPHONE INTERFACE .......................................................................... 40
ANALOGUE-TO-DIGITAL CONVERTER (ADC)............................................................ 42
ADC DIGITAL VOLUME CONTROL................................................................................................................................ 42
HIGH-PASS FILTER (HPF) ............................................................................................................................................. 45
ADC OVERSAMPLING RATIO (OSR) ............................................................................................................................ 46
DYNAMIC RANGE CONTROL (DRC) ........................................................................... 46
COMPRESSION/LIMITING CAPABILITIES .................................................................................................................... 46
GAIN LIMITS.................................................................................................................................................................... 48
DYNAMIC CHARACTERISTICS ..................................................................................................................................... 49
ANTI-CLIP CONTROL..................................................................................................................................................... 50
QUICK RELEASE CONTROL ......................................................................................................................................... 50
GAIN SMOOTHING......................................................................................................................................................... 51
INITIALISATION .............................................................................................................................................................. 52
DIGITAL MIXING............................................................................................................ 53
DIGITAL MIXING PATHS ................................................................................................................................................ 53
DAC INTERFACE VOLUME BOOST .............................................................................................................................. 54
DIGITAL SIDETONE........................................................................................................................................................ 55
DIGITAL-TO-ANALOGUE CONVERTER (DAC)............................................................ 56
DAC DIGITAL VOLUME CONTROL................................................................................................................................ 57
DAC SOFT MUTE AND SOFT UN-MUTE....................................................................................................................... 59
DAC MONO MIX.............................................................................................................................................................. 60
DAC DE-EMPHASIS........................................................................................................................................................ 60
DAC SLOPING STOPBAND FILTER .............................................................................................................................. 61
DAC BIAS CONTROL...................................................................................................................................................... 61
DAC OVERSAMPLING RATIO (OSR) ............................................................................................................................ 62
OUTPUT SIGNAL PATH................................................................................................ 63
OUTPUT SIGNAL PATHS ENABLE................................................................................................................................ 64
HEADPHONE / LINE OUTPUT SIGNAL PATHS ENABLE............................................................................................. 65
OUTPUT PGA BIAS CONTROL...................................................................................................................................... 68
OUTPUT DRIVERS BIAS CONTROL ............................................................................................................................. 68
OUTPUT MIXER CONTROL ........................................................................................................................................... 69
OUTPUT VOLUME CONTROL ....................................................................................................................................... 71
ANALOGUE OUTPUTS ................................................................................................. 75
HEADPHONE OUTPUTS – HPOUTL AND HPOUTR..................................................................................................... 75
LINE OUTPUTS – LINEOUTL AND LINEOUTR ............................................................................................................. 75
DIFFERENTIAL LINE OUTPUTS – LON/LOP AND RON/ROP ...................................................................................... 75
EXTERNAL COMPONENTS FOR GROUND-REFERENCED OUTPUTS...................................................................... 76
REFERENCE VOLTAGES AND MASTER BIAS ........................................................... 77
POP SUPPRESSION CONTROL .................................................................................. 79
DISABLED INPUT / OUTPUT CONTROL....................................................................................................................... 79
DIFFERENTIAL LINE OUTPUT DISCHARGE CONTROL.............................................................................................. 79
CHARGE PUMP............................................................................................................. 80
DC SERVO.....................................................................................................................81
DIGITAL AUDIO INTERFACE........................................................................................ 84
MASTER AND SLAVE MODE OPERATION................................................................................................................... 84
OPERATION WITH TDM................................................................................................................................................. 85
BCLK FREQUENCY........................................................................................................................................................ 86
AUDIO DATA FORMATS (NORMAL MODE).................................................................................................................. 86
AUDIO DATA FORMATS (TDM MODE) ......................................................................................................................... 88
DIGITAL AUDIO INTERFACE CONTROL ..................................................................... 90
BCLK AND LRCLK CONTROL........................................................................................................................................ 91
COMPANDING ................................................................................................................................................................ 93
LOOPBACK ..................................................................................................................................................................... 94
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WM8903
CLOCKING AND SAMPLE RATES................................................................................ 95
CLK_SYS CONTROL ...................................................................................................................................................... 97
CONTROL INTERFACE CLOCKING .............................................................................................................................. 98
AUTOMATIC CLOCKING CONFIGURATION................................................................................................................. 98
USB CLOCKING MODE................................................................................................................................................ 100
ADC / DAC OPERATION AT 88.2K / 96K ..................................................................................................................... 100
DIGITAL MICROPHONE (DMIC) OPERATION ............................................................................................................ 101
FREQUENCY LOCKED LOOP (FLL)........................................................................... 101
FREE-RUNNING FLL CLOCK....................................................................................................................................... 105
GPIO OUTPUTS FROM FLL......................................................................................................................................... 105
EXAMPLE FLL CALCULATION..................................................................................................................................... 105
EXAMPLE FLL SETTINGS............................................................................................................................................ 106
GENERAL PURPOSE INPUT/OUTPUT (GPIO).......................................................... 107
INTERRUPTS .............................................................................................................. 112
CONTROL INTERFACE............................................................................................... 115
CONTROL WRITE SEQUENCER................................................................................ 118
INITIATING A SEQUENCE............................................................................................................................................ 118
PROGRAMMING A SEQUENCE .................................................................................................................................. 119
DEFAULT SEQUENCES............................................................................................................................................... 122
START-UP SEQUENCE................................................................................................................................................ 122
SHUTDOWN SEQUENCE............................................................................................................................................. 125
POWER-ON RESET .................................................................................................... 127
QUICK START-UP AND SHUTDOWN ........................................................................ 129
QUICK START-UP (DEFAULT SEQUENCE)................................................................................................................ 129
QUICK SHUTDOWN (DEFAULT SEQUENCE) ............................................................................................................ 129
SOFTWARE RESET AND CHIP ID ............................................................................. 130
REGISTER MAP................................................................................................ 131
REGISTER BITS BY ADDRESS.................................................................................. 134
APPLICATIONS INFORMATION ...................................................................... 172
RECOMMENDED EXTERNAL COMPONENTS.......................................................... 172
MIC DETECTION SEQUENCE USING MICBIAS CURRENT ..................................... 174
PACKAGE DIMENSIONS.................................................................................. 176
IMPORTANT NOTICE ....................................................................................... 177
ADDRESS.................................................................................................................... 177
REVISION HISTORY ......................................................................................... 178
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Production Data
PIN CONFIGURATION
ORDERING INFORMATION
MOISTURE
SENSITIVITY LEVEL
PEAK SOLDERING
TEMPERATURE
TEMPERATURE
DEVICE
RANGE
PACKAGE
MSL1
260°C
WM8903CLGEFK
-40°C to +85°C
40-lead QFN
(5x5x0.55mm, lead-free)
40-lead QFN
MSL1
260°C
WM8903CLGEFK/R
-40°C to +85°C
(5x5x0.55mm, lead-free, tape and
reel)
Note:
Tube quantity = 95
Reel quantity = 3,500
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WM8903
PIN DESCRIPTION
PIN
1
NAME
DGND
MCLK
TYPE
DESCRIPTION
Digital ground (return path for DCVDD and DBVDD)
Master clock for CODEC
Supply
Digital Input
2
Digital Input/Output
GPIO2 / Digital microphone data input
3
GPIO2/
DMIC_DAT
Digital Input/Output
GPIO1 / Digital microphone clock output
4
GPIO1/
DMIC_LR
Digital Output
Digital Input/Output
Digital Input
Interrupt output / GPIO4
5
INTERRUPT
BCLK
Audio interface bit clock / GPIO5
DAC digital audio data
6
7
DACDAT
LRC
Digital Input/Output
Digital Output
Supply
Audio interface left / right clock (common for ADC and DAC)
ADC digital audio data
8
9
ADCDAT
CPVDD
CFB1
Charge pump power supply
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Analogue Output
Supply
Charge pump flyback capacitor pin
Charge pump ground
CPGND
CFB2
Analogue Output
Analogue Output
Analogue Output
Analogue Output
Analogue Input
Analogue Output
Analogue Output
Analogue Input
Analogue Output
Analogue Output
Analogue Output
Supply
Charge pump flyback capacitor pin
Charge pump positive supply decoupling (powers HPOUTL/R, LINEOUTL/R)
Charge pump negative supply decoupling (powers HPOUTL/R, LINEOUTL/R)
Right headphone output (line or headphone output)
Headphone ground
VPOS
VNEG
HPOUTR
HPGND
HPOUTL
LINEOUTR
LINEGND
LINEOUTL
LOP
Left headphone output (line or headphone output)
Right line output 1 (line output)
Line-out ground
Left line output 1 (line output)
Left differential output positive side
Left differential output negative side
LON
Analogue power supply (powers analogue inputs, reference, ADC, DAC, LOP,
LON, ROP, RON)
AVDD
Analogue Output
Supply
Midrail voltage decoupling capacitor
Analogue power return
25
26
27
28
29
30
31
32
33
34
35
36
37
38
VMID
AGND
RON
Analogue Output
Analogue Output
Analogue Output
Analogue Input
Analogue Input
Analogue Input
Analogue Input
Analogue Input
Analogue Input
Digital Input/Output
Digital Input
Right differential output negative side
Right differential output positive side
Microphone bias
ROP
MICBIAS
IN3R
Right channel input 3
Right channel input 2
IN2R
Right channel input 1
IN1R
Left channel input 3
IN3L
Left channel input 2
IN2L
Left channel input 1
IN1L
Control interface data Input / 2-wire acknowledge output
Control interface clock Input
GPIO3 / control interface address selection
SDIN
SCLK
Digital Input/Output
GPIO3
/ADDR
Supply
Supply
Digital core supply
39
40
DCVDD
DBVDD
Digital buffer supply (powers audio interface and control interface)
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WM8903
Production Data
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously
operating at or beyond these limits. Device functional operating limits and guaranteed performance specifications are given
under Electrical Characteristics at the test conditions specified.
ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible
to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage
of this device.
Wolfson tests its package types according to IPC/JEDEC J-STD-020B for Moisture Sensitivity to determine acceptable storage
conditions prior to surface mount assembly. These levels are:
MSL1 = unlimited floor life at <30C / 85% Relative Humidity. Not normally stored in moisture barrier bag.
MSL2 = out of bag storage for 1 year at <30C / 60% Relative Humidity. Supplied in moisture barrier bag.
MSL3 = out of bag storage for 168 hours at <30C / 60% Relative Humidity. Supplied in moisture barrier bag.
The Moisture Sensitivity Level for each package type is specified in Ordering Information.
CONDITION
MIN
-0.3V
MAX
+2.5V
AVDD, DCVDD
DBVDD,
-0.3V
+4.5V
CPVDD
-0.3V
+2.2V
HPOUTL, HPOUTR, LINEOUTL, LINEOUTR
Voltage range digital inputs
Voltage range analogue inputs
Temperature range, TA
(CPVDD + 0.3V) * -1
DGND -0.3V
AGND -0.3V
-40C
CPVDD + 0.3
DBVDD +0.3V
AVDD +0.3V
+85C
Storage temperature after soldering
Notes
-65C
+150C
1. Analogue and digital grounds must always be within 0.3V of each other.
2. All digital and analogue supplies are completely independent from each other; there is no restriction on power supply
sequencing.
3. HPOUTL, HPOUTR, LINEOUTL, LINEOUTR are outputs, and should not normally become connected to DC levels.
However, if the limits above are exceeded, then damage to the WM8903 may occur.
RECOMMENDED OPERATING CONDITIONS
PARAMETER
SYMBOL
MIN
0.95
1.42
1.71
1.71
TYP
1.2
1.8
1.8
1.8
0
MAX
1.89
3.6
UNIT
V
Digital supply range (Core)
Digital supply range (Buffer)
Analogue supplies range
Charge pump supply range
Ground
DCVDD
DBVDD
V
AVDD
2.0
V
CPVDD
DGND, AGND, CPGND
TA
2.0
V
V
Operating Temperature (ambient)
-40
+25
+85
C
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WM8903
ELECTRICAL CHARACTERISTICS
TERMINOLOGY
1. Signal-to-Noise Ratio (dB) – SNR is the difference in level between a full scale output signal and the device output
noise with no signal applied, measured over a bandwidth of 20Hz to 20kHz. This ratio is also called idle channel noise.
(No Auto-zero or Automute function is employed).
2. Total Harmonic Distortion (dB) – THD is the difference in level between a 1kHz full scale sinewave output signal and
the first seven harmonics of the output signal. The amplitude of the fundamental frequency of the output signal is
compared to the RMS value of the next seven harmonics and expressed as a ratio.
3. Total Harmonic Distortion + Noise (dB) – THD+N is the difference in level between a 1kHz full scale sine wave output
signal and all noise and distortion products in the audio band. The amplitude of the fundamental reference frequency of
the output signal is compared to the RMS value of all other noise and distortion products and expressed as a ratio.
4. Channel Separation (dB) – is a measure of the coupling between left and right channels. A full scale signal is applied
to the left channel only, the right channel amplitude is measured. Then a full scale signal is applied to the right channel
only and the left channel amplitude is measured. The worst case channel separation is quoted as a ratio.
5. Channel Level Matching (dB) – measures the difference in gain between the left and the right channels.
6. Power Supply Rejection Ratio (dB) – PSRR is a measure of ripple attenuation between the power supply pin and an
output path. With the signal path idle, a small signal sine wave is summed onto the power supply rail, The amplitude of
the sine wave is measured at the output port and expressed as a ratio.
7. All performance measurements carried out with 20kHz AES17 low pass filter for distortion measurements, and an
A-weighted filter for noise measurement. Failure to use such a filter will result in higher THD and lower SNR and
Dynamic Range readings than are found in the Electrical Characteristics. The low pass filter removes out of band
noise; although it is not audible it may affect dynamic specification values.
COMMON TEST CONDITIONS
Unless otherwise stated, the following test conditions apply throughout the following sections:
DCVDD = 1.2V
DBVDD = 1.8V
AVDD = CPVDD =1.8V
Ambient temperature = +25°C
Audio signal: 1kHz sine wave, sampled at 48kHz with 24-bit data resolution
Additional, specific test conditions are given within the relevant sections below.
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INPUT SIGNAL PATH
Single-ended stereo line record - IN1L+IN1R pins to ADC output
Test conditions:
L_MODE = R_MODE = 00b (Single ended)
LIN_VOL = RIN_VOL = 00000b (-1.55dB)
Total signal path gain = 4.45dB, incorporating 6dB single-ended to differential conversion gain
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
0.570
-4.88
1.61
10
TYP
0.600
-4.45
1.70
12
MAX
0.630
-4.01
1.78
UNIT
Vrms
Full Scale Input Signal Level (for
ADC 0dBFS).
dBV
Vpk-pk
k
Input Resistance
Input Capacitance
DC Offset
Rin
Cin
10
pF
At ADC output with
ADC_HPF_ENA=0
11864
47
LSBs (24-bit)
LSBs (16-bit)
dBFS
Signal to Noise Ratio
SNR
THD
A-weighted
85
91
Total Harmonic Distortion
Total Harmonic Distortion + Noise
Channel Separation
-5.45dBV input
-78
-68
-66
dBFS
THD+N
-5.45dBV input
-76
dBFS
1kHz signal, -5.45dBV
10kHz signal, -5.45dBV
1kHz signal, -5.45dBV
1kHz, 100mVpk-pk
20kHz, 100mV pk-pk
85
dB
dB
dB
80
Channel Level Matching
+/-1
60
Power Supply Rejection Ratio
PSRR
40
Differential stereo line record - IN2L+IN3L / IN2R+IN3R pins to ADC output
Test conditions:
L_MODE = R_MODE = 01b (Differential Line)
LIN_VOL = RIN_VOL = 01111b (+4.2dB)
Total signal path gain = +4.20dB
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
0.586
-4.64
1.657
10
TYP
0.617
-4.20
1.745
12
MAX
0.648
-3.77
1.833
UNIT
Vrms
Differential Line Input full scale
signal level IN2L-IN3L or IN2R-
IN3L (for ADC 0dBFS output)
dBV
Vpk-pk
k
Input Resistance
Input Capacitance
DC Offset
Rin
Cin
10
pF
At ADC output with
ADC_HPF_ENA=0
11864
47
LSBs (24-bit)
LSBs (16-bit)
dBFS
Signal to Noise Ratio
SNR
THD
A-weighted
85
92
Total Harmonic Distortion
Total Harmonic Distortion + Noise
Common Mode Rejection Ratio
Channel Separation
-5.2dBV input
-80
-66
-64
dBFS
THD+N
CMRR
-5.2dBV input
-78
dBFS
1kHz, 100mV pk-pk
1kHz signal, -5.2dBV
10kHz signal, -5.2dBV
1kHz signal, -5.2dBV
1kHz, 100mVpk-pk
20kHz, 100mV pk-pk
60
dB
85
dB
dB
dB
80
Channel Level Matching
+/-1
60
Power Supply Rejection Ratio
PSRR
40
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WM8903
Single-ended stereo record from analogue microphones - IN2L / IN2R pins to ADC output
Test conditions:
L_MODE = R_MODE = 00b (Single ended)
LIN_VOL = RIN_VOL = 11111b (+28.3dB)
Total signal path gain = +34.3dB, incorporating 6dB single-ended to differential conversion gain
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
0.019
-34.3
0.055
12
MAX
UNIT
Vrms
Single-ended mic input full-scale
Signal Level (for ADC 0dBFS
output)
dBV
Vpk-pk
k
Input Resistance
Input Capacitance
DC offset
Rin
Cin
10
10
pF
At ADC output with
ADC_HPF_ENA=0
11864
47
LSBs (24-bit)
LSBs (16-bit)
dBFS
Signal to Noise Ratio
SNR
THD
A-weighted
-35dBV input
73
Total Harmonic Distortion
Total Harmonic Distortion + Noise
Channel Level Matching
-78
dBFS
THD+N
-35dBV input
-77
dBFS
1kHz signal, -35dBV
1kHz, 100mVpk-pk
20kHz, 100mV pk-pk
+/-3
60
dB
Power Supply Rejection Ratio
PSRR
dB
40
Differential stereo record from analogue microphones - IN1L+IN2L / IN1R+IN2R pins to ADC output
Test conditions:
L_MODE = R_MODE = 10b (Differential mic)
LIN_VOL = RIN_VOL = 00111b (+30dB)
Total signal path gain = +30dB
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
0.032
-30
MAX
UNIT
Vrms
dBV
Differential Mic Input Full Scale
Signal Level
IN1L-IN2L / IN1R-IN2R (for ADC
0dBFS output)
0.089
Vpk-pk
Input Resistance
Input Capacitance
DC Offset
Rin
Cin
100
120
10
k
pF
At ADC output with
ADC_HPF_ENA=0
189813
742
75
LSBs (24-bit)
LSBs (16-bit)
dBFS
Signal to Noise Ratio
SNR
THD
A-weighted
Total Harmonic Distortion
Total Harmonic Distortion + Noise
Common Mode Rejection Ratio
Channel Separation
-31dBV input
-78
-72
60
dBFS
THD+N
CMRR
-31dBV input
dBFS
1kHz, 100mVpk-pk
1kHz signal, -31dBV
10kHz signal, -31dBV
1kHz signal, -31dBV
1kHz, 100mVpk-pk
20kHz, 100mV pk-pk
dB
85
dB
80
Channel Level Matching
PSRR (Referred to Input)
+/-1
60
dB
dB
PSRR
40
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Production Data
PGA and microphone boost
PARAMETER
TEST CONDITIONS
L_MODE/R_MODE= 00b or 01b
L_MODE/R_MODE= 10b
MIN
TYP
-1.55
+12
MAX
UNIT
Minimum PGA gain setting
dB
Maximum PGA gain setting
L_MODE/R_MODE= 00b or 01b
L_MODE/R_MODE= 10b
+28.28
+30
dB
Single-ended to differential
conversion gain
L_MODE/R_MODE= 00b
+6
dB
dB
PGA gain accuracy
L_MODE/R_MODE= 00b
Gain -1.55 to +6.7dB
-1
-1.5
-1
+1
+1.5
+1
L_MODE/R_MODE= 00b
Gain +7.5 to +28.3dB
L_MODE/R_MODE= 1X
Gain +12 to +24dB
L_MODE/R_MODE= 1X
Gain +27 to +30dB
-1.5
+1.5
Mute attenuation
all modes of operation
L_MODE/R_MODE= 00b or 01b
88
dB
Equivalent input noise
114
828
µVrms
nV/√Hz
OUTPUT SIGNAL PATH
Stereo Playback to Headphones - DAC input to HPOUTL+HPOUTR pins with 15 load
Test conditions: HPOUTL_VOL = HPOUTR_VOL = 111001b (0dB)
PARAMETER
SYMBOL
TEST CONDITIONS
1% THD
MIN
TYP
28
MAX
UNIT
mW
Output Power (per Channel)
Po
RLoad= 30
0.91
-0.76
30
Vrms
dBV
mW
1% THD
RLoad= 15
0.67
-3.47
Vrms
dBV
DC Offset
DC servo enabled, calibration
complete.
0
+/-1.5
mV
dB
Signal to Noise Ratio
SNR
THD
A-weighted
90
96
-93
-82
-83
-83
-90
-82
-81
-81
100
85
Total Harmonic Distortion
RL=30; Po=2mW
RL=30; Po=20mW
RL=15; Po=2mW
RL=15; Po=20mW
RL=30; Po=2mW
RL=30; Po=20mW
RL=15; Po=2mW
RL=15; Po=20mW
1kHz signal, 0dBFS
10kHz signal, 0dBFS
1kHz signal, 0dBFS
1kHz, 100mV pk-pk
20kHz, 100mV pk-pk
dB
dB
-72
-70
Total Harmonic Distortion + Noise
Channel Separation
THD+N
dB
dB
dB
Channel Level Matching
+/-1
60
Power Supply Rejection Ratio
PSRR
40
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WM8903
Stereo Playback to Line-out - DAC input to LINEOUTL+LINEOUTR pins with 3.01k / 50pF load
Test conditions: LINEOUTL_VOL = LINEOUTR_VOL = 111001b (0dB)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
0.95
-0.446
2.69
0
TYP
1.0
0
MAX
1.05
UNIT
Vrms
dBV
Full Scale Output Signal Level
DAC 0dBFS output at 0dB
volume
0.424
2.97
2.83
Vpk-pk
mV
DC offset
DC servo enabled.
Calibration complete.
A-weighted
+/-1.5
Signal to Noise Ratio
SNR
THD
90
95
-86
dB
dB
dB
Total Harmonic Distortion
Total Harmonic Distortion + Noise
Channel Separation
3.01k load
-77
-75
THD+N
3.01k load
-84
1kHz signal, 0dBFS
10kHz signal, 0dBFS
1kHz signal, 0dBFS
1kHz, 100mVpk-pk
20kHz, 100mV pk-pk
100
85
dB
dB
dB
Channel Level Matching
+/-1dB
60
Power Supply Rejection Ratio
PSRR
40
Stereo Playback to Differential Line-out - DAC input to LOP+LON or ROP+RON pins with 10k / 50pF load
Test conditions: SPKR_LVOL = SPKR_RVOL = 111001b (0dB)
PARAMETER
SYMBOL
TEST CONDITIONS
0dBFS
MIN
0.95
TYP
1.0
MAX
1.05
Full Scale Output Signal Level
Vrms
dBV
Measured Differentially
-0.446
2.69
0
0.424
2.97
2.83
AVDD/2
+/-7
95
Vpk-pk
Common mode output level
Common mode output error
Signal to Noise Ratio
mV
dB
dB
dB
SNR
THD
A-weighted
90
Total Harmonic Distortion
Total Harmonic Distortion + Noise
Channel Separation
-92
-82
-80
THD+N
-88
1kHz signal, 0dBFS
10kHz signal, 0dBFS
1kHz signal
100
85
dB
dB
dB
Channel Level Matching
+/-1dB
60
Power Supply Rejection Ratio
PSRR
1kHz, 100mVpk-pk
20kHz, 100mV pk-pk
40
Output PGAs (HP, LINE and Differential LINE)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
dB
Minimum PGA gain setting
Maximum PGA gain setting
PGA Gain Step Size
PGA gain accuracy
PGA gain accuracy
Mute attenuation
-57
6
dB
1
dB
+6dB to 0dB
0dB to -57dB
-1.5
-1
+1.5
+1
dB
dB
HPOUTL/R
77
79
dB
LINEOUTL/R
Differential LINE
(LOP-LOR/ROP-RON)
105
dB
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BYPASS PATH
Differential stereo line input to stereo line output- IN2L-IN3L / IN2R-IN3R pins to LINEOUTL+LINEOUTR pins with 3.01k /
50pF load
Test conditions:
L_MODE = R_MODE = 01b (Differential Line)
LIN_VOL = RIN_VOL = 00101b (0dB)
LINEOUTL_VOL = LINEOUTR_VOL = 111001b (0dB)
Total signal path gain = 0dB
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
1.0
0
MAX
UNIT
Vrms
dBV
Maximum Line Input Signal Level
applied to IN2L or IN2R
2.83
1.0
0
Vpk-pk
Vrms
dBV
Full Scale Output Signal Level
0.95
-0.446
2.69
85
1.05
0.424
2.97
2.83
97
Vpk-pk
dBV
Signal to Noise Ratio
SNR
THD
A-weighted
Total Harmonic Distortion
Total Harmonic Distortion + Noise
Channel Separation
-1.0dBV input
-92
-89
85
-82
-80
dBV
THD+N
-1.0dBV input
dBV
1kHz signal, -1dBV
10kHz signal, -1dBV
1kHz signal, -1dBV
1kHz, 100mVpk-pk
20kHz, 100mV pk-pk
dB
dB
dB
80
Channel Level Matching
+/-1
56
Power Supply Rejection Ratio
PSRR
40
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CHARGE PUMP
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Charge pump start-up time
External component requirements
40
µs
To achieve specified headphone output power and performance
Flyback capacitor
(between CFB1 and CFB2 pins)
CFB
at 2V
1
µF
VPOS capacitor
VNEG capacitor
at 2V
at 2V
2
2
µF
µF
FLL
PARAMETER
Input Frequency
SYMBOL
TEST CONDITIONS
FLL_CLK_REF_DIV = 00
FLL_CLK_REF_DIV = 01
MIN
TYP
MAX
13.5
27
UNIT
MHz
MHz
ms
FREF
0.032
0.032
Lock time
2
Free-running mode start-up time
Free-running mode frequency accuracy
VMID enabled
100
s
Reference supplied initially
No reference provided
+/-10
+/-30
%
%
OTHER PARAMETERS
VMID Reference
PARAMETER
TEST CONDITIONS
MIN
TYP
AVDD/2
MAX
+3%
UNIT
Midrail Reference Voltage (VMID pin)
–3%
V
Microphone bias (for analogue electret condenser microphones)
Additional test conditions: MICBIAS_ENA=1, all parameters measured at the MICBIAS pin
PARAMETER
SYMBOL
VMICBIAS
IMICBIAS
TEST CONDITIONS
MIN
TYP
MAX
UNIT
V
Bias Voltage
3mA load current
-5%
0.9×AVDD
+5%
Maximum source current
Noise spectral density
Power Supply Rejection Ratio
4
mA
At 1kHz
19
50
70
nV/√Hz
PSRR
1kHz, 100mV pk-pk
20kHz, 100mV pk-pk
dB
MICBIAS Current Detect Function (See Notes 1, 2)
Current Detect Threshold
(Microphone insertion)
Current Detect Threshold
(Microphone removal)
MICDET_THR = 00
100
A
15
Delay Time for Current Detect
Interrupt
tDET
1.25-15
ms
MICBIAS Short Circuit (Hook Switch) Detect Function (See Notes 1, 2)
Short Circuit Detect Threshold
(Button press)
MICSHORT_THR = 00
400
520
50
647
A
Short Circuit Detect Hysteresis
(See Note 3)
Minimum Delay Time for
Short Circuit Detect Interrupt
tSHORT
40
ms
Hz
Short Circuit Detect
250
measurement frequency
Notes:
1. If AVDD 1.8, current threshold values should be multiplied by (AVDD/1.8)
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2. MICBIAS current detect and short circuit (Hook switch) detect functionality tested using GPIO pin rather than by
interrupt.
3. Hysteresis = difference between Button Press and Button Release thresholds
Digital Inputs / Outputs
PARAMETER
SYMBOL
VIH
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Input HIGH Level
Input LOW Level
Output HIGH Level
Output LOW Level
0.7DBVDD
V
V
V
V
VIL
0.3DBVDD
0.1DBVDD
VOH
IOH = +1mA
IOL = -1mA
0.9DBVDD
VOL
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WM8903
POWER CONSUMPTION
The WM8903 power consumption is dependent on many parameters. Most significantly, it depends
on supply voltages, sample rates, mode of operation, and output loading.
The power consumption on each supply rail varies approximately with the square of the voltage.
Power consumption is greater at fast sample rates than at slower ones. When the digital audio
interface is operating in Master mode, the DBVDD current is significantly greater than in Slave mode.
(Note also that power savings can be made by using MCLK as the BCLK source in Slave mode.) The
output load conditions (impedance, capacitance and inductance) can also impact significantly on the
device power consumption.
COMMON TEST CONDITIONS
Unless otherwise stated, the following test conditions apply throughout the following sections:
Ambient temperature = +25°C
Audio signal = quiescent (zero amplitude)
Sample rate = 44.1kHz
MCLK = 12MHz
Audio interface mode = Master (LRCLK_DIR=1, BCLK_DIR=1)
CLK_SRC_SEL = 0 (System clock comes direct from MCLK, not from FLL)
Additional, variant test conditions are quoted within the relevant sections below. Where applicable,
power dissipated in the headphone or line loads is included.
POWER CONSUMPTION MEASUREMENTS
Single-ended stereo line record - IN1L/R, IN2L/R or IN3L/R pins to ADC output.
Test conditions:
L_MODE = R_MODE = 00b (Single ended)
LIN_VOL = RIN_VOL = 00000b (-1.55dB)
ADC_OSR128 = 0
Variant test conditions
AVDD
mA
DCVDD
DBVDD
CPVDD
TOTAL
mW
7.9
V
V
mA
1.04
0.50
V
mA
0.10
0.03
V
mA
0.00
0.00
44.1kHz sample rate
8kHz sample rate
1.8
1.8
3.60
3.40
1.2
1.2
1.8
1.8
1.8
1.8
6.8
Differential stereo record from analogue microphones - IN1L/R, IN2L/R or IN3L/R pins to ADC out.
Test conditions:
L_MODE = R_MODE = 10b (Differential mic)
ADC_OSR128 = 0
Variant test conditions
AVDD
mA
DCVDD
DBVDD
CPVDD
TOTAL
mW
7.9
V
V
mA
1.00
0.50
V
mA
0.10
0.03
V
mA
0.00
0.00
44.1kHz sample rate
8kHz sample rate
1.8
1.8
3.60
3.40
1.2
1.2
1.8
1.8
1.8
1.8
6.8
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Stereo Playback to Headphones - DAC input to HPOUTL+HPOUTR pins with 30Ω load.
Test conditions
DACBIAS_SEL = 01b (Normal bias x 0.5)
DACVMID_BIAS_SEL = 11b (Normal bias x 0.75)
PGA_BIAS = 011b (Normal bias x 0.5)
CP_DYN_PWR = 1b (Charge pump controlled by real-time audio level)
Variant test conditions
AVDD
mA
DCVDD
DBVDD
CPVDD
mA
TOTAL
V
V
mA
0.76
0.76
0.90
0.92
0.65
0.71
V
mA
0.00
0.09
0.09
0.09
0.03
0.03
V
mW
4.5
Slave mode, 44.1kHz sample rate, quiescent
Master mode, 44.1kHz sample rate, quiescent
Master mode, 44.1kHz, Po = 0.1mW/channel
Master mode, 44.1kHz, Po = 1mW/channel
Master mode, 8kHz sample rate, quiescent
Master mode, 8kHz, Po = 0.1mW/channel
1.8
1.8
1.8
1.8
1.8
1.8
1.60
1.60
1.60
1.60
1.60
1.60
1.2
1.2
1.2
1.2
1.2
1.2
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
0.41
0.41
1.85
5.77
0.41
1.85
4.7
7.5
14.5
4.4
7.1
Stereo Playback to Line-out - DAC input to LINEOUTL+LINEOUTR or HPOUTL+HPOUTR pins with 3.01kΩ / 50pF load
Test conditions:
CP_DYN_PWR = 1b (Charge pump controlled by real-time audio level)
Variant test conditions
AVDD
mA
DCVDD
DBVDD
CPVDD
TOTAL
mW
5.2
V
V
mA
0.76
0.68
V
mA
0.09
0.03
V
mA
0.32
0.32
44.1kHz sample rate
8kHz sample rate
1.8
1.8
1.95
1.95
1.2
1.2
1.8
1.8
1.8
1.8
4.9
Stereo analogue bypass to headphones - IN1L/R, IN2L/R or IN3L/R pins to HPOUTL+HPOUTR pins with 30Ω load.
Test conditions: Audio interface disabled
Note that the Analogue bypass configuration does not benefit from the Class W dynamic control, and the power consumption is
greater in this case than the DAC to Line-Out case. See “Charge Pump” section.
Variant test conditions
AVDD
mA
DCVDD
DBVDD
CPVDD
TOTAL
mW
V
V
mA
0.12
0.12
V
mA
0.00
0.00
V
mA
1.54
4.54
Quiescent
1.8
1.8
1.46
1.46
1.2
1.2
1.8
1.8
1.8
1.8
5.5
Po = 0.1mW/channel
11.0
Off
Test conditions: No Clocks applied
Variant test conditions
AVDD
DCVDD
DBVDD
CPVDD
TOTAL
mW
V
mA
V
mA
V
mA
V
mA
None
1.8
0.01
1.2
0.012
1.8
0.003
1.8
0.005
0.047
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SIGNAL TIMING REQUIREMENTS
COMMON TEST CONDITIONS
Unless otherwise stated, the following test conditions apply throughout the following sections:
Ambient temperature = +25°C
DCVDD = 1.2V
DBVDD = AVDD = CPVDD = 1.8V
DGND = AGND = CPGND = 0V
Additional, specific test conditions are given within the relevant sections below.
MASTER CLOCK
Figure 1 Master Clock Timing
Master Clock Timing
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
40
TYP
MAX
UNIT
ns
MCLKDIV2=1
MCLKDIV2=0
DCVDD 1.62V
MCLKDIV2=0
MCLK cycle time
TMCLKY
80
ns
54.25
ns
TMCLKY
MCLK cycle time
MCLK duty cycle
TMCLKDS
60:40
40:60
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AUDIO INTERFACE TIMING
MASTER MODE
Figure 2 Audio Interface Timing – Master Mode
Audio Interface Timing – Master Mode
PARAMETER
SYMBOL
tDL
MIN
TYP
MAX
10
UNIT
ns
LRC propagation delay from BCLK falling edge
ADCDAT propagation delay from BCLK falling edge
DACDAT setup time to BCLK rising edge
DACDAT hold time from BCLK rising edge
tDDA
10
ns
tDST
10
10
ns
tDHT
ns
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SLAVE MODE
Figure 3 Audio Interface Timing – Slave Mode
Audio Interface Timing – Slave Mode
PARAMETER
SYMBOL
tBCY
MIN
50
20
20
10
10
10
TYP
MAX
UNIT
ns
BCLK cycle time
BCLK pulse width high
tBCH
ns
BCLK pulse width low
tBCL
ns
LRC set-up time to BCLK rising edge
LRC hold time from BCLK rising edge
DACDAT hold time from BCLK rising edge
ADCDAT propagation delay from BCLK falling edge
DACDAT set-up time to BCLK rising edge
tLRSU
tLRH
ns
ns
tDH
ns
tDD
30
ns
tDS
20
ns
Note: BCLK period must always be greater than or equal to MCLK period.
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TDM MODE
In TDM mode, it is important that two devices to not attempt to drive the ADCDAT pin simultaneously.
The timing of the WM8903 ADCDAT pin tri-stating at the start and end of the data transmission is
described below.
Figure 4 Audio Interface Timing – TDM Mode
Audio Interface Timing – TDM Mode
PARAMETER
SYMBOL
MIN
TYP
4
MAX
UNIT
ns
ADCDAT setup time from BCLK falling edge
ADCDAT release time from BCLK falling edge
25
ns
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CONTROL INTERFACE TIMING
Figure 5 Control Interface Timing
Control Interface Timing
PARAMETER
SYMBOL
MIN
TYP
MAX
UNIT
kHz
µs
SCLK Frequency
526
SCLK Low Pulse-Width
SCLK High Pulse-Width
Hold Time (Start Condition)
Setup Time (Start Condition)
Data Setup Time
t1
t2
t3
t4
t5
t6
t7
t8
t9
tps
1.3
600
600
600
100
ns
ns
ns
ns
SDIN, SCLK Rise Time
SDIN, SCLK Fall Time
Setup Time (Stop Condition)
Data Hold Time
300
300
ns
ns
600
0
ns
900
5
ns
Pulse width of spikes that will be suppressed
ns
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DIGITAL FILTER CHARACTERISTICS
PARAMETER
ADC Filter
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Passband
+/- 0.05dB
-6dB
0
0.454 fs
+/- 0.05
0.5fs
Passband Ripple
Stopband
dB
dB
0.546s
-60
Stopband Attenuation
DAC Normal Filter
Passband
f > 0.546 fs
+/- 0.05dB
-6dB
0
0.454 fs
+/- 0.03
0.5 fs
Passband Ripple
Stopband
0.454 fs
dB
dB
0.546 fs
-50
Stopband Attenuation
DAC Sloping Stopband Filter
Passband
F > 0.546 fs
+/- 0.03dB
+/- 1dB
-6dB
0
0.25 fs
0.25 fs
0.454 fs
0.5 fs
Passband Ripple
Stopband 1
0.25 fs
+/- 0.03
0.7 fs
dB
dB
dB
dB
0.546 fs
-60
Stopband 1 Attenuation
Stopband 2
f > 0.546 fs
f > 0.7 fs
0.7 fs
-85
1.4 fs
Stopband 2 Attenuation
Stopband 3
1.4 fs
-55
Stopband 3 Attenuation
F > 1.4 fs
DAC FILTERS
ADC FILTERS
Mode
Group Delay
16.5 / fs
Mode
Normal
Group Delay
16.5 / fs
Normal
Sloping Stopband
18 / fs
TERMINOLOGY
1. Stop Band Attenuation (dB) – the degree to which the frequency spectrum is attenuated (outside audio band)
2. Pass-band Ripple – any variation of the frequency response in the pass-band region
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DAC FILTER RESPONSES
Figure 6 DAC Filter Response for
Figure 7 DAC Filter Response for
CLK_SYS_MODE = 00b or 01b
DAC_SB_FILT = 1b (Sloping StopBand Filter)
Sample Rate 24kHz
CLK_SYS_MODE = 10b (Clock is 250 x fs related)
DAC_SB_FILT = 1b (Sloping StopBand Filter)
Sample Rate 24kHz
Figure 8 DAC Filter Response for
Figure 9 DAC Filter Response for
CLK_SYS_MODE = 00b or 01b
DAC_SB_FILT = 0b (Normal Filter)
Sample Rate > 24kHz
CLK_SYS_MODE = 10b (Clock is 250 x fs related)
DAC_SB_FILT = 0b (Normal Filter)
Sample Rate > 24kHz (except 88.2kHz)
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Figure 10 DAC Filter Response for
CLK_SYS_MODE = 01b (Clock is 272 x fs related)
DAC_SB_FILT = 0b (Normal Filter)
Sample Rate = 88.2kHz
ADC FILTER RESPONSES
Figure 11 ADC Filter Response for
Figure 12 ADC Filter Response for
CLK_SYS_MODE = 00b or 01b
CLK_SYS_MODE = 10b (not applicable to 88.2/96kHz)
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WM8903
Figure 13 ADC Filter Passband Ripple for
CLK_SYS_MODE = 10b
ADC HIGH PASS FILTER RESPONSES
2.1246m
-1.1717
-2.3455
-3.5193
-4.6931
-5.8669
-7.0407
-8.2145
-9.3883
-10.562
-11.736
-2.3338m
-8.3373
-16.672
-25.007
-33.342
-41.677
-50.012
-58.347
-66.682
-75.017
-83.352
1
2.6923
7.2484
19.515
52.54
141.45
380.83
1.0253k
2.7605k
7.432k
20.009k
2
5.0248
12.624
31.716
79.683
200.19
502.96
1.2636k
3.1747k
7.9761k
20.039k
MAGNITUDE(dB)
hpf_response.res MAGNITUDE(dB)
hpf_response2.res MAGNITUDE(dB)
hpf_response2.res#1 MAGNITUDE(dB)
Figure 14 ADC Digital High Pass Filter Frequency
Response (48kHz, Hi-Fi Mode, ADC_HPF_CUT[1:0]=00)
Figure 15 ADC Digital High Pass Filter Ripple (48kHz,
Voice Mode, ADC_HPF_CUT=01, 10 and 11)
The plots shown are for 48kHz. For other sample rates, the plots should be scaled accordingly.
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DE-EMPHASIS FILTER RESPONSES
MAGNITUDE(dB)
MAGNITUDE(dB)
0.3
0.25
0.2
0
0
5000
10000
15000
20000
-1
-2
-3
0.15
0.1
-4
-5
0.05
0
-6
-7
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
-0.05
-0.1
-0.15
-8
-9
-10
Frequency (Hz)
Frequency (Hz)
Figure 16 De-Emphasis Digital Filter Response (32kHz)
Figure 17 De-Emphasis Error (32kHz)
MAGNITUDE(dB)
MAGNITUDE(dB)
0
0.2
0
5000
10000
15000
20000
25000
-1
-2
0.15
0.1
0.05
0
-3
-4
-5
-6
-7
0
5000
10000
15000
20000
25000
-8
-0.05
-0.1
-9
-10
Frequency (Hz)
Frequency (Hz)
Figure 18 De-Emphasis Digital Filter Response (44.1kHz)
Figure 19 De-Emphasis Error (44.1kHz)
MAGNITUDE(dB)
MAGNITUDE(dB)
0.15
0
0
5000
10000
15000
20000
25000
30000
0.1
0.05
0
-2
-4
-6
0
5000
10000
15000
20000
25000
30000
-0.05
-0.1
-8
-10
-12
-0.15
Frequency (Hz)
Frequency (Hz)
Figure 20 De-Emphasis Digital Filter Response (48kHz)
Figure 21 De-Emphasis Error (48kHz)
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DEVICE DESCRIPTION
INTRODUCTION
The WM8903 is a high performance ultra-low power stereo CODEC optimised for portable audio
applications. Flexible analogue interfaces and powerful digital signal processing (DSP) make it ideal
for small portable devices.
The WM8903 supports up to 6 analogue audio inputs. One pair of single-ended or differential
microphone/line inputs is selected as the ADC input source. An integrated bias reference is provided
to power standard electret microphones.
A two-channel digital microphone interface is also supported, with direct input to the DSP core
bypassing the ADCs.
Two pairs of ground-referenced Class W headphone / line outputs are provided; these are powered
from an integrated Charge Pump, enabling high quality, power efficient headphone playback without
any requirement for DC blocking capacitors. A DC Servo circuit is available for DC offset correction,
thereby suppressing pops and reducing power consumption. Two differential line outputs are also
provided; these are also capable of driving external speaker drivers. Ground loop feedback is
available on the ground-referenced headphone and line outputs, providing rejection of noise on the
ground connections. All outputs use Wolfson SilentSwitch™ technology for pop and click
suppression.
The stereo ADCs and DACs are of hi-fi quality, using a 24-bit low-order oversampling architecture to
deliver optimum performance. A high pass filter is available in the ADC path for removing DC offsets
and suppressing low frequency noise such as mechanical vibration and wind noise. A digital mixing
path from the ADC to the DAC provides a sidetone of enhanced quality during voice calls. DAC soft
mute and un-mute is available for pop-free music playback.
The integrated Dynamic Range Controller (DRC) provides further processing capability of the digital
audio paths. The DRC provides compression and signal level control to improve the handling of
unpredictable signal levels. ‘Anti-clip’ and ‘quick release’ algorithms improve intelligibility in the
presence of transients and impulsive noises.
The WM8903 has a highly flexible digital audio interface, supporting a number of protocols, including
I2S, DSP, MSB-first left/right justified, and can operate in master or slave modes. PCM operation is
supported in the DSP mode. A-law and -law companding are also supported. Time division
multiplexing (TDM) is available to allow multiple devices to stream data simultaneously on the same
bus, saving space and power.
The system clock CLK_SYS provides clocking for the ADCs, DACs, DSP core, digital audio interface
and other circuits. CLK_SYS can be derived directly from the MCLK pin or via an integrated FLL,
providing flexibility to support a wide range of clocking schemes. Typical portable system MCLK
frequencies, and sample rates from 8kHz to 96kHz are all supported. The clocking circuits are
configured automatically from the sample rate (fs) and from the CLK_SYS / fs ratio.
The integrated FLL can be used to generate CLK_SYS from a wide variety of different reference
sources and frequencies. The FLL can accept a wide range of reference frequencies, which may be
high frequency (e.g. 13MHz) or low frequency (eg. 32.768kHz). The FLL is tolerant of jitter and may
be used to generate a stable CLK_SYS from a less stable input signal. The integrated FLL can be
used as a free-running oscillator, enabling autonomous clocking of the Charge Pump and DC Servo if
required.
The WM8903 uses a standard 2-wire control interface, providing full software control of all features,
together with device register readback. An integrated Control Write Sequencer enables automatic
scheduling of control sequences; commonly-used signal configurations may be selected using ready-
programmed sequences, including time-optimised control of the WM8903 pop suppression features.
It is an ideal partner for a wide range of industry standard microprocessors, controllers and DSPs.
Unused circuitry can be disabled under software control, in order to save power; low leakage currents
enable extended standby/off time in portable battery-powered applications.
Up to
5 GPIO pins may be configured for miscellaneous input/output functions such as
button/accessory detect inputs, or for clock, system status, or programmable logic level output for
control of additional external circuitry. Interrupt logic, status readback and de-bouncing options are
supported within this functionality.
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ANALOGUE INPUT SIGNAL PATH
The WM8903 has six analogue input pins, which may be used to support connections to multiple
microphone or line input sources. The input multiplexer on the Left and Right channels can be used to
select different configurations for each of the input sources. The analogue input paths can support
line and microphone inputs, in single-ended and differential modes. The input stage can also provide
common mode noise rejection in some configurations.
The Left and Right analogue input channels are routed to the Analogue to Digital converters (ADCs).
There is also a bypass path for each channel, enabling the signal to be routed directly to the output
mixers.
The WM8903 input signal paths and control registers are illustrated in Figure 22.
Single-Ended (inverting) Mode: Gain -1.55dB to +28.5dB, non-linear steps
Differential Line Mode: Gain -1.55dB to +28.5dB, non-linear steps
Differential Microphone Mode: Gain +12dB to +30dB, 3dB steps
BYPASSL
IN1L
IN2L
-
+
MUX
ADC L
IN3L
INL_ENA
INL_CM_ENA
LIN_MUTE
LIN_VOL
L_MODE
VMID
L_IP_SEL_N
L_IP_SEL_P
Single-Ended (inverting) Mode: Gain -1.55dB to +28.5dB, non-linear steps
Differential Line Mode: Gain -1.55dB to +28.5dB, non-linear steps
Differential Microphone Mode: Gain +12dB to +30dB, 3dB steps
BYPASSR
IN1R
IN2R
IN3R
-
+
MUX
ADC R
INR_ENA
INR_CM_ENA
RIN_MUTE
RIN_VOL
R_MODE
VMID
R_IP_SEL_N
R_IP_SEL_P
Figure 22 Block Diagram for Input Signal Path
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INPUT PGA ENABLE
The input PGAs (Programmable Gain Amplifiers) and Multiplexers are enabled using register bits
INL_ENA and INR_ENA, as shown in Table 1.
REGISTER
ADDRESS
BIT
LABEL
INL_ENA
DEFAULT
DESCRIPTION
R12 (0Ch)
Left Input PGA Enable
0 = disabled
1
0
Power
Management
0
1 = enabled
INR_ENA
Right Input PGA Enable
0 = disabled
0
0
1 = enabled
Table 1 Input PGA Enable
To enable the input PGAs, the reference voltage VMID and the bias current must also be enabled.
See “Reference Voltages and Master Bias” for details of the associated controls VMID_RES and
BIAS_ENA.
INPUT PGA CONFIGURATION
The analogue input channels can each be configured in three different modes, which are as follows:
.
.
.
Single-Ended Mode (Inverting)
Differential Line Mode
Differential Mic Mode
The mode is selected by the L_MODE and R_MODE fields for the Left and Right channels
respectively. The input pins are selected using the L_IP_SEL_N and L_IP_SEL_P fields for the Left
channel and the R_IP_SEL_N and R_IP_SEL_P for the Right channel. In Single-Ended mode,
L_IP_SEL_N alone determines the Left Input pin, and the R_IP_SEL_N determines the Right Input
pin.
The three modes are illustrated in Figure 23, Figure 24 and Figure 25. It should be noted that the
available gain and input impedance varies between configurations (see also “Electrical
Characteristics”). The input impedance is constant with PGA gain setting.
The Input PGA modes are selected and configured using the register fields described in Table 2.
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
R46 (2Eh)
5:4
L_IP_SEL_N
[1:0]
00
In Single-Ended or Differential Line
Modes, this field selects the input pin
for the inverting side of the left input
path.
Analogue Left
Input 1
In Differential Mic Mode, this field
selects the input pin for the non-
inverting side of the left input path.
00 = IN1L
01 = IN2L
1X = IN3L
3:2
L_IP_SEL_P
[1:0]
01
In Single-Ended or Differential Line
Modes, this field selects the input pin
for the non-inverting side of the left
input path.
In Differential Mic Mode, this field
selects the input pin for the inverting
side of the left input path.
00 = IN1L
01 = IN2L
1X = IN3L
1:0
5:4
L_MODE [1:0]
00
00
Sets the mode for the left analogue
input:
00 = Single-Ended
01 = Differential Line
10 = Differential MIC
11 = Reserved
R47 (2Fh)
R_IP_SEL_N
[1:0]
In Single-Ended or Differential Line
Modes, this field selects the input pin
for the inverting side of the right input
path.
Analogue
Right Input 1
In Differential Mic Mode, this field
selects the input pin for the non-
inverting side of the right input path.
00 = IN1R
01 = IN2R
1X = IN3R
3:2
R_IP_SEL_P
[1:0]
01
In Single-Ended or Differential Line
Modes, this field selects the input pin
for the non-inverting side of the right
input path.
In Differential Mic Mode, this field
selects the input pin for the inverting
side of the right input path.
00 = IN1R
01 = IN2R
1X = IN3R
1:0
R_MODE [1:0]
00
Sets the mode for the right analogue
input:
00 = Single-Ended
01 = Differential Line
10 = Differential MIC
11 = Reserved
Table 2 Input PGA Mode Selection
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SINGLE-ENDED INPUT
The Single-Ended PGA configuration is illustrated in Figure 23 for the Left channel. The available
gain in this mode is from -1.55dB to +28.5dB in non-linear steps. The input impedance is 12k. The
input to the ADC is phase inverted with respect to the selected input pin. Different input pins can be
selected in the same mode by altering the L_IP_SEL_N field.
The equivalent configuration is also available on the Right channel; this can be selected
independently of the Left channel mode.
BYPASSL
-1.55dB to +28.5dB,
non-linear steps
IN1L
M
U
X
IN2L
IN3L
-
+
ADC L
VMID
INL_ENA
LIN_MUTE
LIN_VOL
L_IP_SEL_N
Single-Ended (inverting) Mode (L_MODE = 00)
Figure 23 Single Ended Mode
DIFFERENTIAL LINE INPUT
The Differential Line PGA configuration is illustrated in Figure 24 for the Left channel. The available
gain in this mode is from -1.55dB to +28.5dB in non-linear steps. The input impedance is 12k. The
input to the ADC is in phase with the input pin selected by L_IP_SEL_P. The input to the ADC is
phase inverted with respect to the input pin selected by L_IP_SEL_N.
As an option, common mode noise rejection can be provided in this PGA configuration, as illustrated
in Figure 24. This is enabled using the register bits defined in Table 5.
The equivalent configuration is also available on the Right channel; this can be selected
independently of the Left channel mode.
BYPASSL
-1.55dB to +28.5dB,
non-linear steps
IN1L
M
U
X
IN2L
IN3L
-
+
+
ADC L
-
INL_ENA
LIN_MUTE
LIN_VOL
L_IP_SEL_N
M
U
X
INL_CM_ENA
L_IP_SEL_P
Differential Line Mode (L_MODE = 01)
Figure 24 Differential Line Mode
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DIFFERENTIAL MICROPHONE INPUT
The Differential Mic PGA configuration is illustrated in Figure 25 for the Left channel. The available
gain in this mode is from +12dB to +30dB in 3dB linear steps. The input impedance is 120k. The
input to the ADC is in phase with the input pin selected by L_IP_SEL_N. The input to the ADC is
phase inverted with respect to the input pin selected by L_IP_SEL_P.
Note that the inverting input pin is selected using L_IP_SEL_P and the non-inverting input pin is
selected using L_IP_SEL_N. This is not the same as for the Differential Line mode.
The equivalent configuration is also available on the Right channel; this can be selected
independently of the Left channel mode.
Figure 25 Differential Microphone Mode
INPUT PGA GAIN CONTROL
The volume control gain for the Left and Right channels be independently controlled using the
LIN_VOL and RIN_VOL register fields as described in Table 3. The available gain range varies
according to the selected PGA Mode as detailed in Table 4. Note that the value ‘00000’ must not be
used in Differential Mic Mode, as the PGA will not function correctly under this setting. In single-
ended mode (L_MODE / R_MODE = 00b), the conversion from single-ended to differential within the
WM8903 adds a further 6dB of gain to the signal path.
Each input channel can be independently muted using LINMUTE and RINMUTE.
It is recommended to not adjust the gain dynamically whilst the signal path is enabled; the signal
should be muted at the input or output stage prior to adjusting the volume control.
REGISTER
ADDRESS
BIT
LABEL
LINMUTE
DEFAULT
DESCRIPTION
R44 (2Ch)
7
1
Left Input PGA Mute
Analogue Left
Input 0
0 = not muted
1 = muted
4:0
7
LIN_VOL [4:0]
RINMUTE
00101
1
Left Input PGA Volume
(See Table 4 for volume range)
Right Input PGA Mute
0 = not muted
R45 (2Dh)
Analogue
Right Input 0
1 = muted
4:0
RIN_VOL [4:0]
00101
Right Input PGA Volume
(See Table 4 for volume range)
Table 3 Input PGA Volume Control
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LIN_VOL [4:0],
RIN_VOL [4:0]
GAIN –
GAIN –
SINGLE-ENDED MODE /
DIFFERENTIAL LINE MODE
-1.55 dB
DIFFERENTIAL MIC MODE
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
Not valid
+12 dB
+15 dB
+18 dB
+21 dB
+24 dB
+27 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
+30 dB
-1.3 dB
-1.0 dB
-0.7 dB
-0.3 dB
0.0 dB
+0.3 dB
+0.7 dB
+1.0 dB
+1.4 dB
+1.8 dB
+2.3 dB
+2.7 dB
+3.2 dB
+3.7 dB
+4.2 dB
+4.8 dB
+5.4 dB
+6.0 dB
+6.7 dB
+7.5 dB
+8.3 dB
+9.2 dB
+10.2 dB
+11.4 dB
+12.7 dB
+14.3 dB
+16.2 dB
+19.2 dB
+22.3 dB
+25.2 dB
+28.3 dB
Table 4 Input PGA Volume Range
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INPUT PGA COMMON MODE AMPLIFIER
In Differential Line Mode only, a Common Mode amplifier can be enabled as part of the input PGA
circuit. This feature provides approximately 20dB reduction in common mode noise on the differential
input, which can reduce problematic interference. Since the ADC has differential signal inputs, it has
an inherent immunity to common mode noise (see “Electrical Characteristics”) However, the presence
of Common Mode noise can limit the usable signal range of the ADC path; enabling the Common
Mode amplifier can solve this issue.
It should be noted that the Common Mode amplifier consumes additional power and can also add its
own noise to the input signal. For these reasons, it is recommended that the Common Mode Amplifier
is only enabled if there is a known source of Common Mode interference.
The Common Mode amplifier is controlled by the INL_CM_ENA and INR_CM_ENA fields as
described in Table 5. Although the Common Mode amplifier may be enabled regardless of the input
PGA mode, its function is only effective in the Differential Line Mode configuration.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R46 (2Eh)
INL_CM_ENA
Left Input PGA Common Mode
Rejection enable
6
1
Analogue Left
Input 1
0 = Disabled
1 = Enabled
(only available for L_MODE=01 –
Differential Line)
R47 (2Fh)
INR_CM_ENA
Right Input PGA Common Mode
Rejection enable
6
1
Analogue
Right Input 1
0 = Disabled
1 = Enabled
(only available for R_MODE=01 –
Differential Line)
Table 5 Common Mode Amplifier Enable
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WM8903
ELECTRET CONDENSER MICROPHONE INTERFACE
Electret Condenser microphones may be connected as single-ended or differential inputs to the Input
PGAs described in the “Analogue Input Signal Path” section. The WM8903 provides a low-noise
reference voltage suitable for biasing electret condenser microphones.
The MICBIAS reference is provided on the MICBIAS pin. This reference voltage is enabled by setting
the MICBIAS_ENA register bit, as defined in Table 6.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R6 (06h)
MICBIAS_ENA
MICBIAS Enable
0
0
0 = disabled
1 = enabled
Mic Bias
Control 0
Table 6 MICBIAS Control
MICBIAS CURRENT DETECT
A MICBIAS Current Detect function is provided for external accessory detection. This is provided in
order to detect the insertion/removal of a microphone or the pressing/releasing of the microphone
‘hook’ switch; these events will cause a significant change in MICBIAS current flow, which can be
detected and used to generate a signal to the host processor.
The MICBIAS current detect function is enabled by setting the MICDET_ENA register bit. When this
function is enabled, two current thresholds can be defined, using the MICDET_THR and
MICSHORT_THR registers. When a change in MICBIAS current which crosses either threshold is
detected, then an interrupt event can be generated. In a typical application, accessory insertion would
be detected when the MICBIAS current exceeds MICDET_THR, and microphone hookswitch
operation would be detected when the MICBIAS current exceeds MICSHORT_THR.
The current detect threshold functions are both inputs to the Interrupt control circuit and can be used
to trigger an Interrupt event when either threshold is crossed. Both events can also be indicated as an
output on a GPIO pin - see “General Purpose Input/Output (GPIO)”.
The current detect thresholds are enabled and controlled using the registers described in Table 7.
Performance parameters for this circuit block can be found in the “Electrical Characteristics” section.
Hysteresis and filtering is also provided in the both current detect circuits to improve reliability in
conditions where AC current spikes are present due to ambient noise conditions. These features are
described in the following section. Further guidance on the usage of the MICBIAS current monitoring
features is also described in the following pages.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R6 (06h)
MICDET_THR
[1:0]
MICBIAS Current Detect Insertion
Threshold
5:4
00
Mic Bias
Control 0
00 = 0.063mA
01 = 0.26mA
10 = 0.45mA
11 = 0.635mA
Values are scaled with AVDD.
Figures shown are based on
AVDD=1.8V.
MICSHORT_TH
R [1:0]
MICBIAS Short Circuit Button Push
Threshold
3:2
00
00 = 0.52mA
01 = 0.77mA
10 = 1.2mA
11 = 1.43mA
Values are scaled with AVDD.
Figures shown are based on
AVDD=1.8V.
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
MICDET_ENA
MICBIAS Current and Short Circuit
Detect Enable
1
0
0 = disabled
1 = enabled
Table 7 MICBIAS Current Detect
MICBIAS CURRENT DETECT FILTERING
The function of the filtering is to ensure that AC current spikes caused by ambient noise conditions
near the microphone do not lead to incorrect signalling of the microphone insertion/removal status or
the microphone hookswitch status.
Hysteresis on the current thresholds is provided; this means that a different current threshold is used
to detect microphone insertion and microphone removal. Similarly, a different current threshold is
used to detect hookswitch press and hookswtich release.
Digital filtering of the hookswitch status ensures that the MICBIAS Short Circuit detection event is
only signalled if the MICSHORT_THR threshold condition has been met for 10 consecutive
measurements.
In a typical application, microphone insertion would be detected when the MICBIAS current exceeds
the Current Detect threshold set by MICDET_THR.
When the MICDET_INV interrupt polarity bit is set to 0, then microphone insertion detection will cause
the MICDET_EINT interrupt status register to be set.
For detection of microphone removal, the MICDET_INV bit should be set to 1. When the
MICDET_INV interrupt polarity bit is set to 1, then microphone removal detection will cause the
MICDET_EINT interrupt status register to be set.
The detection of these events is bandwidth limited for best noise rejection, and is subject to detection
delay time tDET, as specified in the “Electrical Characteristics”. Provided that the MICDET_THR field
has been set appropriately, each insertion or removal event is guaranteed to be detected within the
delay time tDET
.
It is likely that the microphone socket contacts will have mechanical “bounce” when a microphone is
inserted or removed, and hence the resultant control signal will not be a clean logic level transition.
Since tDET has a range of values, it is possible that the interrupt will be generated before the
mechanical “bounce” has ceased. Hence after a mic insertion or removal has been detected, a time
delay should be applied before re-configuring the MICDET_INV bit. The maximum possible
mechanical bounce times for mic insertion and removal must be understood by the software
programmer.
Utilising a GPIO pin to monitor the steady state of the microphone detection function does not change
the timing of the detection mechanism, so there will also be a delay tDET before the signal changes
state. It may be desirable to implement de-bounce in the host processor when monitoring the state of
the GPIO signal.
Microphone hook switch operation is detected when the MICBIAS current exceeds the Short Circuit
Detect threshold set by MICSHORT_THR. Using the digital filtering, the hook switch detection event
is only signalled if the MICSHORT_THR threshold condition has been met for 10 consecutive
measurements.
When the MICSHRT_INV interrupt polarity bit is set to 0, then hook switch operation will cause the
MICSHRT_EINT interrupt status register to be set.
For detection of microphone removal, the MICSHRT_INV bit should be set to 1. When the
MICSHRT_INV interrupt polarity bit is set to 1, then hook switch release will cause the
MICSHRT_EINT interrupt status register to be set.
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The hook switch detection measurement frequency and the detection delay time tSHORT are detailed in
the “Electrical Characteristics” section.
The WM8903 Interrupt function is described in the “Interrupts” section. Example control sequences for
configuring the Interrupts functions for MICBIAS current detection events are described in the
“Applications Information” section.
A clock is required for the digital filtering function. This requires:
MCLK is present
CLK_SYS_ENA = 1
WSMD_CLK_ENA
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
System Clock enable
R22 (16h)
CLK_SYS_ENA
2
0
Clock Rates 2
0 = Disabled
1 = Enabled
R108 (6Ch)
WSMD_CLK_EN
A
Write Sequencer / Mic Detect Clock
Enable.
8
0
Write
Sequencer 0
0 = Disabled
1 = Enabled
Table 8 MICBIAS Current Detect Clocking
Any MICBIAS Current Detect event (accessory insertion/removal or hookswitch press/release) which
happens while one or more of the clocking criteria is not satisfied (for example during a low power
mode where the CPU has disabled MCLK) will still be detected, but only after the clocking conditions
are met. An example is illustrated in Figure 26, where the mic is inserted while MCLK is stopped.
Figure 26 MICBIAS Detection Events without MCLK
MICROPHONE HOOK SWITCH DETECTION
The possibility of spurious hook switch interrupts due to ambient noise conditions can be removed by
careful understanding of the microphone behaviour under extremely high sound pressure levels or
during mechanical shock, and by correct selection of the MICBIAS resistor value; these factors will
affect the level of the MICBIAS AC current spikes.
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In applications where the Current Detect threshold is close to the level of the current spikes, the
probability of false detections is reduced by the hysteresis and digital filtering described above.
Note that the filtering algorithm provides only limited rejection of very high current spikes at
frequencies less than or equal to the hook switch detect measurement frequency, or at frequencies
equal to harmonics of the hook switch detect measurement frequency.
The MICBIAS Hook Switch digital filtering is illustrated in Figure 27. Example control sequences for
configuring the Interrupts functions for MICBIAS current detection events are described in the
“Applications Information” section.
Figure 27 MICBIAS Hook Switch Detect Filtering
DIGITAL MICROPHONE INTERFACE
The WM8903 supports a two-channel digital microphone interface. The two-channel audio data is
multiplexed on the DMIC_DAT input and clocked by the DMIC_LR output.
The Digital Microphone Input, DMIC_DAT, is provided on the GPIO2/DMIC_DAT pin. The associated
clock, DMIC_LR, is provided on the GPIO1/DMIC_LR pin.
The Digital Microphone Input is selected as input by setting the ADC_DIG_MIC bit. When the Digital
Microphone Input is selected, the ADC input is bypassed.
The Digital Microphone Interface configuration is illustrated in Figure 28.
Note that that care must be taken to ensure that the respective digital logic levels of the microphone
are compatible with the digital input thresholds of the WM8903. The digital input thresholds are
referenced to DBVDD, as defined in “Electrical Characteristics”. It is recommended to power the
digital microphones from the same DBVDD supply as WM8903.
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Figure 28 Digital Microphone Interface Control
When GPIO1 is configured as DMIC_LR Clock output, the WM8903 outputs a clock which supports
Digital Mic operation at a multiple of the ADC sampling rate, in the range 1-3MHz. The ADC and
Record Path filters must be enabled and the ADC sampling rate must be set in order to ensure
correct operation of all DSP functions associated with the digital microphone. Volume control for the
Digital Microphone Interface signals is provided using the ADC Volume Control.
See “Analogue-to-Digital Converter (ADC)” for details of the ADC Enable and volume control
functions. See “General Purpose Input/Output (GPIO)” for details of configuring the DMIC_LR and
DMIC_DAT functions. See “Clocking and Sample Rates” for the details of the supported clocking
configurations.
When GPIO2/DMIC_DAT is configured as DMIC_DAT input, then this pin is the digital microphone
input. Up to two microphones can share this pin; the two microphones are interleaved as illustrated in
Figure 29.
The digital microphone interface requires that MIC1 transmits a data bit each time that DMIC_LR is
high, and MIC2 transmits when DMIC_LR is low. The WM8903 samples the digital microphone data
in the middle of each DMIC_LR clock phase. Each microphone must tri-state its data output when the
other microphone is transmitting.
Figure 29 Digital Microphone Interface Timing
The digital microphone interface control fields are described in Table 9.
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
R164 (A4h)
ADC_DIG_MIC
0
Enables Digital Microphone mode.
0 = Audio DSP input is from ADC
9
Clock Rate
Test 4
1 = Audio DSP input is from digital
microphone interface
Table 9 Digital Microphone Interface Control
Note that, in addition to setting the ADC_DIG_MIC bit as described in Table 9, the pins
GPIO1/DMIC_LR and GPIO2/DMIC_DAT must also be configured to provide the digital microphone
interface function. See “General Purpose Input/Output (GPIO)” for details.
ANALOGUE-TO-DIGITAL CONVERTER (ADC)
The WM8903 uses two 24-bit, 128x oversampled sigma-delta ADCs. The use of multi-bit feedback
and high oversampling rates reduces the effects of jitter and high frequency noise. An oversample
rate of 64x can also be supported - see “Clocking and Sample Rates” for details. The ADC full-scale
input level is proportional to AVDD - see “Electrical Characteristics”. Any input signal greater than full
scale may overload the ADC and cause distortion.
The ADCs are enabled by the ADCL_ENA and ADCR_ENA register bits.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R18 (12h)
ADCL_ENA
0
Left ADC Enable
1
Power
Management
6
0 = disabled
1 = enabled
ADCR_ENA
0
Right ADC Enable
0 = disabled
1 = enabled
0
Table 10 ADC Enable Control
ADC DIGITAL VOLUME CONTROL
The output of the ADCs can be digitally amplified or attenuated over a range from -71.625dB to
+17.625dB in 0.375dB steps. The volume of each channel can be controlled separately. The gain for
a given eight-bit code is detailed in Table 12.
The ADC_VU bit controls the loading of digital volume control data. When ADC_VU is set to 0, the
ADCL_VOL or ADCR_VOL control data is loaded into the respective control register, but does not
actually change the digital gain setting. Both left and right gain settings are updated when a 1 is
written to ADC_VU. This makes it possible to update the gain of both channels simultaneously.
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REGISTER
ADDRESS
BIT
LABEL
ADCVU
DEFAULT
DESCRIPTION
R36 (24h)
ADC Volume Update
8
N/A
ADC Digital
Volume Left
Writing a 1 to this bit causes left and
right ADC volume to be updated
simultaneously
(Write-Only Register)
Left ADC Digital Volume
00h = Mute
ADCL_VOL [7:0]
7:0
1100_0000
(0dB)
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h = 0dB
… (0.375dB steps)
EFh to FFh = +17.625dB
(See Table 12 for volume range)
ADC Volume Update
R37 (25h)
ADCVU
8
N/A
ADC Digital
Volume Right
Writing a 1 to this bit causes left and
right ADC volume to be updated
simultaneously
(Write-Only Register)
Right ADC Digital Volume
00h = Mute
ADCR_VOL [7:0]
7:0
1100_0000
(0dB)
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h = 0dB
… (0.375dB steps)
EFh to FFh = +17.625dB
(See Table 12 for volume range)
Table 11 ADC Digital Volume Control
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ADCL_VOL or
ADCL_VOL or
ADCL_VOL or
ADCL_VOL or
ADCR_VOL Volume (dB) ADCR_VOL Volume (dB) ADCR_VOL Volume (dB) ADCR_VOL Volume (dB)
0h
1h
MUTE
-71.625
-71.250
-70.875
-70.500
-70.125
-69.750
-69.375
-69.000
-68.625
-68.250
-67.875
-67.500
-67.125
-66.750
-66.375
-66.000
-65.625
-65.250
-64.875
-64.500
-64.125
-63.750
-63.375
-63.000
-62.625
-62.250
-61.875
-61.500
-61.125
-60.750
-60.375
-60.000
-59.625
-59.250
-58.875
-58.500
-58.125
-57.750
-57.375
-57.000
-56.625
-56.250
-55.875
-55.500
-55.125
-54.750
-54.375
-54.000
-53.625
-53.250
-52.875
-52.500
-52.125
-51.750
-51.375
-51.000
-50.625
-50.250
-49.875
-49.500
-49.125
-48.750
-48.375
40h
41h
42h
43h
44h
45h
46h
47h
48h
49h
4Ah
4Bh
4Ch
4Dh
4Eh
4Fh
50h
51h
52h
53h
54h
55h
56h
57h
58h
59h
5Ah
5Bh
5Ch
5Dh
5Eh
5Fh
60h
61h
62h
63h
64h
65h
66h
67h
68h
69h
6Ah
6Bh
6Ch
6Dh
6Eh
6Fh
70h
71h
72h
73h
74h
75h
76h
77h
78h
79h
7Ah
7Bh
7Ch
7Dh
7Eh
7Fh
-48.000
-47.625
-47.250
-46.875
-46.500
-46.125
-45.750
-45.375
-45.000
-44.625
-44.250
-43.875
-43.500
-43.125
-42.750
-42.375
-42.000
-41.625
-41.250
-40.875
-40.500
-40.125
-39.750
-39.375
-39.000
-38.625
-38.250
-37.875
-37.500
-37.125
-36.750
-36.375
-36.000
-35.625
-35.250
-34.875
-34.500
-34.125
-33.750
-33.375
-33.000
-32.625
-32.250
-31.875
-31.500
-31.125
-30.750
-30.375
-30.000
-29.625
-29.250
-28.875
-28.500
-28.125
-27.750
-27.375
-27.000
-26.625
-26.250
-25.875
-25.500
-25.125
-24.750
-24.375
80h
81h
82h
83h
84h
85h
86h
87h
88h
89h
8Ah
8Bh
8Ch
8Dh
8Eh
8Fh
90h
91h
92h
93h
94h
95h
96h
97h
98h
99h
9Ah
9Bh
9Ch
9Dh
9Eh
9Fh
A0h
A1h
A2h
A3h
A4h
A5h
A6h
A7h
A8h
A9h
AAh
ABh
ACh
ADh
AEh
AFh
B0h
B1h
B2h
B3h
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
BCh
BDh
BEh
BFh
-24.000
-23.625
-23.250
-22.875
-22.500
-22.125
-21.750
-21.375
-21.000
-20.625
-20.250
-19.875
-19.500
-19.125
-18.750
-18.375
-18.000
-17.625
-17.250
-16.875
-16.500
-16.125
-15.750
-15.375
-15.000
-14.625
-14.250
-13.875
-13.500
-13.125
-12.750
-12.375
-12.000
-11.625
-11.250
-10.875
-10.500
-10.125
-9.750
C0h
C1h
C2h
C3h
C4h
C5h
C6h
C7h
C8h
C9h
CAh
CBh
CCh
CDh
CEh
CFh
D0h
D1h
D2h
D3h
D4h
D5h
D6h
D7h
D8h
D9h
DAh
DBh
DCh
DDh
DEh
DFh
E0h
E1h
E2h
E3h
E4h
E5h
E6h
E7h
E8h
E9h
EAh
EBh
ECh
EDh
EEh
EFh
F0h
F1h
F2h
F3h
F4h
F5h
F6h
F7h
F8h
F9h
FAh
FBh
FCh
FDh
FEh
FFh
0.000
0.375
2h
0.750
3h
1.125
4h
1.500
5h
1.875
6h
2.250
7h
2.625
8h
3.000
9h
3.375
Ah
3.750
Bh
4.125
Ch
4.500
Dh
4.875
Eh
5.250
Fh
5.625
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
20h
21h
22h
23h
24h
25h
26h
27h
28h
29h
2Ah
2Bh
2Ch
2Dh
2Eh
2Fh
30h
31h
32h
33h
34h
35h
36h
37h
38h
39h
3Ah
3Bh
3Ch
3Dh
3Eh
3Fh
6.000
6.375
6.750
7.125
7.500
7.875
8.250
8.625
9.000
9.375
9.750
10.125
10.500
10.875
11.250
11.625
12.000
12.375
12.750
13.125
13.500
13.875
14.250
14.625
15.000
15.375
15.750
16.125
16.500
16.875
17.250
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
17.625
-9.375
-9.000
-8.625
-8.250
-7.875
-7.500
-7.125
-6.750
-6.375
-6.000
-5.625
-5.250
-4.875
-4.500
-4.125
-3.750
-3.375
-3.000
-2.625
-2.250
-1.875
-1.500
-1.125
-0.750
-0.375
Table 12 ADC Digital Volume Range
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HIGH-PASS FILTER (HPF)
A digital high-pass filter is applied by default to the ADC path to remove DC offsets. This filter can
also be programmed to remove low frequency noise in handheld applications (e.g. wind noise,
handling noise or mechanical vibration). This filter is controlled using the ADC_HPF_ENA and
ADC_HPF_CUT register bits (see Table 13).
In hi-fi mode the high pass filter is optimised for removing DC offsets without degrading the bass
response and has a cut-off frequency of 3.7Hz at fs=44.1kHz.
In voice mode the high pass filter is optimised for voice communication and it is recommended to
program the cut-off frequency below 300Hz (e.g. ADC_HPF_CUT=11 at fs=8kHz or
ADC_HPF_CUT=10 at fs=16kHz).
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R38 (26h)
ADC_HPF_CUT
[1:0]
ADC Digital High Pass Filter Cut-Off
Frequency (fc)
6:5
00
ADC Digital 0
00 = hi-fi mode (fc=4Hz at
fs=48kHz)
01 = Voice mode 1 (fc=127Hz at
fs=16kHz)
10 = Voice mode 2 (fc=130Hz at
fs=8kHz)
11 = Voice mode 3 (fc=267Hz at
fs=8kHz)
(Note: fc scales with sample rate fs.
See Table 14 for cut-off frequencies
at all supported sample rates)
ADC_HPF_ENA
ADC Digital High Pass Filter Enable
0 = disabled
4
1
1 = enabled
Table 13 ADC High-pass Filter Control Registers
Value of ADC_HPF_CUT bits
01 10
Cut-off frequency (Hz)
00
11
Sample
Rate (kHz)
8.000
11.025
16.000
22.050
24.000
32.000
44.100
48.000
88.200
96.000
0.7
0.9
1.3
1.9
2.0
2.7
3.7
4.0
7.4
8.0
64
130
178
258
354
386
514
707
770
1414
1540
267
367
88
127
175
190
253
348
379
696
758
532
733
798
1063
1464
1594
2928
3188
Table 14 ADC High-pass Filter Cut-off Frequencies
The high pass filter characteristics are shown in “Digital Filter Characteristics” section.
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ADC OVERSAMPLING RATIO (OSR)
The ADC oversampling rate is programmable to allow power consumption versus audio performance
trade-offs. The default oversampling rate is high for best performance; using the lower OSR setting
reduces ADC power consumption.
REGISTER
ADDRESS
R10 (0Ah)
BIT
LABEL
DEFAULT
DESCRIPTION
ADC Oversampling Ratio
0 = Low Power (64 x fs)
0
ADC_OSR128
1
Analogue ADC
0
1 = High Performance (128 x fs)
Note that the Low Power options is
not supported when
CLK_SYS_MODE=10
Table 15 ADC Oversampling Ratio
Note that the Low Power (64 x fs) oversampling option is not supported when CLK_SYS_MODE=10
(see “Clocking and Sample Rates”, Table 62).
DYNAMIC RANGE CONTROL (DRC)
The dynamic range controller (DRC) is a circuit which can be enabled in the digital data path of the
ADC. Its function is to adjust the signal gain in conditions where the input amplitude is unknown or
varies over a wide range, e.g. when recording from microphones built into a handheld system. The
DRC can apply Compression and Automatic Level Control to the signal path. It incorporates ‘anti-clip’
and ‘quick release’ features for handling transients in order to improve intelligibility in the presence of
loud impulsive noises.
The DRC is enabled as shown in Table 16.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
DRC enable
R40 (28h)
DRC 0
15
DRC_ENA
0
1 = enabled
0 = disabled
Table 16 DRC Enable
COMPRESSION/LIMITING CAPABILITIES
The DRC supports two different compression regions, specified by R0 and R1, separated by a “knee”
at input amplitude T. For signals above the knee, the compression slope R0 applies; for signals below
the knee, the compression slope R1 applies.
The overall DRC compression characteristic in “steady state” (i.e. where the input amplitude is near-
constant) is illustrated in Figure 30.
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Figure 30 DRC Compression Characteristic
The slope of R0 and R1 are determined by register fields DRC_R0_SLOPE_COMP and
DRC_R1_SLOPE_COMP respectively. A slope of 1 indicates constant gain in this region. A slope
less than 1 represents compression (i.e. a change in input amplitude produces only a smaller change
in output amplitude). A slope of 0 indicates that the target output amplitude is the same across a
range of input amplitudes; this is infinite compression.
The “knee” in Figure 30 is represented by T and Y, which are determined by register fields
DRC_THRESH_COMP and DRC_AMP_COMP respectively.
Parameter Y0, the output level for a 0dB input, is not specified directly, but can be calculated from the
other parameters, using the equation
Y0 = YT – (T * R0)
The DRC Compression parameters are defined in Table 17.
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DESCRIPTION
Compressor slope R0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
R42 (2Ah)
DRC 2
5:3
DRC_R0_SLOP
E_COMP [2:0]
100
000 = 1 (no compression)
001 = 1/2
010 = 1/4
011 = 1/8
100 = 1/16
101 = 0
110 = Reserved
111 = Reserved
Compressor slope R1
000 = 1 (no compression)
001 = 1/2
2:0
10:5
4:0
DRC_R1_SLOP
E_COMP [2:0]
000
010 = 1/4
011 = 1/8
100 = 0
101 = Reserved
11X = Reserved
Compressor threshold T (dB)
000000 = 0dB
000001 = -0.75dB
000010 = -1.5dB
… (-0.75dB steps)
111100 = -45dB
111101 = Reserved
11111X = Reserved
R43 (2Bh)
DRC 3
DRC_THRESH_
COMP [5:0]
000000
DRC_AMP_CO
MP [4:0]
00000
Compressor amplitude at threshold
YT (dB)
00000 = 0dB
00001 = -0.75dB
00010 = -1.5dB
… (-0.75dB steps)
11110 = -22.5dB
11111 = Reserved
Table 17 DRC Compression Control
GAIN LIMITS
The minimum and maximum gain applied by the DRC is set by register fields DRC_MINGAIN and
DRC_MAXGAIN. These limits can be used to alter the DRC response from that illustrated in Figure
30. If the range between maximum and minimum gain is reduced, then the extent of the dynamic
range control is reduced. The maximum gain prevents quiet signals (or silence) from being
excessively amplified.
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R41(29h)
DRC 1
DRC_MINGAIN
[1:0]
Minimum gain the DRC can use to
attenuate audio signals
3:2
00
00 = 0dB (default)
01 = -6dB
10 = -12dB
11 = -18dB
DRC_MAXGAIN
[1:0]
Maximum gain the DRC can use to
boost audio signals
1:0
01
00 = 12dB
01 = 18dB (default)
10 = 24dB
11 = 36dB
Table 18 DRC Gain Limits
DYNAMIC CHARACTERISTICS
The dynamic behaviour determines how quickly the DRC responds to changing signal levels. Note
that the DRC responds to the average (RMS) signal amplitude over a period of time.
The DRC_ATTACK_RATE determines how quickly the DRC gain decreases when the signal
amplitude is high. The DRC_DECAY_RATE determines how quickly the DRC gain increases when
the signal amplitude is low.
These register fields are described in Table 19. Note that the register defaults are suitable for general
purpose microphone use.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R41 (29h)
DRC 1
15:12
DRC_ATTACK_
RATE [3:0]
0011
Gain attack rate (seconds/6dB)
0000 = Reserved
0001 = 182µs
0010 = 363µs
0011 = 726µs (default)
0100 = 1.45ms
0101 = 2.9ms
0110 = 5.8ms
0111 = 11.6ms
1000 = 23.2ms
1001 = 46.4ms
1010 = 92.8ms
1011-1111 = Reserved
Gain decay rate (seconds/6dB)
0000 = 186ms
11:8
DRC_DECAY_R
ATE [3:0]
0010
0001 = 372ms
0010 = 743ms (default)
0011 = 1.49s
0100 = 2.97s
0101 = 5.94s
0110 = 11.89s
0111 = 23.78s
1000 = 47.56s
1001-1111 = Reserved
Table 19 DRC Attack and Decay Rates
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Note:
For detailed information about DRC attack and decay rates, please see Wolfson application note
WAN0247.
ANTI-CLIP CONTROL
The DRC includes an Anti-Clip feature to avoid signal clipping when the input amplitude rises very
quickly. This feature uses a feed-forward technique for early detection of a rising signal level. Signal
clipping is avoided by dynamically increasing the gain attack rate when required. The Anti-Clip feature
is enabled using the DRC_ANTICLIP_ENA bit.
Note that the feed-forward processing increases the latency in the input signal path. For low-latency
applications (e.g. telephony), it may be desirable to reduce the delay, although this will also reduce
the effectiveness of the anti-clip feature. The latency is determined by the DRC_FF_DELAY bit. If
necessary, the latency can be minimised by disabling the anti-clip feature altogether.
The DRC Anti-Clip control bits are described in Table 20.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R40 (28h)
DRC 0
DRC_FF_DELAY
Feed-forward delay for anti-clip
feature
5
1
0 = 5 samples
1 = 9 samples
Time delay can be calculated as 5/fs
or 9/ fs, where fs is the sample rate.
DRC_ANTICLIP_
ENA
1
1
Anti-clip enable
0 = disabled
1 = enabled
Table 20 DRC Anti-Clip Control
Note that the Anti-Clip feature operates entirely in the digital domain, i.e. after the ADC. It cannot be
used to prevent signal clipping in the analogue domain (e.g. in the input PGAs or ADCs), nor in the
source signal. Analogue clipping can only be prevented by reducing the analogue signal gain or by
adjusting the source signal.
QUICK RELEASE CONTROL
The DRC includes a Quick-Release feature to handle short transient peaks that are not related to the
intended source signal. For example, in handheld microphone recording, transient signal peaks
sometimes occur due to user handling, key presses or accidental tapping against the microphone.
The Quick Release feature ensures that these transients do not cause the intended signal to be
masked by the longer time constants of DRC_DECAY_RATE.
The Quick-Release feature is enabled by setting the DRC_QR_ENA bit. When this bit is enabled, the
DRC measures the crest factor (peak to RMS ratio) of the input signal. A high crest factor is indicative
of a transient peak that may not be related to the intended source signal. If the crest factor exceeds
the level set by DRC_THRESH_QR, then the normal decay rate (DRC_DECAY_RATE) is ignored
and a faster decay rate (DRC_RATE_QR) is used instead.
The DRC Quick-Release control bits are described in Table 21.
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R40 (28h)
DRC 0
DRC_QR_ENA
Quick release enable
2
1
0 = disabled
1 = enabled
R41 (29h)
DRC 1
DRC_THRESH_
QR [1:0]
Quick release crest factor threshold
00 = 12dB
7:6
5:4
01
00
01 = 18dB (default)
10 = 24dB
11 = 30dB
DRC_RATE_QR
[1:0]
Quick release decay rate
(seconds/6dB)
00 = 0.725ms (default)
01 = 1.45ms
10 = 5.8ms
11 = Reserved
Table 21 DRC Quick-Release Control
GAIN SMOOTHING
The DRC includes a gain smoothing filter in order to prevent gain ripples. A programmable level of
hysteresis is also used to control the DRC gain. This improves the handling of very low frequency
input signals whose period is close to the DRC attack/decay time. DRC Gain Smoothing is enabled by
default and it is recommended to use the default register settings.
The extent of the gain smoothing filter may be adjusted or disabled using the control fields described
in Table 22.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R40 (28h)
DRC 0
DRC_THRESH_
HYST [1:0]
Gain smoothing hysteresis
threshold
12:11
01
00 = Low
01 = Medium (recommended)
10 = High
11 = Reserved
DRC_SMOOTH_
ENA
Gain smoothing enable
0 = disabled
3
0
1
1
1 = enabled
DRC_HYST_EN
A
Gain smoothing hysteresis enable
0 = disabled
1 = enabled
Table 22 DRC Gain Smoothing
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INITIALISATION
When the DRC is initialised, the gain is set to the level determined by the DRC_STARTUP_GAIN
register field. The default setting is 0dB, but values from -18dB to +36dB are available, as described
in Table 23.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R40 (28h)
DRC 0
DRC_STARTUP_
GAIN [4:0]
Initial gain at DRC startup
00000 = -18dB
00001 = -15dB
00010 = -12dB
00011 = -9dB
10:6
00110
00100 = -6dB
00101 = -3dB
00110 = 0dB (default)
00111 = 3dB
01000 = 6dB
01001 = 9dB
01010 = 12dB
01011 = 15dB
01100 = 18dB
01101 = 21dB
01110 = 24dB
01111 = 27dB
10000 = 30dB
10001 = 33dB
10010 = 36dB
10011 to 11111 = Reserved
Table 23 DRC Initialisation
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DIGITAL MIXING
The ADC and DAC data can be combined in various ways to support a range of different usage
modes.
Data from either of the two ADCs can be routed to either the left or the right channel of the digital
audio interface. In addition, data from either of the digital audio interface channels can be routed to
either the left or the right DAC. See “Digital Audio Interface” for more information on the audio
interface.
The WM8903 provides a Dynamic Range Control (DRC) feature, which can apply compression and
gain adjustment in the digital domain to the ADC signal path. This is effective in controlling signal
levels under conditions where input amplitude is unknown or varies over a wide range.
The DACs can be configured as a mono mix of the two audio channels. Digital sidetone from the
ADCs can also be selectively mixed into the DAC output path.
DIGITAL MIXING PATHS
Figure 31 shows the digital mixing paths available in the WM8903 digital core.
Figure 31 Digital Mixing Paths
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The polarity of each ADC output signal can be changed under software control using the
ADCL_DATINV and ADCR_DATINV register bits. The AIFADCL_SRC and AIFADCR_SRC register
bits may be used to select which ADC is used for the left and right digital audio interface data. These
register bits are described in Table 24.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R24 (18h)
AIFADCL_SRC
Left Digital Audio channel source
7
0
Audio
Interface 0
0 = Left ADC data is output on left
channel
1 = Right ADC data is output on left
channel
AIFADCR_SRC
Right Digital Audio channel source
6
1
0 = Left ADC data is output on right
channel
1 = Right ADC data is output on
right channel
R38 (26h)
ADCL_DATINV
ADCR_DATINV
Left ADC Invert
1
0
0
0
ADC Digital 0
0 = Left ADC output not inverted
1 = Left ADC output inverted
Right ADC Invert
0 = Right ADC output not inverted
1 = Right ADC output inverted
Table 24 ADC Routing and Control
The input data source for each DAC can be changed under software control using register bits
DACL_SRC and DACR_SRC. The polarity of each DAC input may also be modified using register
bits DACL_DATINV and DACR_DATINV. These register bits are described in Table 25.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R24 (18h)
DACL_DATINV
Left DAC Invert
12
0
Audio
Interface 0
0 = Left DAC output not inverted
1 = Left DAC output inverted
Right DAC Invert
DACR_DATINV
AIFDACL_SRC
11
5
0
0
0 = Right DAC output not inverted
1 = Right DAC output inverted
Left DAC Data Source Select
0 = Left DAC outputs left channel
data
1 = Left DAC outputs right channel
data
AIFDACR_SRC
Right DAC Data Source Select
4
1
0 = Right DAC outputs left channel
data
1 = Right DAC outputs right channel
data
Table 25 DAC Routing and Control
DAC INTERFACE VOLUME BOOST
A digital gain function is available at the audio interface to boost the DAC volume when a small signal
is received on DACDAT. This is controlled using register bits DAC_BOOST [1:0]. To prevent clipping
at the DAC input, this function should not be used when the boosted DAC data is expected to be
greater than 0dBFS.
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The digital interface volume is controlled as shown in Table 26.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R24 (18h)
DAC_BOOST
[1:0]
DAC Input Volume Boost
00 = 0dB
10:9
00
Audio
Interface 0
01 = +6dB (Input data must not
exceed -6dBFS)
10 = +12dB (Input data must not
exceed -12dBFS)
11 = +18dB (Input data must not
exceed -18dBFS)
Table 26 DAC Interface Volume Boost
DIGITAL SIDETONE
Digital sidetone mixing (from ADC output into DAC input) is available when ADCs and DACs are
operating at the same sample rate. Digital data from either left or right ADC can be mixed with the
audio interface data on the left and right DAC channels. Sidetone data is taken from the ADC
high-pass filter output, to reduce low frequency noise in the sidetone (e.g. wind noise or mechanical
vibration).
When using the digital sidetone, it is recommended that the ADCs are enabled before un-muting the
DACs to prevent pop noise. The DAC volumes and sidetone volumes should be set to an appropriate
level to avoid clipping at the DAC input.
When digital sidetone is used, it is recommended that the Charge Pump operates in Register Control
mode only (CP_DYN_PWR = 0). See “Charge Pump” for details.
The digital sidetone is controlled as shown in Table 27.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R32 (20h)
ADCL_DAC_SV
OL [3:0]
Left Digital Sidetone Volume
0000 = -36dB
11:8
0000
DAC Digital 0
0001 = -33dB
(… 3dB steps)
1011 = -3dB
11XX = 0dB
(See Table 28 for volume range)
Right Digital Sidetone Volume
0000 = -36dB
ADCR_DAC_SV
OL [3:0]
7:4
0000
0001 = -33dB
(… 3dB steps)
1011 = -3dB
11XX = 0dB
(See Table 28 for volume range)
Left DAC Digital Sidetone Source
00 = No sidetone
01 = Left ADC
ADC_TO_DACL
[1:0]
3:2
1:0
00
00
10 = Right ADC
11 = Reserved
ADC_TO_DACR
[1:0]
Right DAC Digital Sidetone Source
00 = No sidetone
01 = Left ADC
10 = Right ADC
11 = Reserved
Table 27 Digital Sidetone Control
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The digital sidetone volume settings are shown in Table 28.
ADCL_DAC_SVOL
SIDETONE VOLUME
OR
ADCR_DAC_SVOL
0000
-36
-33
-30
-27
-24
-21
-18
-15
-12
-9
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
-6
1011
-3
1100
0
1101
0
1110
0
1111
0
Table 28 Digital Sidetone Volume
DIGITAL-TO-ANALOGUE CONVERTER (DAC)
The WM8903 DACs receive digital input data from the DACDAT pin and via the digital sidetone path
(see “Digital Mixing” section). The digital audio data is converted to oversampled bit streams in the
on-chip, true 24-bit digital interpolation filters. The bitstream data enters two multi-bit, sigma-delta
DACs, which convert them to high quality analogue audio signals. The Wolfson SmartDAC™
architecture offers reduced power consumption, whilst also delivering a reduction in high frequency
noise and sensitivity to clock jitter. It also uses a Dynamic Element Matching technique for high
linearity and low distortion.
The analogue outputs from the DACs can then be mixed with other analogue inputs before being sent
to the analogue output pins (see “Output Signal Path”).
The DACs are enabled by the DACL_ENA and DACR_ENA register bits.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R18 (12h)
DACL_ENA
Left DAC Enable
3
0
Power
Management
6
0 = DAC disabled
1 = DAC enabled
Right DAC Enable
0 = DAC disabled
1 = DAC enabled
DACR_ENA
2
0
Table 29 DAC Enable Control
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DAC DIGITAL VOLUME CONTROL
The output level of each DAC can be controlled digitally over a range from -71.625dB to 0dB in
0.375dB steps. The level of attenuation for an eight-bit code is detailed in Table 31.
The DAC_VU bit controls the loading of digital volume control data. When DAC_VU is set to 0, the
DACL_VOL or DACR_VOL control data is loaded into the respective control register, but does not
actually change the digital gain setting. Both left and right gain settings are updated when a 1 is
written to DAC_VU. This makes it possible to update the gain of both channels simultaneously.
REGISTER
ADDRESS
BIT
LABEL
DACVU
DEFAULT
DESCRIPTION
R30 (1Eh)
DAC Volume Update
8
N/A
DAC Digital
Volume Left
Writing a 1 to this bit causes left and
right DAC volume to be updated
simultaneously
(Write-Only Register)
Left DAC Digital Volume
00h = Mute
DACL_VOL [7:0]
7:0
1100_0000
(0dB)
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h = 0dB
… (0.375dB steps)
EFh to FFh = +17.625dB
(See Table 31 for volume range)
DAC Volume Update
R31 (1Fh)
DACVU
8
N/A
DAC Digital
Volume Right
Writing a 1 to this bit causes left and
right DAC volume to be updated
simultaneously
(Write-Only Register)
Right DAC Digital Volume
00h = Mute
DACR_VOL [7:0]
7:0
1100_0000
(0dB)
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h = 0dB
… (0.375dB steps)
EFh to FFh = +17.625dB
(See Table 31 for volume range)
Table 30 DAC Digital Volume Control
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DACL_VOL or
DACL_VOL or
DACL_VOL or
DACL_VOL or
DACR_VOL Volume (dB) DACR_VOL Volume (dB) DACR_VOL Volume (dB) DACR_VOL Volume (dB)
0h
1h
MUTE
-71.625
-71.250
-70.875
-70.500
-70.125
-69.750
-69.375
-69.000
-68.625
-68.250
-67.875
-67.500
-67.125
-66.750
-66.375
-66.000
-65.625
-65.250
-64.875
-64.500
-64.125
-63.750
-63.375
-63.000
-62.625
-62.250
-61.875
-61.500
-61.125
-60.750
-60.375
-60.000
-59.625
-59.250
-58.875
-58.500
-58.125
-57.750
-57.375
-57.000
-56.625
-56.250
-55.875
-55.500
-55.125
-54.750
-54.375
-54.000
-53.625
-53.250
-52.875
-52.500
-52.125
-51.750
-51.375
-51.000
-50.625
-50.250
-49.875
-49.500
-49.125
-48.750
-48.375
40h
41h
42h
43h
44h
45h
46h
47h
48h
49h
4Ah
4Bh
4Ch
4Dh
4Eh
4Fh
50h
51h
52h
53h
54h
55h
56h
57h
58h
59h
5Ah
5Bh
5Ch
5Dh
5Eh
5Fh
60h
61h
62h
63h
64h
65h
66h
67h
68h
69h
6Ah
6Bh
6Ch
6Dh
6Eh
6Fh
70h
71h
72h
73h
74h
75h
76h
77h
78h
79h
7Ah
7Bh
7Ch
7Dh
7Eh
7Fh
-48.000
-47.625
-47.250
-46.875
-46.500
-46.125
-45.750
-45.375
-45.000
-44.625
-44.250
-43.875
-43.500
-43.125
-42.750
-42.375
-42.000
-41.625
-41.250
-40.875
-40.500
-40.125
-39.750
-39.375
-39.000
-38.625
-38.250
-37.875
-37.500
-37.125
-36.750
-36.375
-36.000
-35.625
-35.250
-34.875
-34.500
-34.125
-33.750
-33.375
-33.000
-32.625
-32.250
-31.875
-31.500
-31.125
-30.750
-30.375
-30.000
-29.625
-29.250
-28.875
-28.500
-28.125
-27.750
-27.375
-27.000
-26.625
-26.250
-25.875
-25.500
-25.125
-24.750
-24.375
80h
81h
82h
83h
84h
85h
86h
87h
88h
89h
8Ah
8Bh
8Ch
8Dh
8Eh
8Fh
90h
91h
92h
93h
94h
95h
96h
97h
98h
99h
9Ah
9Bh
9Ch
9Dh
9Eh
9Fh
A0h
A1h
A2h
A3h
A4h
A5h
A6h
A7h
A8h
A9h
AAh
ABh
ACh
ADh
AEh
AFh
B0h
B1h
B2h
B3h
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
BCh
BDh
BEh
BFh
-24.000
-23.625
-23.250
-22.875
-22.500
-22.125
-21.750
-21.375
-21.000
-20.625
-20.250
-19.875
-19.500
-19.125
-18.750
-18.375
-18.000
-17.625
-17.250
-16.875
-16.500
-16.125
-15.750
-15.375
-15.000
-14.625
-14.250
-13.875
-13.500
-13.125
-12.750
-12.375
-12.000
-11.625
-11.250
-10.875
-10.500
-10.125
-9.750
C0h
C1h
C2h
C3h
C4h
C5h
C6h
C7h
C8h
C9h
CAh
CBh
CCh
CDh
CEh
CFh
D0h
D1h
D2h
D3h
D4h
D5h
D6h
D7h
D8h
D9h
DAh
DBh
DCh
DDh
DEh
DFh
E0h
E1h
E2h
E3h
E4h
E5h
E6h
E7h
E8h
E9h
EAh
EBh
ECh
EDh
EEh
EFh
F0h
F1h
F2h
F3h
F4h
F5h
F6h
F7h
F8h
F9h
FAh
FBh
FCh
FDh
FEh
FFh
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
2h
3h
4h
5h
6h
7h
8h
9h
Ah
Bh
Ch
Dh
Eh
Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
20h
21h
22h
23h
24h
25h
26h
27h
28h
29h
2Ah
2Bh
2Ch
2Dh
2Eh
2Fh
30h
31h
32h
33h
34h
35h
36h
37h
38h
39h
3Ah
3Bh
3Ch
3Dh
3Eh
3Fh
-9.375
-9.000
-8.625
-8.250
-7.875
-7.500
-7.125
-6.750
-6.375
-6.000
-5.625
-5.250
-4.875
-4.500
-4.125
-3.750
-3.375
-3.000
-2.625
-2.250
-1.875
-1.500
-1.125
-0.750
-0.375
Table 31 DAC Digital Volume Range
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DAC SOFT MUTE AND SOFT UN-MUTE
The WM8903 has a soft mute function. When enabled, this gradually attenuates the volume of the
DAC output. When soft mute is disabled, the gain will either gradually ramp back up to the digital gain
setting, or return instantly to the digital gain setting, depending on the DAC_MUTEMODE register bit.
The DAC is not muted by default (DAC_MUTE = 0). To mute the DAC, this function must be enabled
by setting DAC_MUTE to 1.
Soft Mute Mode would typically be enabled (DAC_MUTEMODE = 1) when using DAC_MUTE during
playback of audio data so that when DAC_MUTE is subsequently disabled, the sudden volume
increase will not create pop noise by jumping immediately to the previous volume level (e.g. resuming
playback after pausing during a track).
Soft Mute Mode would typically be disabled (DAC_MUTEMODE = 0) when un-muting at the start of a
music file, in order that the first part of the track is not attenuated (e.g. when starting playback of a
new track, or resuming playback after pausing between tracks).
DAC muting and un-muting using volume control bits
DACL_VOL and DACR_VOL.
DAC muting and un-muting using the DAC_MUTE bit.
If soft Mute Mode is not enabled (DAC_MUTEMODE = 0):
Setting the DAC_MUTE bit causes the volume to ramp down
at a rate controlled by DAC_MUTERATE.
Clearing the DAC_MUTE bit causes the volume to return to
the un-muted level immediately.
DAC muting and un-muting using the DAC_MUTE bit.
If soft Mute Mode is enabled (DAC_MUTEMODE = 1):
Setting the DAC_MUTE bit causes the volume to ramp down.
Clearing the DAC_MUTE bit causes the volume to ramp up to
the un-muted level at a rate controlled by DAC_MUTERATE.
Figure 32 DAC Mute Control
The volume ramp rate during soft mute and un-mute is controlled by the DAC_MUTERATE bit. Ramp
rates of fs/32 and fs/2 can be selected, as shown in Table 32. The ramp rate determines the rate at
which the volume is increased or decreased. The actual ramp time depends on the extent of the
difference between the muted and un-muted volume settings.
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
R33 (21h)
DAC_MUTERA
TE
DAC Soft Mute Ramp Rate
10
0
DAC Digital 1
0 = Fast ramp (fs/2, maximum ramp
time is 10.7ms at fs=48k)
1 = Slow ramp (fs/32, maximum ramp
time is 171ms at fs=48k)
DAC_MUTEM
ODE
DAC Soft Mute Mode
9
0
0 = Disabling soft-mute
(DAC_MUTE=0) will cause the DAC
volume to change immediately to
DACL_VOL and DACR_VOL settings
1 = Disabling soft-mute
(DAC_MUTE=0) will cause the DAC
volume to ramp up gradually to the
DACL_VOL and DACR_VOL settings
DAC_MUTE
DAC Soft Mute Control
0 = DAC Un-mute
1 = DAC Mute
3
0
Table 32 DAC Soft-Mute Control
DAC MONO MIX
A DAC digital mono-mix mode can be enabled using the DAC_MONO register bit. This mono mix will
be output on whichever DAC is enabled. To prevent clipping, a -6dB attenuation is automatically
applied to the mono mix.
The mono mix is only supported when one or other DAC is disabled. When the mono mix is selected,
then the mono mix is output on the enabled DAC only; there is no output from the disabled DAC. If
DACL_ENA and DACR_ENA are both set, then stereo operation applies.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R33 (21h)
DAC_MONO
DAC Mono Mix
12
0
DAC Digital 1
0 = Stereo
1 = Mono (Mono mix output on
enabled DAC)
Table 33 DAC Mono Mix
DAC DE-EMPHASIS
Digital de-emphasis can be applied to the DAC playback data (e.g. when the data comes from a CD
with pre-emphasis used in the recording). De-emphasis filtering is available for sample rates of
48kHz, 44.1kHz and 32kHz. See “Digital Filter Characteristics” for details of de-emphasis filter
characteristics.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R33 (21h)
DAC Digital 1
DEEMPH [1:0]
DAC De-Emphasis Control
00 = No de-emphasis
2:1
00
01 = 32kHz sample rate
10 = 44.1kHz sample rate
11 = 48kHz sample rate
Table 34 DAC De-Emphasis Control
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DAC SLOPING STOPBAND FILTER
Two DAC filter types are available, selected by the register bit DAC_SB_FILT. When operating at
sample rates <= 24kHz (e.g. during voice communication) it is recommended that the sloping
stopband filter type is selected (DAC_SB_FILT=1) to reduce out-of-band noise which can be audible
at low DAC sample rates. See “Digital Filter Characteristics” for details of DAC filter characteristics.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R33 (21h)
DAC Digital 1
DAC_SB_FILT
Selects DAC filter characteristics
0 = Normal mode
11
0
1 = Sloping stopband mode
(recommended when fs 24kHz
Table 35 DAC Sloping Stopband Filter
DAC BIAS CONTROL
The analogue circuits within the DAC use the Master bias current (see “Reference Voltages and
Master Bias”). The DAC bias currents can also be reduced using the DACBIAS_SEL and
DACVMID_SEL fields as described in Table 36. These can be used to reduce power consumption,
but may have a marginal impact on audio performance in some usage modes.
The DAC bias currents can be increased using the DAC_BIAS_BOOST field. Setting this bit doubles
the bias level of DACBIAS_SEL and DACVMID_BIAS_SEL. This offers a performance improvement,
but also an increase in power consumption.
Note that the increased DAC VMID buffer bias is unlikely to give better performance; when
DAC_BIAS_BOOST is set, it is recommended to set DACVMID_BIAS_SEL = 01 in order to restore
the Normal DAC VMID buffer bias level.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R8 (08h)
DAC_BIAS_BOO
ST
DAC Bias boost
5
0
Analogue
DAC 0
0 = Disable
1 = Enable
When DAC Bias boost is enabled, the
bias selected by DACBIAS_SEL and
DACVMID_BIAS_SEL are both
doubled.
DACBIAS_SEL
DAC bias current select
00 = Normal bias
4:3
2:1
00
00
01 = Normal bias x 0.5
10 = Normal bias x 0.66
11 = Normal bias x 0.75
DAC VMID buffer bias select
00 = Normal bias
DACVMID_BIAS_
SEL
01 = Normal bias x 0.5
10 = Normal bias x 0.66
11 = Normal bias x 0.75
Table 36 DAC Bias Control
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DAC OVERSAMPLING RATIO (OSR)
The DAC oversampling rate is programmable to allow power consumption versus audio performance
trade-offs. The default oversampling rate is low for reduced power consumption; using the higher
OSR setting improves the DAC signal-to-noise performance.
REGISTER
ADDRESS
R33 (21h)
BIT
LABEL
DEFAULT
DESCRIPTION
DAC Oversampling Control
0
DAC_OSR
0
DAC Digital 1
0 = Low power (normal oversample)
1 = High performance (double rate)
Table 37 DAC Oversampling Control
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OUTPUT SIGNAL PATH
The outputs HPOUTL and LINEOUTL are derived from the Left Mixer, whilst the HPOUTR and
LINEOUTR are derived from the Right Mixer. These mixers allow the stereo DAC and stereo bypass
signals to be mixed together for the Headphone and Line outputs.
A feedback path for common mode noise rejection is provided at HPGND and LINEGND for the
Headphone and Line outputs respectively. This pin must be connected to ground for normal
operation.
The outputs LOP/LON and ROP/RON are differential line outputs derived from the Left Speaker mixer
and Right Speaker mixer respectively.
Each analogue output can be separately enabled; independent volume control is also provided for
each output. The output signal paths and associated control registers are illustrated in Figure 33. See
“Analogue Outputs” for details of the external connections to these outputs.
Figure 33 Output Signal Path and Control Registers
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OUTPUT SIGNAL PATHS ENABLE
The output mixers and drivers can be independently enabled and disabled using the register bits
described in Table 38.
Note that the Headphone Outputs and Line Outputs are also controlled by fields located within
Register R90 and R94, which provide suppression of pops & clicks when enabling and disabling
these signal paths. These registers are described in the following “Headphone / Line Output Signal
Paths Enable” section.
Under recommended usage conditions, the pop suppression control bits will be configured by
scheduling the default Start-Up and Shut-Down sequences as described in the “Control Write
Sequencer” section. In these cases, the user does not need to set the register fields in R13, R14,
R15, R90 and R94 directly.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R13 (0Dh)
MIXOUTL_ENA
Left Output Mixer Enable
0 = disabled
1
0
Power
Management 1
1 = enabled
MIXOUTR_ENA
HPL_PGA_ENA
HPR_PGA_ENA
Right Output Mixer Enable
0 = disabled
0
1
0
1
0
1
0
1
0
0
0
0
0
0
0
0
0
0
1 = enabled
R14 (0Eh)
Left Headphone Output Enable
0 = disabled
Power
Management 2
1 = enabled
Right Headphone Output Enable
0 = disabled
1 = enabled
R15 (0Fh)
LINEOUTL_PGA_
ENA
Left Line Output Enable
0 = disabled
Power
Management 3
1 = enabled
LINEOUTR_PGA
_ENA
Right Line Output Enable
0 = disabled
1 = enabled
R16 (10h)
MIXSPKL_ENA
MIXSPKR_ENA
SPKL_ENA
Left Speaker Mixer Enable
0 = disabled
Power
Management 4
1 = enabled
Right Speaker Mixer Enable
0 = disabled
1 = enabled
R17 (11h)
Left Speaker Output Enable
0 = disabled
Power
Management 5
1 = enabled
SPKR_ENA
Right Speaker Output Enable
0 = disabled
1 = enabled
Table 38 Output Signal Paths Enable
To enable the output PGAs and mixers, the reference voltage VMID and the bias current must also be
enabled. See “Reference Voltages and Master Bias” for details of the associated controls VMID_RES
and BIAS_ENA.
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HEADPHONE / LINE OUTPUT SIGNAL PATHS ENABLE
The Headphone / Line output paths can be actively discharged to AGND through internal resistors if
desired. This is desirable at start-up in order to achieve a known output stage condition prior to
enabling the VMID reference voltage. This is also desirable in shutdown to prevent the external
connections from being affected by the internal circuits. The ground-referenced Headphone outputs
and Line outputs are shorted to AGND by default; the short circuit is removed on each of these paths
by setting the applicable fields HPL_RMV_SHORT, HPR_RMV_SHORT, LINEOUTL_RMV_SHORT
or LINEOUTR_RMV_SHORT.
The ground-referenced Headphone output and Line output drivers are designed to suppress pops
and clicks when enabled or disabled. However, it is necessary to control the drivers in accordance
with a defined sequence in start-up and shut-down to achieve the pop suppression. It is also
necessary to schedule the DC Servo offset correction at the appropriate point in the sequence (see
“DC Servo”). Table 39 and Table 40 describe the recommended sequences for enabling and
disabling these output drivers.
SEQUENCE
HEADPHONE ENABLE
HPL_ENA = 1
LINEOUT ENABLE
LINEOUTL_ENA = 1
Step 1
Step 2
Step 3
Step 4
Step 5
HPR_ENA = 1
LINEOUTR_ENA = 1
HPL_ENA_DLY = 1
HPR_ENA_DLY = 1
LINEOUTL_ENA_DLY = 1
LINEOUTR_ENA_DLY = 1
DC offset correction
DC offset correction
HPL_ENA_OUTP = 1
HPR_ENA_OUTP = 1
HPL_RMV_SHORT = 1
HPR_RMV_SHORT = 1
LINEOUTL_ENA_OUTP = 1
LINEOUTR_ENA_OUTP = 1
LINEOUTL_RMV_SHORT = 1
LINEOUTR_RMV_SHORT = 1
Table 39 Headphone / Line Output Enable Sequence
SEQUENCE
HEADPHONE DISABLE
HPL_RMV_SHORT = 0
HPR_RMV_SHORT = 0
HPL_ENA = 0
LINEOUT DISABLE
LINEOUTL_RMV_SHORT = 0
LINEOUTR_RMV_SHORT = 0
LINEOUTL_ENA = 0
Step 1
Step 2
HPL_ENA_DLY = 0
HPL_ENA_OUTP = 0
HPR_ENA = 0
LINEOUTL_ENA_DLY = 0
LINEOUTL_ENA_OUTP = 0
LINEOUTR_ENA = 0
HPR_ENA_DLY = 0
HPR_ENA_OUTP = 0
LINEOUTR_ENA_DLY = 0
LINEOUTR_ENA_OUTP = 0
Table 40 Headphone / Line Output Disable Sequence
The registers relating to Headphone / Line Output pop suppression control are defined in Table 41.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R90 (5Ah)
HPL_RMV_SHOR
T
Removes HPL short
7
0
Analogue
HP 0
0 = HPL short enabled
1 = HPL short removed
For normal operation, this bit should
be set as the final step of the HPL
Enable sequence.
HPL_ENA_OUTP
Enables HPL output stage
0 = Disabled
6
0
1 = Enabled
For normal operation, this bit should
be set to 1 after the DC offset
cancellation has been scheduled.
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
HPL_ENA_DLY
Enables HPL intermediate stage
0 = Disabled
5
0
1 = Enabled
For normal operation, this bit should
be set to 1 after the output signal path
has been configured, and before DC
offset cancellation is scheduled. This
bit should be set with at least 20us
delay after HPL_ENA.
HPL_ENA
Enables HPL input stage
0 = Disabled
4
3
2
1
0
0
0
0
1 = Enabled
For normal operation, this bit should
be set as the first step of the HPL
Enable sequence.
HPR_RMV_SHO
RT
Removes HPR short
0 = HPR short enabled
1 = HPR short removed
For normal operation, this bit should
be set as the final step of the HPR
Enable sequence.
HPR_ENA_OUTP
HPR_ENA_DLY
Enables HPR output stage
0 = Disabled
1 = Enabled
For normal operation, this bit should
be set to 1 after the DC offset
cancellation has been scheduled.
Enables HPR intermediate stage
0 = Disabled
1 = Enabled
For normal operation, this bit should
be set to 1 after the output signal path
has been configured, and before DC
offset cancellation is scheduled. This
bit should be set with at least 20us
delay after HPR_ENA.
HPR_ENA
Enables HPR input stage
0 = Disabled
0
0
1 = Enabled
For normal operation, this bit should
be set as the first step of the HPR
Enable sequence.
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R94 (5Eh)
LINEOUTL_RMV_
SHORT
Removes LINEOUTL short
0 = LINEOUTL short enabled
1 = LINEOUTL short removed
7
0
Analogue
Lineout 0
For normal operation, this bit should
be set as the final step of the
LINEOUTL Enable sequence.
LINEOUTL_ENA_
OUTP
Enables LINEOUTL output stage
0 = Disabled
6
5
0
0
1 = Enabled
For normal operation, this bit should
be set to 1 after the DC offset
cancellation has been scheduled.
LINEOUTL_ENA_
DLY
Enables LINEOUTL intermediate
stage
0 = Disabled
1 = Enabled
For normal operation, this bit should
be set to 1 after the output signal path
has been configured, and before DC
offset cancellation is scheduled. This
bit should be set with at least 20us
delay after LINEOUTL_ENA.
LINEOUTL_ENA
Enables LINEOUTL input stage
0 = Disabled
4
3
2
1
0
0
0
0
1 = Enabled
For normal operation, this bit should
be set as the first step of the
LINEOUTL Enable sequence.
LINEOUTR_RMV
_SHORT
Removes LINEOUTR short
0 = LINEOUTR short enabled
1 = LINEOUTR short removed
For normal operation, this bit should
be set as the final step of the
LINEOUTR Enable sequence.
LINEOUTR_ENA_
OUTP
Enables LINEOUTR output stage
0 = Disabled
1 = Enabled
For normal operation, this bit should
be set to 1 after the DC offset
cancellation has been scheduled.
LINEOUTR_ENA_
DLY
Enables LINEOUTR intermediate
stage
0 = Disabled
1 = Enabled
For normal operation, this bit should
be set to 1 after the output signal path
has been configured, and before DC
offset cancellation is scheduled. This
bit should be set with at least 20us
delay after LINEOUTR_ENA.
LINEOUTR_ENA
Enables LINEOUTR input stage
0 = Disabled
0
0
1 = Enabled
For normal operation, this bit should
be set as the first step of the
LINEOUTR Enable sequence.
Table 41 Headphone / Line Output Pop Suppression Control
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OUTPUT PGA BIAS CONTROL
The output PGA circuits use the Master bias current (see “Reference Voltages and Master Bias”). The
output PGA bias currents can also be controlled using the PGA_BIAS field as described in Table 42.
Selecting a lower bias can be used to reduce power consumption, but may have a marginal impact on
audio performance in some usage modes. Selecting a higher bias offers a performance improvement,
but also an increase in power consumption.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R172 (ACh)
PGA_BIAS [2:0]
Headphone and Lineout PGA bias
control
6:4
000
Analogue
Output Bias 0
000 = Normal bias
001 = Normal bias x 1.5
010 = Normal bias x 0.75
011 = Normal bias x 0.5
100 = Normal bias x 0.33
101 = Normal bias
110 = Normal bias
111 = Normal bias x 2
Table 42 Output PGA Bias Control
OUTPUT DRIVERS BIAS CONTROL
The bias of the Headphone and Lineout drivers can be controlled independently of the PGA bias.
These may be increased or decreased using the OUTPUTS_BIAS field as described in Table 43. This
can be used to reduce power consumption or improve performance.
If it is desired to improve the performance of the outputs with the minimum increase in power
consumption, then it is recommended to increase the OUTPUTS_BIAS level and to use the default
setting of PGA_BIAS.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R187 (BBh)
OUTPUTS_BIAS
[2:0]
Headphone and Lineout Output
Drivers bias control
2:0
000
Analogue
Output Bias 2
000 = Normal bias
001 = Normal bias x 1.5
010 = Normal bias x 0.75
011 = Normal bias x 0.5
100 = Normal bias x 0.33
101 = Normal bias
110 = Normal bias
111 = Normal bias x 2
Table 43 Output Drivers Bias Control
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OUTPUT MIXER CONTROL
Each of the four output mixers has the same four inputs:
DAC Left
DAC Right
Bypass Left
Bypass Right
The input signals to the left and right mixers (feeding HPOUTL/R and LINEOUTL/R) are enabled
using the register fields described in Table 44. These mixers do not provide volume controls on the
inputs or outputs. However, input signals can be attenuated at source using the control fields
LIN_VOL, RIN_VOL, DACL_VOL and DACR_VOL.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R50 (32h)
DACL_TO_MIXO
UTL
Left DAC to Left Output Mixer
Enable
3
1
Analogue Left
Mix 0
0 = disabled
1 = enabled
DACR_TO_MIXO
UTL
Right DAC to Left Output Mixer
Enable
2
1
0
3
2
1
0
0
0
0
0
1
0
0
0 = disabled
1 = enabled
BYPASSL_TO_MI
XOUTL
Left Analogue Input to Left Output
Mixer Enable
0 = disabled
1 = enabled
BYPASSR_TO_M
IXOUTL
Right Analogue Input to Left Output
Mixer Enable
0 = disabled
1 = enabled
R51 (33h)
DACL_TO_MIXO
UTR
Left DAC to Right Output Mixer
Enable
Analogue
Right Mix 0
0 = disabled
1 = enabled
DACR_TO_MIXO
UTR
Right DAC to Right Output Mixer
Enable
0 = disabled
1 = enabled
BYPASSL_TO_MI
XOUTR
Left Analogue Input to Right Output
Mixer Enable
0 = disabled
1 = enabled
BYPASSR_TO_M
IXOUTR
Right Analogue Input to Right
Output Mixer Enable
0 = disabled
1 = enabled
Table 44 Headphone and Line Output Mixer Control
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The input signals to the speaker mixers are enabled and controlled using the register fields described
in Table 45.
These mixers provide a selectable 0dB or -6dB volume control on each input. The input signals may
also be controlled at source using the control fields LIN_VOL, RIN_VOL, DACL_VOL and
DACR_VOL, but it should be noted that adjusting these fields would also affect the other output
mixers.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R52 (34h)
DACL_TO_MIXSP
KL
Left DAC to Left Spkr Mixer Enable
0 = disabled
3
0
Analogue Spk
Mix Left 0
1 = enabled
DACR_TO_MIXS
PKL
Right DAC to Left Spkr Mixer Enable
0 = disabled
2
1
0
0
1 = enabled
BYPASSL_TO_MI
XSPKL
Left Analogue Input to Left Spkr
Mixer Enable
0 = disabled
1 = enabled
BYPASSR_TO_MI
XSPKL
Right Analogue Input to Left Spkr
Mixer Enable
0
3
2
1
0
0
0
0
0
0
0 = disabled
1 = enabled
R53 (35h)
DACL_MIXSPKL_
VOL
Left DAC to Left Spkr Mixer volume
control
Analogue Spk
Mix Left 1
0 = 0dB
1 = -6dB
DACR_MIXSPKL_
VOL
Right DAC to Left Spkr Mixer
volume control
0 = 0dB
1 = -6dB
BYPASSL_MIXSP
KL_VOL
Left Analogue Input to Left Spkr
Mixer volume control
0 = 0dB
1 = -6dB
BYPASSR_MIXSP
KL_VOL
Right Analogue Input to Left Spkr
Mixer volume control
0 = 0dB
1 = -6dB
R54 (36h)
DACL_TO_MIXSP
KR
Left DAC to Right Spkr Mixer Enable
0 = disabled
3
2
0
0
Analogue Spk
Mix Right 0
1 = enabled
DACR_TO_MIXS
PKR
Right DAC to Right Spkr Mixer
Enable
0 = disabled
1 = enabled
BYPASSL_TO_MI
XSPKR
Left Analogue Input to Right Spkr
Mixer Enable
1
0
0
0
0 = disabled
1 = enabled
BYPASSR_TO_MI
XSPKR
Right Analogue Input to Right Spkr
Mixer Enable
0 = disabled
1 = enabled
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R55 (37h)
DACL_MIXSPKR_
VOL
Left DAC to Right Spkr Mixer
volume control
3
0
Analogue Spk
Mix Right 1
0 = 0dB
1 = -6dB
DACR_MIXSPKR
_VOL
Right DAC to Right Spkr Mixer
volume control
2
1
0
0
0
0
0 = 0dB
1 = -6dB
BYPASSL_MIXSP
KR_VOL
Left Analogue Input to Right Spkr
Mixer volume control
0 = 0dB
1 = -6dB
BYPASSR_MIXSP
KR_VOL
Right Analogue Input to Right Spkr
Mixer volume control
0 = 0dB
1 = -6dB
Table 45 Speaker Mixer Control
OUTPUT VOLUME CONTROL
Each analogue output can be independently controlled. The headphone output control fields are
described in Table 46. The line output control fields are described in Table 47. The differential line
output control fields are described in Table 48. The output pins are described in more detail in
“Analogue Outputs”.
The volume and mute status of each output can be controlled individually using the bit fields shown in
Table 46, Table 47 and Table 48.
To prevent “zipper noise” when a volume adjustment is made, a zero-cross function is provided on all
output paths. When this function is enabled, volume updates will not take place until a zero-crossing
is detected. In the event of a long period without zero-crossings, a timeout will apply. The timeout
must be enabled by setting the TO_ENA bit, as defined in “Clocking and Sample Rates”.
The volume update bits control the loading of the output driver volume data. For example, when
HPOUTVU is set to 0, the headphone volume data can be loaded into the respective control register,
but will not actually change the gain setting. The Left and Right headphone volume settings are
updated when a 1 is written to HPOUTVU. This makes it possible to update the gain of a Left/Right
pair of output paths simultaneously.
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R57 (39h)
HPL_MUTE
Left Headphone Output Mute
0 = Un-mute
8
0
Analogue
OUT1 Left
1 = Mute
HPOUTVU
Headphone Output Volume Update
7
0
Writing a 1 to this bit will update
HPOUTL and HPOUTR volumes
simultaneously.
(Write-Only Register)
HPOUTLZC
Left Headphone Output Zero Cross
Enable
6
0
0 = disabled
1 = enabled
HPOUTL_VOL
[5:0]
Left Headphone Output Volume
000000 = -57dB
5:0
10_1101
000001 = -56dB
(… 1dB steps)
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
R58 (3Ah)
HPR_MUTE
HPOUTVU
Right Headphone Output Mute
0 = Un-mute
8
7
0
0
Analogue
OUT1 Right
1 = Mute
Headphone Output Volume Update
Writing a 1 to this bit will update
HPOUTL and HPOUTR volumes
simultaneously.
(Write-Only Register)
HPOUTRZC
Right Headphone Output Zero Cross
Enable
6
0
0 = disabled
1 = enabled
HPOUTR_VOL
[5:0]
Right Headphone Output Volume
000000 = -57dB
000001 = -56dB
(… 1dB steps)
5:0
10_1101
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Table 46 Volume Control for HPOUTL and HPOUTR
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Left Line Output Mute
R59 (3Bh)
LINEOUTL_MUTE
8
0
Analogue
OUT2 Left
0 = Un-mute
1 = Mute
LINEOUTVU
LINEOUTLZC
Line Output Volume Update
7
0
Writing a 1 to this bit will update
LINEOUTL and LINEOUTR volumes
simultaneously.
(Write-Only Register)
Left Line Output Zero Cross Enable
0 = disabled
6
0
1 = enabled
LINEOUTL_VOL
[5:0]
Left Line Output Volume
000000 = -57dB
5:0
11_1001
000001 = -56dB
(… 1dB steps)
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Right Line Output Mute
0 = Un-mute
R60 (3Ch)
LINEOUTR_MUT
E
8
7
0
0
Analogue
OUT2 Right
1 = Mute
LINEOUTVU
Line Output Volume Update
Writing a 1 to this bit will update
LINEOUTL and LINEOUTR volumes
simultaneously.
(Write-Only Register)
LINEOUTRZC
Right Line Output Zero Cross
Enable
6
0
0 = disabled
1 = enabled
LINEOUTR_VOL
[5:0]
Right Line Output Volume
000000 = -57dB
000001 = -56dB
(… 1dB steps)
111001 = 0dB
5:0
11_1001
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Table 47 Volume Control for LINEOUTL and LINEOUTR
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R62 (3Eh)
SPKL_MUTE
Left Speaker Output Mute
0 = Un-mute
8
1
Analogue
OUT3 Left
1 = Mute
SPKVU
Speaker Output Volume Update
7
0
Writing a 1 to this bit will update
LON/LOP and RON/ROP volumes
simultaneously.
(Write-Only Register)
SPKLZC
Left Speaker Output Zero Cross
Enable
6
0
0 = disabled
1 = enabled
SPKL_VOL [5:0]
Left Speaker Output Volume
000000 = -57dB
000001 = -56dB
(… 1dB steps)
5:0
11_1001
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Right Speaker Output Mute
0 = Un-mute
R63 (3Fh)
SPKR_MUTE
SPKVU
8
7
1
0
Analogue
OUT3 Right
1 = Mute
Speaker Output Volume Update
Writing a 1 to this bit will update
LON/LOP and RON/ROP volumes
simultaneously.
(Write-Only Register)
SPKRZC
Right Speaker Output Zero Cross
Enable
6
0
0 = disabled
1 = enabled
SPKR_VOL [5:0]
Right Speaker Output Volume
000000 = -57dB
000001 = -56dB
(… 1dB steps)
5:0
11_1001
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Table 48 Volume Control for LON/LOP and RON/ROP
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ANALOGUE OUTPUTS
The WM8903 has eight analogue output pins:
Headphone outputs, HPOUTL and HPOUTR
Line outputs, LINEOUTL and LINEOUTR
Differential line outputs, LON/LOP and RON/ROP
The output signal paths and associated control registers are illustrated in Figure 33.
HEADPHONE OUTPUTS – HPOUTL AND HPOUTR
The headphone outputs are designed to drive 16Ω or 32Ω headphones. These outputs are ground-
referenced, i.e. no series capacitor is required between the pins and the headphone load. They are
powered by an on-chip charge pump (see “Charge Pump” section). Signal volume at the headphone
outputs is controlled as shown in Table 46.
The ground-referenced outputs incorporates a common mode, or ground loop, feedback path which
provides rejection of system-related ground noise. The return path for the HPOUTL and HPOUTR
outputs is via HPGND. This pin must be connected to ground for normal operation of the headphone
output. No register configuration is required.
LINE OUTPUTS – LINEOUTL AND LINEOUTR
The line outputs are identical to the headphone outputs in design. They are ground-referenced and
power by the on-chip charge pump. Signal volume at the headphone outputs is controlled as shown in
Table 47.
Note that these outputs are intended for driving line loads, as the charge pump powering both the
Headphone and Line outputs can only provide sufficient power to drive one set of headphones at any
given time.
The ground-referenced outputs incorporates a common mode, or ground loop, feedback path which
provides rejection of system-related ground noise. The return path for the LINEOUTL and LINEOUTR
outputs is via LINEGND. This pin must be connected to ground for normal operation of the line output.
No register configuration is required.
DIFFERENTIAL LINE OUTPUTS – LON/LOP AND RON/ROP
The differential line outputs are designed to differential line loads, including external loudspeaker
drivers. The WM9001 is an ideal component for driving loudspeakers from these outputs. These pins
are referenced to VMID (AVDD/2) and are powered directly from the AVDD supply.
Signal volume at the differential line outputs is controlled as shown in Table 48.
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EXTERNAL COMPONENTS FOR GROUND-REFERENCED OUTPUTS
In the case of the ground referenced outputs HPOUTL, HPOUTR, LINEOUTL and LINEOUTR, it is
recommended to connect a zobel network to the audio output pins for best audio performance in all
applications. The components of the zobel network have the effect of dampening high frequency
oscillations or instabilities that can arise outside the audio band under certain conditions. Possible
sources of these instabilities include the inductive load of a headphone coil or an active load in the
form of an external line amplifier. The capacitance of lengthy cables or PCB tracks can also lead to
amplifier instability. The zobel network should comprise a 20 resistor and 100nF capacitor in series
with each other, as illustrated in Figure 34.
Note that the zobel network is recommended for best audio quality and amplifier stability in all cases.
Figure 34 Zobel Network Components for HPOUTL, HPOUTR, LINEOUTL and LINEOUTR
The differential line outputs LOP/LON and ROP/RON would, typically, be connected to differential line
drivers such as the WM9001 speaker driver. In such applications, a zobel network is not required on
these differential line outputs.
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REFERENCE VOLTAGES AND MASTER BIAS
This section describes the analogue reference voltage and bias current controls. It also describes the
VMID soft-start circuit for pop-free start-up and shut-down. Note that, under the recommended usage
conditions of the WM8903, these features will be configured by running the default Start-Up and Shut-
Down sequences as described in the “Control Write Sequencer” section. In these cases, the user
does not need to set these register fields directly.
The analogue circuits in the WM8903 require a mid-rail analogue reference voltage, VMID. This
reference is generated from AVDD via a programmable resistor chain. Together with the external
VMID decoupling capacitor, the programmable resistor chain results in a slow, normal or fast
charging characteristic on VMID. This is controlled by VMID_RES [1:0], and can be used to optimise
the reference for normal operation, low power standby or for fast start-up as described in Table 49.
For normal operation, the VMID_RES field should be set to 01.
The analogue circuits in the WM8903 require a bias current. The normal bias current is enabled by
setting BIAS_ENA. Note that the normal bias current source requires VMID to be enabled also. The
normal bias current can also be controlled using the ISEL field as described in Table 49. This can be
used to reduce power consumption, but may have a detrimental impact on audio performance in
some usage modes. The default setting is recommended.
Note that the DAC and Output PGA bias circuits may also be adjusted in order to reduce power
consumption. For details, see “Digital-to-Analogue Converter (DAC)“ or “Output Signal Path”.
An alternate bias current source (Start-Up Bias) is provided for pop-free start-up; this is selected
using POBCTRL (see Table 50). Note that the default setting of POBCTRL selects the Start-Up Bias.
The normal bias is only selected when POBCTRL is set to logic 0.
REGISTER
ADDRESS
BIT
LABEL
ISEL [1:0]
DEFAULT
DESCRIPTION
R4 (04h)
Master Bias control
3:2
10
Bias Control
0
00 = Normal bias x 0.5
01 = Normal bias x 0.75
10 = Normal bias
11 = Normal bias x 1.5
BIAS_ENA
Enables the Normal bias current
0
0
generator (for all analogue functions)
0 = Disabled
1 = Enabled
R5 (05h)
VMID_RES [1:0]
VMID Divider Enable and Select
00 = VMID disabled (for OFF mode)
2:1
00
VMID
Control 0
01 = 2 x 50k divider (for normal
operation)
10 = 2 x 250k divider (for low power
standby)
11 = 2 x 5k divider (for fast start-up)
Table 49 Reference Voltages and Master Bias Enable
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A pop-suppressed start-up requires VMID to be enabled smoothly, without the step change normally
associated with the initial stage of the VMID capacitor charging. A pop-suppressed start-up also
requires the analogue bias current to be enabled throughout the signal path prior to the VMID
reference voltage being applied. The WM8903 incorporates pop-suppression circuits which address
these requirements.
The alternate current source (Start-Up Bias) is enabled by STARTUP_BIAS_ENA. The start-up bias
is selected (in place of the normal bias) by POBCTRL. It is recommended that the start-up bias is
used during start-up, before switching back to the higher quality, normal bias.
VMID_IO_ENA has the same functionality as STARTUP_BIAS_ENA. The start-up bias is enabled by
setting either of these bits.
A soft-start circuit is provided in order to control the switch-on of the VMID reference. The soft-start
control circuit is enabled by setting VMID_SOFT. Three slew rates are provided, under control of the
VMID_SOFT field. When the soft-start circuit is enabled prior to enabling VMID_RES, the reference
voltage rises smoothly, without the step change that would otherwise occur. It is recommended that
the soft-start circuit and the output signal path be enabled before VMID is enabled by VMID_RES.
A soft shut-down is provided, using the soft-start control circuit and the start-up bias current
generator. The soft shut-down of VMID is achieved by setting VMID_SOFT, STARTUP_BIAS_ENA
and POBCTRL to select the start-up bias current and soft-start circuit prior to setting VMID_RES=00.
REGISTER
ADDRESS
BIT
LABEL
POBCTRL
DEFAULT
DESCRIPTION
R4 (04h)
Selects the bias current source
0 = Normal bias
4
1
Bias Control
0
1 = Start-Up bias
STARTUP_BIAS_
ENA
Enables the Start-Up bias current
generator
1
5
0
0
0 = Disabled
1 = Enabled
R5 (05h)
VMID_IO_ENA
Enables the Start-Up bias current
generator
VMID
Control 0
0 = Disabled
1 = Enabled
(same functionality as
STARTUP_BIAS_ENA)
VMID_SOFT [1:0]
VMID soft start enable / slew rate
control
4:3
10
00 = Disabled
01 = Fast soft start
10 = Nominal soft start
11 = Slow soft start
Table 50 Soft Start Control
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POP SUPPRESSION CONTROL
The WM8903 incorporates Wolfson’s SilentSwitch™ technology which enables pops normally
associated with Start-Up, Shut-Down or signal path control to be suppressed. To achieve maximum
benefit from these features, careful attention is required to the sequence and timing of these controls.
Note that, under the recommended usage conditions of the WM8903, these features will be
configured by running the default Start-Up and Shut-Down sequences as described in the “Control
Write Sequencer” section. In these cases, the user does not need to set these register fields directly.
The Pop Suppression controls relating to the Headphone / Line Output drivers are described in the
“Output Signal Path” section.
DISABLED INPUT / OUTPUT CONTROL
The analogue inputs to the WM8903 and the Differential Line (Speaker) outputs are biased to VMID
in normal operation. In order to avoid audible pops caused by a disabled signal path dropping to
AGND, the WM8903 can maintain these connections at VMID when the relevant input or output stage
is disabled. This is achieved by connecting a buffered VMID reference to the input or output. The
buffered VMID reference is enabled by setting VMID_BUF_ENA.
When the buffered VMID reference is enabled, it is connected to any unused input pins by setting the
BUFIO_ENA register bit. When buffered VMID is enabled, it is connected to any disabled Differential
Line outputs (speaker driver outputs) by setting VMID_TIE_ENA. The resistance associated with
VMID_TIE_ENA can be either 500 or 20k, depending on the VROI register bit.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R5 (05h)
VMID_TIE_ENA
VMID buffer to Differential Lineouts
0 = Disabled
7
0
VMID
Control 0
1 = Enabled
(only applies when relevant outputs
are disabled, ie. SPLK=0 or SPKR=0.
Resistance is controlled by VROI.)
BUFIO_ENA
VMID_BUF_ENA
VROI
VMID buffer to unused Inputs/Outputs
0 = Disabled
6
0
0
0
0
0
1 = Enabled
VMID Buffer Enable
0 = Disabled
1 = Enabled
R65 (41h)
Select VMID_TIE_ENA resistance for
disabled Differential Lineouts
0 = 20k ohm
1 = 500 ohm
Table 51 Disabled Input / Output Control
DIFFERENTIAL LINE OUTPUT DISCHARGE CONTROL
The differential line output paths can be actively discharged to AGND through internal resistors if
desired. This is desirable at start-up in order to achieve a known output stage condition prior to
enabling the soft-start VMID reference voltage. This is also desirable in shut-down to prevent the
external connections from being affected by the internal circuits. The Differential Line outputs
(speaker driver outputs) can be discharged to AGND by setting SPK_DISCHARGE.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R65 (41h)
SPK_DISCHARG
E
Speaker Discharge Enable
0 = Disabled
1
0
1 = Enable
Table 52 Differential Line Output Discharge Control
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CHARGE PUMP
The WM8903 incorporates a dual-mode Charge Pump which generates the supply rails for the
headphone and line output drivers, HPOUTL, HPOUTR, and LINEOUTL and LINEOUTR. The Charge
Pump has a single supply input, CPVDD, and generates split rails VPOS and VNEG according to the
selected mode of operation. The Charge Pump connections are illustrated in Figure 35 (see the
“Electrical Characteristics” section for external component values). An input decoupling capacitor may
also be required at CPVDD, depending upon the system configuration.
Figure 35 Charge Pump External Connections
The Charge Pump is enabled by setting the CP_ENA bit. When enabled, the charge pump adjusts the
output voltages (VPOS and VNEG) as well as the switching frequency in order to optimise the power
consumption according to the operating conditions. This can take two forms, which are selected using
the CP_DYN_PWR register bit.
Register control (CP_DYN_PWR = 0)
Dynamic control (CP_DYN_PWR = 1)
Under Register control, the HPOUTL_VOL, HPOUTR_VOL, LINEOUTL_VOL and LINEOUTR_VOL
register settings are used to control the charge pump mode of operation.
Under Dynamic control, the audio signal level in the DAC is used to control the charge pump mode of
operation. This is the Wolfson ‘Class W’ mode, which allows the power consumption to be optimised
in real time, but can only be used if the DAC is the only signal source. This mode should not be used
if any of the bypass paths are used to mix analogue inputs into the output signal path.
Under the recommended usage conditions of the WM8903, the Charge Pump will be enabled by
running the default Start-Up sequence as described in the “Control Write Sequencer” section.
(Similarly, it will be disabled by running the Shut-Down sequence.) In these cases, the user does not
need to write to the CP_ENA bit. The Charge Pump operating mode defaults to Register control;
Dynamic control may be selected by setting the CP_DYN_PWR register bit, if appropriate.
When digital sidetone is used (see “Digital Mixing”), it is recommended that the Charge Pump
operates in Register Control mode only (CP_DYN_PWR = 0). This is because the Dynamic Control
mode (Class W) does not measure the sidetone signal level and hence the Charge Pump
configuration cannot be optimised for all signal conditions when digital sidetone is enabled; this could
lead to signal clipping.
The MCLK signal must be present for the charge pump to function. The clock division from MCLK is
handled transparently by the WM8903 without user intervention, as long as MCLK and sample rates
are set correctly (see “Clocking and Sample Rates” section). The clock divider ratio depends on the
SAMPLE_RATE [3:0], CLK_SYS_MODE [1:0], and CLK_SYS_RATE [3:0] register settings.
The charge pump requires a minimum CLK_SYS frequency of 2.8224MHz.
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The Charge Pump control fields are described in Table 53.
REGISTER
ADDRESS
BIT
LABEL
CP_ENA
DEFAULT
DESCRIPTION
R98 (62h)
Enable charge-pump digits
0 = disable
0
0
Charge Pump
0
1 = enable
R104 (68h)
Class W 0
CP_DYN_PWR
Enable dynamic charge pump power
control
0
0
0 = charge pump controlled by
volume register settings
1 = charge pump controlled by real-
time audio level
Table 53 Charge Pump Control
DC SERVO
The WM8903 provides a DC servo circuit on the headphone and line outputs in order to remove DC
offset from these ground-referenced outputs. When enabled, the DC servo ensures that the DC level
of these outputs remains within 1.5mV of ground. Removal of the DC offset is important because any
deviation from GND at the output pin will cause current to flow through the load under quiescent
conditions, resulting in increased power consumption. Additionally, the presence of DC offsets can
result in audible pops and clicks at power up and power down.
The recommended usage of the DC Servo is initialised by running the default Start-Up sequence as
described in the “Control Write Sequencer” section. The default Start-Up sequence selects
START_STOP servo mode, which causes a one-off correction to be performed, after which the
measured DC offset is then maintained on the headphone and line outputs.
If a different usage is required, e.g. if one or more of the outputs is not in use, or if periodic DC offset
correction is required, then the default Start-Up sequence may be modified according to specific
requirements. The relevant control fields are defined in Table 54 .
If DC offset correction is not required on any output, then DCS_MASTER_ENA should be set to 0.
Setting this field to 0 before running the Start-Up sequence will disable the DC Servo on all outputs.
If DC offset correction is only required on selected channels, then DCS_ENA should be set
accordingly. Setting this field to 1111b enables the DC Servo on all outputs. Setting any bit to 0
disables the DC Servo on the corresponding output. Disabling the DC Servo on unused outputs
reduces power consumption in the device. To modify this within the Start-Up sequence, the data in
WSEQ Address 23 and WSEQ Address 24 should be updated (see “Control Write Sequencer”)
before running the sequence.
If periodic updates to the DC offset correction is required, then DCS_MODE should be modified.
Setting this field to 11b selects START_UPDATE servo mode, which causes the DC offset to be
measured and corrected on a periodic basis. The default time between updates is approximately 10
minutes. Scheduling periodic updates enables the WM8903 to compensate for any change in DC
offsets which might have occurred due to power supply drift or other factors. To modify this within the
Start-Up sequence, the data in WSEQ Address 22 should be updated (see “Control Write
Sequencer”) before running the sequence.
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
R67 (43h)
DCS_MASTER_ENA
DC Servo Master Control
0 = DC Servo Reset
1 = DC Servo Enabled
DC Servo Enable
4
1
DC Servo 0
DCS_ENA [3:0]
3:0
1:0
0000
[3] - HPOUTL enable
[2] - HPOUTR enable
[1] - LOUTL enable
[0] - LOUTR enable
DC Servo Mode
R69 (45h)
DCS_MODE [1:0]
00
DC Servo 2
00 = WRITE_STOP
01 = WRITE_UPDATE
10 = START_STOP
11 = START_UPDATE
Table 54 DC Servo Control
To reduce power consumption when unused audio outputs are disabled, the DC Servo correction
should also be disabled. The WM8903 provides the capability to quickly resume the necessary DC
Servo correction when the outputs are re-enabled, without the time delay associated with the
START_STOP mode of DC Servo operation.
If the DC Servo correction is disabled using the DCS_ENA bits, but the DCS_MASTER_ENA bit is
maintained at 1, then the DC Servo will retain the latest correction values in its memory. These values
will be re-applied when the DC Servo is later enabled via the DCS_ENA bits.
An alternative method to apply known correction settings is to read the correction values from the
WM8903 register map and to store these for later use. After DC offset correction has been performed,
the applicable correction values can be read from the fields in the Servo Readback registers R81 to
R84 described in Table 55.
Setting DCS_MODE to 00b or 01b selects WRITE_STOP mode and WRITE_UPDATE mode
respectively. WRITE_STOP mode is similar to START_STOP mode, except that the DC Servo
correction factors are read from internal registers, instead of being calculated from the measured
output conditions. In the same way, WRITE_UPDATE mode is similar to START_UPDATE mode.
When the DC Servo is commanded to one of these modes, the initial DC offset correction values are
read from the _WRITE_VAL field in registers R71 to R74 described in Table 55.
Selecting WRITE_STOP or WRITE_UPDATE mode applies initial settings which should be written to
registers R71 to R74 before the DC Servo is enabled. In WRITE_STOP mode, no further DC
correction is applied. In WRITE_UPDATE mode, the DC Servo will periodically measure and adjust
the DC offset correction. Similar to START_UPDATE mode, the default time between updates is
approximately 10 minutes.
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R71 (47h)
DC Servo 4
DCS_HPOUTL_WRITE_VAL
[7:0]
Value to send to Left
Headphone Output Servo
in a WRITE mode
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
R72 (48h)
DC Servo 5
DCS_HPOUTR_WRITE_VAL
[7:0]
Value to send to Right
Headphone Output Servo
in a WRITE mode
7:0
7:0
7:0
7:0
0000_0000
0000_0000
0000_0000
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
R73 (49h)
DC Servo 6
DCS_LOUTL_WRITE_VAL
[7:0]
Value to send to Left Line
Output Servo in a WRITE
mode
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
R74 (4Ah)
DC Servo 7
DCS_LOUTR_WRITE_VAL
[7:0]
Value to send to Right Line
Output Servo in a WRITE
mode
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
R81 (51h)
DC Servo
Readback 1
DCS_HPOUTL_INTEG [7:0]
DCS_HPOUTR_INTEG [7:0]
Readback value on Left
Headphone Output Servo.
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
(Read-Only Register)
R82 (52h)
DC Servo
Readback 2
Readback value on
Headphone Right Output
Servo.
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
(Read-Only Register)
R83 (53h)
DC Servo
Readback 3
DCS_LOUTL_INTEG [7:0]
DCS_LOUTR_INTEG [7:0]
Readback value on Left
Line Output Servo.
7:0
7:0
0000_0000
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
(Read-Only Register)
R84 (54h)
DC Servo
Readback 4
Readback value on Right
Line Output Servo.
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
(Read-Only Register)
Table 55 DC Servo Initial Settings and Readback
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DIGITAL AUDIO INTERFACE
The digital audio interface is used for inputting DAC data into the WM8903 and outputting ADC data
from it. The digital audio interface uses four pins:
ADCDAT: ADC data output
DACDAT: DAC data input
LRC: DAC and ADC data alignment clock
BCLK: Bit clock, for synchronisation
The clock signals BCLK and LRCLK can be outputs when the WM8903 operates as a master, or
inputs when it is a slave (see “Master And Slave Mode Operation” below).
Note that the BCLK pin can also support other functions, as described under “General Purpose
Input/Output (GPIO)”. BCLK is the default function on this pin (GP5_FN = 1h). Under default
conditions, the other GPIO control fields for this pin have no effect.
Four different audio data formats are supported:
Left justified
Right justified
I2S
DSP mode
All four of these modes are MSB first. They are described in “Audio Data Formats (Normal Mode)”
below. Refer to the “Signal Timing Requirements” section for timing information.
Time Division Multiplexing (TDM) is available in all four data format modes. The WM8903 can be
programmed to send and receive data in one of two time slots.
PCM operation is supported using the DSP mode.
MASTER AND SLAVE MODE OPERATION
The WM8903 digital audio interface can operate in master or slave mode, as shown in Figure 36 and
Figure 37.
Figure 36 Master Mode
Figure 37 Slave Mode
In master mode, BCLK is derived from CLK_SYS via a programmable division set by BCLK_DIV.
In master mode, LRC is derived from BCLK via a programmable division set by LRCLK_RATE. The
BCLK input to this divider may be internal or external, allowing mixed master and slave modes.
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The direction of these signals and the clock frequencies are controlled as described in the “Digital
Audio Interface Control” section.
BCLK and LRC can be enabled as outputs in Slave mode, allowing mixed Master/Slave operation -
see “Digital Audio Interface Control”.
OPERATION WITH TDM
Time division multiplexing (TDM) allows multiple devices to transfer data simultaneously on the same
bus. The WM8903 ADCs and DACs support TDM in master and slave modes for all data formats and
word lengths. TDM is enabled and configured using register bits defined in the “Digital Audio Interface
Control” section.
BCLK
LRC
BCLK
LRC
WM8903
Processor
WM8903
Processor
ADCDAT
DACDAT
ADCDAT
DACDAT
BCLK
LRC
BCLK
LRC
WM8903 or
Similar
WM8903 or
Similar
ADCDAT
DACDAT
ADCDAT
DACDAT
CODEC
CODEC
Figure 38 TDM with WM8903 as Master
Figure 39 TDM with Other CODEC as Master
BCLK
LRC
WM8903
Processor
ADCDAT
DACDAT
BCLK
LRC
WM8903 or
Similar
ADCDAT
DACDAT
CODEC
Figure 40 TDM with Processor as Master
Note: The WM8903 is a 24-bit device. If the user operates the WM8903 in 32-bit mode then the 8
LSBs will be ignored on the receiving side and not driven on the transmitting side. It is therefore
recommended to add a pull-down resistor if necessary to the DACDAT line and the ADCDAT line in
TDM mode.
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BCLK FREQUENCY
The BCLK frequency is controlled relative to CLK_SYS by the BCLK_DIV divider. Internal clock divide
and phase control mechanisms ensure that the BCLK and LRC edges will occur in a predictable and
repeatable position relative to each other and relative to the data for a given combination of
DAC/ADC sample rate and BCLK_DIV settings.
BCLK_DIV is defined in the “Digital Audio Interface Control” section. See also the “Clocking and
Sample Rates” section for more information.
AUDIO DATA FORMATS (NORMAL MODE)
In Right Justified mode, the LSB is available on the last rising edge of BCLK before a LRC transition.
All other bits are transmitted before (MSB first). Depending on word length, BCLK frequency and
sample rate, there may be unused BCLK cycles after each LRC transition.
Figure 41 Right Justified Audio Interface (assuming n-bit word length)
In Left Justified mode, the MSB is available on the first rising edge of BCLK following a LRC
transition. The other bits up to the LSB are then transmitted in order. Depending on word length,
BCLK frequency and sample rate, there may be unused BCLK cycles before each LRC transition.
Figure 42 Left Justified Audio Interface (assuming n-bit word length)
In I2S mode, the MSB is available on the second rising edge of BCLK following a LRC transition. The
other bits up to the LSB are then transmitted in order. Depending on word length, BCLK frequency
and sample rate, there may be unused BCLK cycles between the LSB of one sample and the MSB of
the next.
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Figure 43 I2S Justified Audio Interface (assuming n-bit word length)
In DSP mode, the left channel MSB is available on either the 1st (mode B) or 2nd (mode A) rising edge
of BCLK (selectable by AIF_LRCLK_INV) following a rising edge of LRC. Right channel data
immediately follows left channel data. Depending on word length, BCLK frequency and sample rate,
there may be unused BCLK cycles between the LSB of the right channel data and the next sample.
In device master mode, the LRC output will resemble the frame pulse shown in Figure 44 and Figure
45. In device slave mode, Figure 46 and Figure 47, it is possible to use any length of frame pulse less
than 1/fs, providing the falling edge of the frame pulse occurs greater than one BCLK period before
the rising edge of the next frame pulse.
Figure 44 DSP Mode Audio Interface (mode A, AIF_LRCLK_INV=0, Master)
Figure 45 DSP Mode Audio Interface (mode B, AIF_LRCLK_INV=1, Master)
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Figure 46 DSP Mode Audio Interface (mode A, AIF_LRCLK_INV=0, Slave)
Figure 47 DSP Mode Audio Interface (mode B, AIF_LRCLK_INV=1, Slave)
PCM operation is supported in DSP interface mode. WM8903 ADC data that is output on the Left
Channel will be read as mono PCM data by the receiving equipment. Mono PCM data received by the
WM8903 will be treated as Left Channel data. This data may be routed to the Left/Right DACs as
described in the “Digital Mixing” section.
AUDIO DATA FORMATS (TDM MODE)
TDM is supported in master and slave mode and is enabled by register bits AIFADC_TDM and
AIFDAC_TDM. All audio interface data formats support time division multiplexing (TDM) for ADC and
DAC data.
Two time slots are available (Slot 0 and Slot 1), selected by register bits AIFADC_TDM_CHAN and
AIFDAC_TDM_CHAN which control time slots for the ADC data and the DAC data.
When TDM is enabled, the ADCDAT pin will be tri-stated immediately before and immediately after
data transmission, to allow another audio device to drive this signal line for the remainder of the
sample period. It is important that two audio devices do not attempt to drive the data pin
simultaneously, as this could result in a short circuit. See “Audio Interface Timing” for details of the
ADCDAT output relative to BCLK signal. Note that it is possible to ensure a gap exists between
transmissions by setting the transmitted word length to a value higher than the actual length of the
data. For example, if 32-bit word length is selected where only 24-bit data is available, then the
WM8903 interface will tri-state after transmission of the 24-bit data; this creates an 8-bit gap after the
WM8903’s TDM transmission slot.
When TDM is enabled, BCLK frequency must be high enough to allow data from both time slots to be
transferred. The relative timing of Slot 0 and Slot 1 depends upon the selected data format as shown
in Figure 48 to Figure 52.
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Figure 48 TDM in Right-Justified Mode
Figure 49 TDM in Left-Justified Mode
Figure 50 TDM in I2S Mode
Figure 51 TDM in DSP Mode A
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Figure 52 TDM in DSP Mode B
DIGITAL AUDIO INTERFACE CONTROL
The register bits controlling audio data format, word length left/right channel data source and TDM are
summarised in Table 56.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R24 (18h)
DACL_DATINV
Left DAC Invert
12
0
Audio
Interface 0
0 = Left DAC output not inverted
1 = Left DAC output inverted
Right DAC Invert
DACR_DATINV
AIFADCL_SRC
11
7
0
0
0 = Right DAC output not inverted
1 = Right DAC output inverted
Left Digital Audio channel source
0 = Left ADC data is output on left
channel
1 = Right ADC data is output on left
channel
AIFADCR_SRC
AIFDACL_SRC
AIFDACR_SRC
AIFDAC_TDM
Right Digital Audio channel source
6
5
4
1
0
1
0 = Left ADC data is output on right
channel
1 = Right ADC data is output on
right channel
Left DAC Data Source Select
0 = Left DAC outputs left channel
data
1 = Left DAC outputs right channel
data
Right DAC Data Source Select
0 = Right DAC outputs left channel
data
1 = Right DAC outputs right channel
data
R25 (19h)
DAC TDM Enable
13
12
11
0
0
0
Audio
Interface 1
0 = Normal DACDAT operation
1 = TDM enabled on DACDAT
DACDAT TDM Channel Select
0 = DACDAT data input on slot 0
1 = DACDAT data input on slot 1
ADC TDM Enable
AIFDAC_TDM_C
HAN
AIFADC_TDM
0 = Normal ADCDAT operation
1 = TDM enabled on ADCDAT
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
AIFADC_TDM_C
HAN
ADCDAT TDM Channel Select
0 = ADCDAT outputs data on slot 0
1 = ADCDAT output data on slot 1
BCLK Invert
10
0
AIF_BCLK_INV
AIF_LRCLK_INV
7
4
0
0
0 = BCLK not inverted
1 = BCLK inverted
LRC Polarity / DSP Mode A-B
select.
Right, left and I2S modes – LRC
polarity
0 = Not Inverted
1 = Inverted
DSP Mode – Mode A-B select
0 = MSB is available on 2nd BCLK
rising edge after LRC rising edge
(mode A)
1 = MSB is available on 1st BCLK
rising edge after LRC rising edge
(mode B)
AIF_WL [1:0]
AIF_FMT [1:0]
Digital Audio Interface Word Length
00 = 16 bits
3:2
1:0
00
10
01 = 20 bits
10 = 24 bits
11 = 32 bits
Digital Audio Interface Format
00 = Right Justified
01 = Left Justified
10 = I2S
11 = DSP
R38 (26h)
ADCL_DATINV
ADCR_DATINV
Left ADC Invert
1
0
0
0
ADC Digital 0
0 = Left ADC output not inverted
1 = Left ADC output inverted
Right ADC Invert
0 = Right ADC output not inverted
1 = Right ADC output inverted
Table 56 Digital Audio Interface Data Control
Note that the WM8903 is a 24-bit device. In 32-bit mode (AIF_WL=11), the 8 LSBs are ignored on the
receiving side and not driven on the transmitting side.
BCLK AND LRCLK CONTROL
The audio interface can be programmed to operate in master mode or slave mode using the
BCLK_DIR and LRCLK_DIR register bits. In master mode, the BCLK and LRCLK signals are
generated by the WM8903 when any of the ADCs or DACs is enabled. In slave mode, the BCLK and
LRCLK clock outputs are disabled by default to allow another digital audio interface to drive these
pins.
It is also possible to force the BCLK or LRCLK signals to be output using BCLK_DIR and
LRCLK_DIR, allowing mixed master and slave modes. The BCLK_DIR and LRCLK_DIR fields are
defined in Table 57.
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When BCLK is not selected (GP5_FN ≠ 1), the WM8903 uses the MCLK input as the Bit Clock,
provided that BCLK_DIR is set to 0 to configure BCLK as an input, ie. BCLK slave mode. This
configuration can offer power consumption benefits in addition to flexibility of GPIO functionality,
When the BCLK pin is an output (BCLK_DIR=1), BCLK is derived from the internal CLK_SYS signal
(see “Clocking and Sample Rates”). In this case, the BCLK frequency is controlled in relation to
CLK_SYS by the BCLK_DIV register field. When BCLK is an input, BCLK_DIV has no effect.
When the LRC pin is an output (LRCLK_DIR=1), LRC is derived from BCLK (irrespective of whether
BCLK is an input or output). In this case, the LRC frequency is controlled in relation to BCLK by the
LRCLK_RATE register field. When LRC is an input, LRCLK_RATE has no effect.
BCLK_DIV and LRCLK_RATE are defined in Table 57. The clocking scheme is illustrated in the
“Clocking and Sample Rates” section - see Figure 55.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R25 (19h)
LRCLK_DIR
Audio Interface LRC Direction
0 = LRC is input
9
0
Audio Interface
1
1 = LRC is output
BCLK_DIR
Audio Interface BCLK Direction
0 = BCLK is input
6
0
1 = BCLK is output
R26 (1Ah)
BCLK_DIV [4:0]
BCLK Frequency (Master Mode)
00000 = CLK_SYS
4:0
0_1000
Audio Interface
2
00001 = Reserved
00010 = CLK_SYS / 2
00011 = CLK_SYS / 3
00100 = CLK_SYS / 4
00101 = CLK_SYS / 5
00110 = Reserved
00111 = CLK_SYS / 6
01000 = CLK_SYS / 8 (default)
01001 = CLK_SYS / 10
01010 = Reserved
01011 = CLK_SYS / 12
01100 = CLK_SYS / 16
01101 = CLK_SYS / 20
01110 = CLK_SYS / 22
01111 = CLK_SYS / 24
10000 = Reserved
10001 = CLK_SYS / 30
10010 = CLK_SYS / 32
10011 = CLK_SYS / 44
10100 = CLK_SYS / 48
LRC Rate (Master Mode)
R27 (1Bh)
LRCLK_RATE
[10:0]
10:0
000_0010
_0010
Audio Interface
3
LRC clock output = BCLK /
LRCLK_RATE
Integer (LSB = 1)
Valid range: 8 to 2047
50:50 LRCLK duty cycle is only
guaranteed with even values (8, 10,
… 2046).
Table 57 Digital Audio Interface Clock Control
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COMPANDING
The WM8903 supports A-law and -law companding on both transmit (ADC) and receive (DAC) sides
as shown in Table 58.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R24 (18h)
ADC_COMP
ADC Companding Enable
0 = disabled
3
0
Audio
Interface 0
1 = enabled
ADC_COMPMO
DE
ADC Companding Type
0 = µ-law
2
1
0
0
0
0
1 = A-law
DAC_COMP
DAC Companding Enable
0 = disabled
1 = enabled
DAC_COMPMO
DE
DAC Companding Type
0 = µ-law
1 = A-law
Table 58 Companding Control
Companding uses a piecewise linear approximation of the following equations (as set out by ITU-T
G.711 standard) for data compression:
-law (where =255 for the U.S. and Japan):
F(x) = ln( 1 + |x|) / ln( 1 + )
A-law (where A=87.6 for Europe):
F(x) = A|x| / ( 1 + lnA)
-1 ≤ x ≤ 1
x ≤ 1/A
F(x) = ( 1 + lnA|x|) / (1 + lnA)
1/A ≤ x ≤ 1
The companded data is also inverted as recommended by the G.711 standard (all 8 bits are inverted
for -law, all even data bits are inverted for A-law). The data will be transmitted as the first 8 MSBs of
data.
Companding converts 13 bits (-law) or 12 bits (A-law) to 8 bits using non-linear quantization. This
provides greater precision for low amplitude signals than for high amplitude signals, resulting in a
greater usable dynamic range than 8 bit linear quantization. The companded signal is an 8-bit word
comprising sign (1 bit), exponent (3 bits) and mantissa (4 bits).
8-bit mode is selected whenever DAC_COMP=1 or ADC_COMP=1. The use of 8-bit data allows
samples to be passed using as few as 8 BCLK cycles per LRC frame. When using DSP mode B, 8-bit
data words may be transferred consecutively every 8 BCLK cycles.
8-bit mode (without Companding) may be enabled by setting DAC_COMPMODE=1 or
ADC_COMPMODE=1, when DAC_COMP=0 and ADC_COMP=0.
BIT7
BIT [6:4]
BIT [3:0]
SIGN
EXPONENT
MANTISSA
Table 59 8-bit Companded Word Composition
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u-law Companding
1
120
100
80
60
40
20
0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Normalised Input
Figure 53 µ-Law Companding
A-law Companding
1
120
100
80
60
40
20
0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
Normalised Input
Figure 54 A-Law Companding
LOOPBACK
Setting the LOOPBACK register bit enables digital loopback. When this bit is set, the ADC digital data
output is routed to the DAC digital data input path. The digital audio interface input (DACDAT) is not
used when LOOPBACK is enabled.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R24 (18h)
LOOPBACK
Digital Loopback Function
0 = No loopback
8
0
Audio
Interface 0
1 = Loopback enabled (ADC data
output is directly input to DAC data
input)
Table 60 Loopback Control
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Note: When the digital sidetone is enabled, ADC data will continue to be added to DAC data when
loopback is enabled.
CLOCKING AND SAMPLE RATES
The WM8903 supports a wide range of standard audio sample rates from 8kHz to 96kHz. When the
DAC and ADC are both enabled, they operate at the same sample rate, fs. Oversample rates of 64fs
or 128fs are supported (based on a 48kHz sample rate).
Note that simultaneous ADC and DAC operation at 88.2kHz or 96kHz is not possible. Digital
microphone operation is not supported at 88.2kHz or 96kHz sample rates. The clocking options for
88.2kHz or 96kHz ADC operation are restricted to specific configurations only, as detailed in this
section.
The internal clocks for the WM8903 are all derived from a common internal clock source, CLK_SYS.
This clock is the reference for the ADCs, DACs, DSP core functions, digital audio interface, DC servo
control and other internal functions.
CLK_SYS can either be derived directly from MCLK, or may be generated from a Frequency Locked
Loop (FLL) using MCLK, BCLK or LRC as a reference. Many commonly-used audio sample rates can
be derived directly from typical MCLK frequencies; the FLL provides additional flexibility for a wide
range of MCLK frequencies. To avoid audible glitches, all clock configurations must be set up before
enabling playback. The FLL can be used to generate a free-running clock in the absence of an
external reference source; see “Frequency Locked Loop (FLL)” for further details.
The WM8903 supports automatic clocking configuration. The programmable dividers associated with
the ADCs, DACs, DSP core functions and DC servo are configured automatically, with values
determined from the SAMPLE_RATE, CLK_SYS_RATE and CLK_SYS_MODE fields. Note that the
user must also configure the Digital Audio Interface.
A 256kHz clock, supporting the Control Write Sequencer, MICBIAS Current Detect filtering and a
number of internal functions, is derived from CLK_SYS. This clock is enabled by WSMD_CLK_ENA.
A slow clock, TOCLK, is used to de-bounce the button/accessory detect inputs, and to set the timeout
period for volume updates when zero-cross detect is used. This clock is enabled by TO_ENA.
The Charge Pump and DC servo control functions are clocked from CLK_SYS.
In master mode, BCLK is derived from CLK_SYS via a programmable divider set by BCLK_DIV. In
master mode, the LRC is derived from BCLK via a programmable divider LRCLK_RATE. The LRC
can be derived from an internal or external BCLK source, allowing mixed master/slave operation.
The overall clocking scheme for the WM8903 is illustrated in Figure 55. Note that BCLK and LRC are
described in the “Digital Audio Interface” section.
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Figure 55 Clocking Overview
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CLK_SYS CONTROL
The CLK_SRC_SEL bit is used to select the source for CLK_SYS. The source may be either the
MCLK input or the FLL output. The selected source may be adjusted by the MCLKDIV2 divider to
generate CLK_SYS. These register fields are described in Table 61. See “Frequency Locked Loop
(FLL)” for more details of the Frequency Locked Loop clock generator.
The CLK_SYS signal is enabled by register bit CLK_SYS_ENA. This bit should be set to 1 for normal
operation with MCLK applied. This bit should be set to 0 when reconfiguring clock sources. It is not
recommended to change CLK_SRC_SEL while the CLK_SYS_ENA bit is set.
The following operating frequency limits must be observed when configuring CLK_SYS. Failure to
observe these limits will result in degraded noise performance and/or incorrect ADC/DAC
functionality.
.
.
If DAC_OSR = 0 then CLK_SYS 3MHz
If DAC_OSR = 1 then CLK_SYS 6MHz
For DAC operation up to 48kHz sample rate, the following CLK_SYS limits are applicable. These
conditions are applicable whenever DACL_ENA = 1 or DACR_ENA = 1.
Note that the ADC operation limits must also be observed if either ADC is enabled. See “Digital-to-
Analogue Converter (DAC)” for definitions of DAC_MONO and DAC_OSR.
.
.
.
.
If DAC_MONO = 0 and DAC_OSR = 0, then CLK_SYS 128 x fs
If DAC_MONO = 0 and DAC_OSR = 1, then CLK_SYS 256 x fs
If DAC_MONO = 1 and DAC_OSR = 0, then CLK_SYS 64 x fs
If DAC_MONO = 1 and DAC_OSR = 1, then CLK_SYS 128 x fs
For ADC operation up to 48kHz sample rate, the following CLK_SYS limits are applicable. These
conditions are applicable whenever ADCL_ENA = 1 or ADCR_ENA = 1.
Note that the DAC operation limits must also be observed if either DAC is enabled. See “Analogue-to-
Digital Converter (ADC)” for the definition of ADC_OSR.
.
.
If ADC_OSR = 0, then CLK_SYS 128 x fs
If ADC_OSR = 1, then CLK_SYS 256 x fs
Further requirements for 88.2kHz and 96kHz operation are provided later in this section. Note that
simultaneous ADC and DAC operation at 88.2kHz or 96kHz is not possible.
The clocking of the ADC and DAC circuits is derived from CLK_DSP, which is enabled by
CLK_DSP_ENA. (Note that CLK_SYS must also be enabled.)
A 256kHz clock required for the Control Write Sequencer and MICBIAS Current Detect filtering is
derived from CLK_SYS. The 256kHz clock is enabled by WSMD_CLK_ENA.
The slow clock (TOCLK) required for input signal de-bouncing and volume update timeout functions is
derived from the 256kHz clock. The TOCLK clock is enabled by TO_ENA.
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The CLK_SYS control register fields are defined in Table 61.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R20 (14h)
MCLKDIV2
Enables divide by 2 on MCLK
0 = CLK_SYS = MCLK
1 = CLK_SYS = MCLK / 2
SYSCLK Source Select
0 = MCLK
0
0
Clock Rates 0
R21 (15h)
CLK_SRC_SEL
CLK_SYS_ENA
CLK_DSP_ENA
TO_ENA
15
2
0
0
0
0
0
Clock Rates 1
1 = FLL output
R22 (16h)
System Clock enable
0 = Disabled
Clock Rates 2
1 = Enabled
DSP Clock enable
0 = Disabled
1
1 = Enabled
Zero Cross timeout enable
0 = Disabled
0
1 = Enabled
R108 (6Ch)
WSMD_CLK_E
NA
Write Sequencer / Mic Detect Clock
Enable.
8
Write
Sequencer 0
0 = Disabled
1 = Enabled
Table 61 MCLK and CLK_SYS Control
CONTROL INTERFACE CLOCKING
Register map access is possible with or without a Master Clock (MCLK). However, if CLK_SYS_ENA
has been set to 1, then a Master Clock must be present for control register Read/Write operations. If
CLK_SYS_ENA = 1 and MCLK is not present, then register access will be unsuccessful. (Note that
read/write access to register R22, containing CLK_SYS_ENA, is always possible.)
If it cannot be assured that MCLK is present when accessing the register map, then it is required to
set CLK_SYS_ENA = 0 to ensure correct operation.
It is possible to use the WM8903 analogue bypass paths to the differential line outputs (LON/LOP and
RON/ROP) without MCLK. Note that MCLK is always required when using HPOUTL, HPOUTR,
LINEOUTL or LINEOUTR.
AUTOMATIC CLOCKING CONFIGURATION
The WM8903 supports a wide range of standard audio sample rates from 8kHz to 96kHz. The
Automatic Clocking Configuration mode simplifies the configuration of the clock dividers in the
WM8903 by deriving most of the necessary parameters from a minimum number of user registers.
The SAMPLE_RATE field selects the sample rate, fs, of the ADC and DAC. Note that the same
sample rate always applies to the ADC and DAC.
The CLK_SYS_RATE and CLK_SYS_MODE fields must be set according to the ratio of CLK_SYS to
fs. (Note that the internal clock CLK_SYS is derived from MCLK as controlled by MCLKDIV2). When
these fields are set correctly, the Sample Rate Decoder circuit automatically determines the clocking
configuration for all other circuits within the WM8903.
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The DSP clocking is enabled by CLK_DSP_ENA; see Table 61 for details of this register.
REGISTER
ADDRESS
BIT
13:10
9:8
LABEL
DEFAULT
0011
DESCRIPTION
R21 (15h)
CLK_SYS_RAT
E [3:0]
CLK_SYS_RATE and
CLK_SYS_MODE together
determine the clock division ratio
(CLK_SYS / fs); see Table 63
Clock Rates 1
CLK_SYS_MOD
E [1:0]
00
SAMPLE_RATE
[3:0]
Selects the Sample Rate (fs)
0000 = 8kHz
3:0
1000
0001 = 11.025kHz
0010 = 12kHz
0011 = 16kHz
0100 = 22.05kHz
0101 = 24kHz
0110 = 32kHz
0111 = 44.1kHz
1000 = 48kHz
1001 = 88.2kHz (Not available for
Digital Microphone. Not used for
88.2kHz ADC.)
1010 = 96kHz (Not available for
Digital Microphone. Not used for
96kHz ADC)
1011 to 1111 = Reserved
If the desired sample rate is not
listed in this table, then the closest
alternative should be chosen.
Table 62 Automatic Clocking Configuration Control
Available CLK_SYS / fs ratios
CLK_SYS_MODE
00
(default)
64
01
10
(USB modes)
68
136
0000
0001
0010
125
125
250
128
192
204
0011
256
272
250
0100
384
408
375
0101
512
544
500
0110
768
816
750
0111
1000
1001
1024
1408
1536
1088
1496
1632
Reserved
1000
1000
1500
1010 to 1111
Table 63 Sample Rate Decoder Control
The clock division ratios available with CLK_SYS_MODE = 00 are suitable for use with standard
audio master clocks. For example, with a 12.288MHz CLK_SYS and 48kHz sample rate, the
CLK_SYS to fs ratio is 256. In this case, the required setting for CLK_SYS_RATE is 0011, as shown
above.
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USB CLOCKING MODE
The clock division ratios with CLK_SYS_MODE = 01 or CLK_SYS_MODE = 10 allow compatibility
with a 12MHz USB clock, at sample rates up to 48kHz. For example, with a 12MHz (USB) clock and
8kHz sample rate, the CLK_SYS to fs ratio is 1500. In this case, the required setting for
CLK_SYS_RATE is 1001.
Note that 44.1kHz and related sample rates are approximate when derived from a USB clock. For
example, with a 12MHz MCLK and a division ratio of 272, the exact sample rate obtained is
44.118kHz rather than 44.1kHz. This 0.04% offset is inaudible and can be ignored. 48kHz and related
sample rates are exact in all modes of operation, provided that MCLK itself is exact.
ADC / DAC OPERATION AT 88.2K / 96K
The WM8903 supports ADC or DAC operation at 88.2kHz and 96kHz sample rates. This section
details specific conditions applicable to these operating modes. Note that simultaneous ADC and
DAC operation at 88.2kHz or 96kHz is not possible.
For DAC operation at 88.2kHz or 96kHz sample rates, the available clocking configurations are
detailed in Table 64.
Note that, for DAC operation at 88.2kHz or 96kHz sample rates, the ADCs must both be disabled
(ADCL_ENA = 0 and ADCR_ENA = 0). Also, the DAC_OSR register should be set to 0.
The CLK_SYS frequency is derived from MCLK. Note that the maximum MCLK frequency is defined
in the “Signal Timing Requirements” section.
SAMPLE RATE
REGISTER CONFIGURATION
CLK_SYS / fs RATIO
128 x fs
SAMPLE_RATE = 1001
CLK_SYS_MODE = 00
CLK_SYS_MODE = 01
CLK_SYS_MODE = 10
CLK_SYS_MODE = 00
CLK_SYS_MODE = 10
88.2kHz
CLK_SYS_RATE = 0001
136 x fs
125 x fs
SAMPLE_RATE = 1010
CLK_SYS_RATE = 0001
96kHz
128 x fs
125 x fs
Table 64 DAC Operation at 88.2kHz and 96kHz Sample Rates
For ADC operation at 88.2kHz or 96kHz sample rates, the available clocking configurations are
detailed in Table 65.
Note that ADC operation at these sample rates is achieved by setting the SAMPLE_RATE field to half
the required sample rate (eg. select 48kHz for 96kHz mode). In these modes, the BCLK_DIV field is
set to select BCLK at double the normal rate.
Note that, for ADC operation at 88.2kHz or 96kHz sample rates, the DACs must both be disabled
(DACL_ENA = 0 and DACR_ENA = 0).
The CLK_SYS frequency is derived from MCLK. Note that the maximum MCLK frequency is defined
in the “Signal Timing Requirements” section.
SAMPLE RATE
REGISTER CONFIGURATION
CLK_SYS / fs RATIO
SAMPLE_RATE = 0111
BCLK_DIV = 00010
88.2kHz
128 x fs
CLK_SYS_RATE = 0001
CLK_SYS_MODE = 00
LRCLK_RATE = 040h
SAMPLE_RATE = 1000
CLK_SYS_RATE = 0001
CLK_SYS_MODE = 00
BCLK_DIV = 00010
96kHz
128 x fs
LRCLK_RATE = 040h
Table 65 ADC Operation at 88.2kHz and 96kHz Sample Rates
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DIGITAL MICROPHONE (DMIC) OPERATION
When GPIO1/DMIC_LR is configured as DMIC_LR Clock output, the WM8903 outputs a clock which
supports Digital Microphone operation at a multiple of the ADC sampling rate. The precise clock
frequency varies according to the MCLK frequency, the SAMPLE_RATE field and other settings. The
clock frequency is always within the range 1MHz - 3MHz, and some examples are shown in Table 66.
SAMPLE
RATE
CLK_SYS
CLK_SYS
RATIO
DMIC_LR
FREQUENCY
DMIC_LR RATIO
8kHz
8kHz
12.288MHz
12MHz
1536fs
1500fs
768fs
750fs
256fs
250fs
256fs
272fs
375fs
500fs
1000fs
1.024MHz
1.200MHz
2.048MHz
2.400MHz
1.536MHz
2.400MHz
2.822MHz
3.000MHz
2.400MHz
2.400MHz
1.500MHz
128fs
150fs
128fs
150fs
32fs
16kHz
16kHz
48kHz
48kHz
44.1kHz
44.1kHz
32kHz
24kHz
12kHz
12.288MHz
12MHz
12.288MHz
12MHz
50fs
11.2896MHz
12MHz
64fs
68fs
12MHz
75fs
12MHz
100fs
125fs
12MHz
Table 66 Digital Microphone Clock
Note that the 88.2kHz and 96kHz sample rate settings are not valid for Digital Microphone operation.
FREQUENCY LOCKED LOOP (FLL)
The integrated FLL can be used to generate CLK_SYS from a wide variety of different reference
sources and frequencies. The FLL can use either MCLK, BCLK or LRC as its reference, which may
be a high frequency (eg. 12.288MHz) or low frequency (eg. 32.768kHz) reference. The FLL is tolerant
of jitter and may be used to generate a stable CLK_SYS from a less stable input signal. The FLL
characteristics are summarised in “Electrical Characteristics”.
Note that the FLL can be used to generate a free-running clock in the absence of an external
reference source. This is described in the “Free-Running FLL Clock” section below.
The FLL is enabled using the FLL_ENA register bit. Note that, when changing FLL settings, it is
recommended that the digital circuit be disabled via FLL_ENA and then re-enabled after the other
register settings have been updated. When changing the input reference frequency FREF, it is
recommended the FLL be reset by setting FLL_ENA to 0.
The FLL_CLK_SRC field allows MCLK, BCLK or LRC to be selected as the input reference clock.
The field FLL_CLK_REF_DIV provides the option to divide the input reference (MCLK, BCLK or LRC)
by 1, 2, 4 or 8. This field should be set to bring the reference down to 13.5MHz or below. For best
performance, it is recommended that the highest possible frequency - within the 13.5MHz limit -
should be selected.
The field FLL_CTRL_RATE controls internal functions within the FLL; it is recommended that only the
default setting be used for this parameter. FLL_GAIN controls the internal loop gain and should be set
to the recommended value quoted in Table 69.
The FLL output frequency is directly determined from FLL_FRATIO, FLL_OUTDIV and the real
number represented by FLL_N and FLL_K. The field FLL_N is an integer (LSB = 1); FLL_K is the
fractional portion of the number (MSB = 0.5). The fractional portion is only valid in Fractional Mode
when enabled by the field FLL_FRAC.
It is recommended that fractional Mode (FLL_FRAC = 1) is selected at all times. Power consumption
in the FLL is reduced in integer mode; however, the performance may also be reduced, with
increased noise or jitter on the output.
If low power consumption is required, then FLL settings must be chosen when N.K is an integer (ie.
FLL_K = 0). In this case, the fractional mode can be disabled by setting FLL_FRAC = 0.
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For best FLL performance, a non-integer value of N.K is required. In this case, the fractional mode
must be enabled by setting FLL_FRAC = 1. The FLL settings must be adjusted, if necessary, to
produce a non-integer value of N.K.
The FLL output frequency is generated according to the following equation:
FOUT = (FVCO / FLL_OUTDIV)
The FLL operating frequency, FVCO is set according to the following equation:
VCO = (FREF x N.K x FLL_FRATIO)
F
See Table 69 for the coding of the FLL_OUTDIV and FLL_FRATIO fields.
FREF is the input frequency, as determined by FLL_CLK_REF_DIV.
FVCO must be in the range 90-100 MHz. Frequencies outside this range cannot be supported.
Note that the output frequencies that do not lie within the ranges quoted above cannot be guaranteed
across the full range of device operating temperatures.
In order to follow the above requirements for FVCO, the value of FLL_OUTDIV should be selected
according to the desired output FOUT, as described in Table 67. The divider, FLL_OUTDIV, must be
set so that FVCO is in the range 90-100MHz.
OUTPUT FREQUENCY FOUT
2.8125 MHz - 3.125 MHz
5.625 MHz - 6.25 MHz
FLL_OUTDIV
4h (divide by 32)
3h (divide by 16)
2h (divide by 8)
1h (divide by 4)
11.25 MHz - 12.5 MHz
22.5 MHz - 25 MHz
Table 67 Selection of FLL_OUTDIV
The value of FLL_FRATIO should be selected as described in Table 68.
REFERENCE FREQUENCY FREF
1MHz - 13.5MHz
FLL_FRATIO
0h (divide by 1)
256kHz - 1MHz
1h (divide by 2)
2h (divide by 4)
3h (divide by 8)
4h (divide by 16)
128kHz - 256kHz
64kHz - 128kHz
Less than 64kHz
Table 68 Selection of FLL_FRATIO
In order to determine the remaining FLL parameters, the FLL operating frequency, FVCO, must be
calculated, as given by the following equation:
FVCO = (FOUT x FLL_OUTDIV)
The value of FLL_N and FLL_K can then be determined as follows:
N.K = FVCO / (FLL_FRATIO x FREF
)
See Table 69 for the coding of the FLL_OUTDIV and FLL_FRATIO fields.
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Note that FREF is the input frequency, after division by FLL_CLK_REF_DIV, where applicable.
In FLL Fractional Mode, the fractional portion of the N.K multiplier is held in the FLL_K register field.
This field is coded as a fixed point quantity, where the MSB has a weighting of 0.5. Note that, if
desired, the value of this field may be calculated by multiplying K by 216 and treating FLL_K as an
integer value, as illustrated in the following example:
If N.K = 8.192, then K = 0.192
Multiplying K by 216 gives 0.192 x 65536 = 12582.912 (decimal)
Apply rounding to the nearest integer = 12583 (decimal) = 3127 (hex)
For best performance, FLL Fractional Mode should always be used. Therefore, if the calculations
yield an integer value of N.K, then it is recommended to adjust FLL_FRATIO in order to obtain a non-
integer value of N.K. Care must always be taken to ensure that the FLL operating frequency, FVCO, is
within its recommended limits of 90-100 MHz.
The register fields that control the FLL are described in Table 69. Example settings for a variety of
reference frequencies and output frequencies are shown in Table 70.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R128 (80h)
FLL_GAIN [3:0]
Gain applied to error
7:4
0h
FLL Control 1
0000 = x 1 (Recommended value)
0001 = x 2
0010 = x 4
0011 = x 8
0100 = x 16
0101 = x 32
0110 = x 64
0111 = x 128
1000 = x 256
Recommended that this register is not
changed from default.
FLL_HOLD
FLL_FRAC
FLL Hold Select
0 = Disabled
1 = Enabled
3
2
0
0
This feature enables free-running
mode in FLL when reference clock is
removed
Fractional enable
0 = Integer Mode
1 = Fractional Mode
Fractional Mode is recommended in all
cases
FLL_ENA
FLL Enable
0 = Disabled
1 = Enabled
FLL Clock source
00 = MCLK
0
0
R129 (81h)
FLL_CLK_SRC
[1:0]
12:11
00
FLL Control 2
01 = BCLK
10 = LRC
11 = Reserved
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
FLL_CLK_REF
_DIV [1:0]
FLL Clock Reference Divider
00 = MCLK / 1
10:9
00
01 = MCLK / 2
10 = MCLK / 4
11 = MCLK / 8
MCLK (or other input reference) must
be divided down to <=13.5MHz.
For lower power operation, the
reference clock can be divided down
further if desired.
FLL_CTRL_RA
TE [2:0]
Frequency of the FLL control block
000 = FVCO / 1 (Recommended value)
001 = FVCO / 2
8:6
000
010 = FVCO / 3
011 = FVCO / 4
100 = FVCO / 5
101 = FVCO / 6
110 = FVCO / 7
111 = FVCO / 8
Recommended that this register is not
changed from default.
FLL_OUTDIV
[2:0]
FOUT clock divider
5:3
000
000 = 2
001 = 4
010 = 8
011 = 16
100 = 32
101 = 64
110 = 128
111 = 256
(FOUT = FVCO / FLL_OUTDIV)
FLL_FRATIO
[2:0]
FVCO clock divider
2:0
000
000 = divide by 1
001 = divide by 2
010 = divide by 4
011 = divide by 8
1XX = divide by 16
000 recommended for FREF > 1MHz
100 recommended for FREF < 64kHz
Fractional multiply for FREF
(MSB = 0.5)
R130 (82h)
FLL_K [15:0]
FLL_N [9:0]
15:0
9:0
0000h
000h
FLL Control 3
R131 (83h)
Integer multiply for FREF
(LSB = 1)
FLL Control 4
Table 69 FLL Register Map
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FREE-RUNNING FLL CLOCK
The FLL can generate a clock signal even when the external reference is removed. It should be noted
that the accuracy of this clock is reduced, and a reference source should always be used where
possible. In free-running modes, the FLL is not sufficiently accurate for hi-fi audio applications. The
free-running modes are suitable for clocking other functions, including the Write Sequencer and DC
servo control. The free-running mode can be used to support the analogue input (bypass) audio
paths.
A clock reference is required for initial configuration of the FLL as described above. For free-running
operation, the FLL_HOLD bit should be set, as described in Table 69. When FLL_HOLD is set, the
FLL will continue to generate a stable output clock after the reference input is stopped or
disconnected.
Note that the FLL must be selected as the CLK_SYS source by setting CLK_SRC_SEL (see Table
61). Note that, in the absence of any reference clock, the FLL output is subject to a very wide
tolerance. See “Electrical Characteristics” for details of the FLL accuracy.
GPIO OUTPUTS FROM FLL
The WM8903 has an internal signal which indicates whether the FLL Lock has been achieved. The
FLL Lock status is an input to the Interrupt control circuit and can be used to trigger an Interrupt event
- see “Interrupts”.
The FLL Lock signal can be output directly on a GPIO pin as an external indication of FLL Lock. See
“General Purpose Input/Output (GPIO)” for details of how to configure a GPIO pin to output the FLL
Lock signal.
The FLL Clock can be output directly on a GPIO pin as a clock signal for other circuits. Note that the
FLL Clock may be output even if the FLL is not selected as the WM8903 CLK_SYS source. The
clocking configuration is illustrated in Figure 55. See “General Purpose Input/Output (GPIO)” for
details of how to configure a GPIO pin to output the FLL Clock.
EXAMPLE FLL CALCULATION
To generate 12.288 MHz output (FOUT) from a 12.000 MHz reference clock (FREF):
Set FLL_CLK_REF_DIV in order to generate FREF <=13.5MHz:
FLL_CLK_REF_DIV = 00 (divide by 1)
Set FLL_CTRL_RATE to the recommended setting:
FLL_CTRL_RATE = 000 (divide by 1)
Set FLL_GAIN to the recommended setting:
FLL_GAIN = 0000 (multiply by 1)
Set FLL_OUTDIV for the required output frequency as shown in Table 67:-
FOUT = 12.288 MHz, therefore FLL_OUTDIV = 2h (divide by 8)
Set FLL_FRATIO for the given reference frequency as shown in Table 68:
REF = 12MHz, therefore FLL_FRATIO = 0h (divide by 1)
F
Calculate FVCO as given by FVCO = FOUT x FLL_OUTDIV:-
VCO = 12.288 x 8 = 98.304MHz
F
Calculate N.K as given by N.K = FVCO / (FLL_FRATIO x FREF):
N.K = 98.304 / (1 x 12) = 8.192
Determine FLL_N and FLL_K from the integer and fractional portions of N.K:-
FLL_N is 8. FLL_K is 0.192
Confirm that N.K is a fractional quantity and set FLL_FRAC:
N.K is fractional. Set FLL_FRAC = 1.
Note that, if N.K is an integer, then an alternative value of FLL_FRATIO should be selected
in order to produce a fractional value of N.K.
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EXAMPLE FLL SETTINGS
Table 70 provides example FLL settings for generating common CLK_SYS frequencies from a variety
of low and high frequency reference inputs.
FREF
FOUT
FLL_CLK_
REF_DIV
FVCO
FLL_N
FLL_K
FLL_
FRATIO
FLL_
OUTDIV
FLL_
FRAC
32.000
kHz
12.288
MHz
Divide by 1
(0h)
98.304
MHz
192
0
16
8
0
1
1
1
1
0
1
1
1
0
1
1
1
1
1
(0C0h)
176
(0000h)
0.4
(4h)
16
(2h)
8
32.000
kHz
11.2896
MHz
Divide by 1
(0h)
90.3168
MHz
(0B0h)
187
(6666h)
0.5
(4h)
16
(2h)
8
32.768
kHz
12.288
MHz
Divide by 1
(0h)
98.304
MHz
(0BBh)
172
(8000h)
0.25
(4h)
16
(2h)
8
32.768
kHz
11.288576 Divide by 1
90.3086
MHz
MHz
(0h)
(0ACh)
172
(4000h)
0.2656
(4400h)
0
(4h)
16
(2h)
8
32.768
kHz
11.2896
MHz
Divide by 1
(0h)
90.3168
MHz
(0ACh)
128
(4h)
16
(2h)
8
48
12.288
MHz
Divide by 1
(0h)
98.304
MHz
kHz
(080h)
8
(0000h)
0.707483
(B51Eh)
0.192
(4h)
1
(2h)
8
11.3636
MHz
12.368544 Divide by 1
98.9484
MHz
MHz
(0h)
(008h)
8
(0h)
1
(2h)
8
12.000
MHz
12.288
MHz
Divide by 1
(0h)
98.304
MHz
(008h)
7
(3127h)
0.526398
(86C2h)
0
(0h)
1
(2h)
8
12.000
MHz
11.289597 Divide by 1
90.3168
MHz
MHz
(0h)
(007h)
8
(0h)
1
(2h)
8
12.288
MHz
12.288
MHz
Divide by 1
(0h)
98.304
MHz
(008h)
7
(0000h)
0.35
(0h)
1
(2h)
8
12.288
MHz
11.2896
MHz
Divide by 1
(0h)
90.3168
MHz
(007h)
7
(599Ah)
0.56184
(8FD5h)
0.94745
(F28Ch)
0.23999
(3D70h)
0.40799
(6872h)
(0h)
1
(2h)
8
13.000
MHz
12.287990 Divide by 1
MHz (0h)
11.289606 Divide by 1
MHz (0h)
12.287988 Divide by 2
MHz (1h)
11.289588 Divide by 2
MHz (1h)
98.3039
MHz
(007h)
6
(0h)
1
(2h)
8
13.000
MHz
90.3168
MHz
(006h)
10
(0h)
1
(2h)
8
19.200
MHz
98.3039
MHz
(00Ah)
9
(0h)
1
(2h)
8
19.200
MHz
90.3167
MHz
(009h)
(0h)
(2h)
Table 70 Example FLL Settings
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WM8903
GENERAL PURPOSE INPUT/OUTPUT (GPIO)
The WM8903 provides five multi-function pins which can be configured to provide a number of
different functions. These are digital input/output pins on the DBVDD power domain. The GPIO pins
are:
GPIO1/DMIC_LR
GPIO2/DMIC_DAT
GPIO3/ADDR
INTERRUPT (GPIO4)
BCLK (GPIO5)
Each general purpose I/O pin can be configured to be a GPIO input or configured as one of a number
of output functions. Signal de-bouncing can be selected on GPIO input pins for use with jack/button
detect applications. Table 71 lists the functions that are available on each of these pins. The default
function is highlighted for each pin.
GPIO PINS
GPIO Pin Function
GPIO1/D GPIO2/D
MIC_LR MIC_DAT
GPIO3/
ADDR
INTERRUPT
(GPIO4)
BCLK
(GPIO5)
GPIO output
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Yes
Yes
No
BCLK input/output
Interrupt output (IRQ)
Yes
Yes
No
Yes
No
Yes
No
Yes
No
Digital Microphone Clock (DMIC_LR)
Digital Microphone Data (DMIC_DAT)
GPIO input
Yes
Yes
No
No
No
Yes
Yes
Yes
Yes
(including jack/button detect)
MICBIAS Current detect output
MICBIAS Short Circuit detect output
FLL Lock output
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
FLL Clock output
Table 71 GPIO Functions Available
The register fields that control the functionality of these pins are described in Table 72. For each pin,
the selected function is determined by the GPn_FN field, where n identifies the GPIO pin (1 to 5).
Note that the INTERRUPT pin is also referred to as GPIO4; the BCLK pin is also referred to as
GPIO5.
The pin direction, set by GPn_DIR, must be set according to the function selected by GPn_FN.
The characteristics of any pin selected as an output may be controlled by setting GPn_OP_CFG - an
output pin may be either CMOS or Open-Drain. When a pin is configured as a GPIO output, its level
can be set to logic 0 or logic 1 using the GPn_LVL field.
A pin configured as a GPIO input can be used to trigger an Interrupt event. This input may be
configured as active high or active low using the GPn_IP_CFG field. De-bouncing of this input may be
enabled using the GPn_DB field. Internal pull-up and pull-down resistors may be enabled using the
GPn_PU and GPn_PD fields. (Note that if GPn_PU and GPn_PD are both set for any GPIO pin, then
the pull-up and pull-down will be disabled.)
Each of the GPIO pins is an input to the Interrupt control circuit and can be used to trigger an Interrupt
event. The register field GPn_INTMODE selects edge detect or level detect Interrupt functionality.
Edge detect raises an interrupt on rising and falling transitions. Level detect asserts the interrupt for
as long as the GPIO status is asserted. See “Interrupts”.
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The Digital Microphone Interface and MICBIAS Current Detect functions are described in the
“Analogue Input Signal Path” section.
Interrupt Output is the default function of GPIO4. See “Interrupts” for further details.
BCLK is the default function of GPIO5. This may be input or output. Note that, when BCLK is enabled
on this pin (GP5_FN = 1h), the other GPIO control fields for this pin have no effect. When BCLK is not
enabled on this pin (GP5_FN ≠ 1h), the WM8903 uses the MCLK input as the Bit Clock. See “Digital
Audio Interface Control” for further details.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R116 (74h)
GP1_FN [5:0]
GPIO 1 Pin Function select
00h = GPIO output
13:8
00_0000
GPIO Control
1
01h = Reserved
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = DMIC_LR Clock output
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GP1_DIR
GPIO Pin Direction
0 = Output
7
6
5
4
1
0
1
0
1 = Input
GP1_OP_CFG
GP1_IP_CFG
GP1_LVL
Output pin configuration
0 = CMOS
1 = Open-drain
Input pin configuration
0 = Active low
1 = Active high
GPIO Output Level
(when GP1_FN = 00000)
0 = Logic 0
1 = Logic 1
GP1_PD
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
0 = Level triggered
1 = Edge triggered
GPIO de-bounce
3
2
1
0
1
0
0
0
GP1_PU
GP1_INTMODE
GP1_DB
0 = GPIO is not debounced
1 = GPIO is debounced
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R117 (75h)
GPIO Control
2
GP2_FN [5:0]
GPIO 2 Pin Function select
00h = GPIO output
13:8
00_0000
01h = Reserved
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = DMIC_DAT Data input
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GP2_DIR
GPIO Pin Direction
0 = Output
7
6
5
4
1
0
1
0
1 = Input
GP2_OP_CFG
GP2_IP_CFG
GP2_LVL
Output pin configuration
0 = CMOS
1 = Open-drain
Input pin configuration
0 = Active low
1 = Active high
GPIO Output Level
(when GP2_FN = 00000)
0 = Logic 0
1 = Logic 1
GP2_PD
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
0 = Level triggered
1 = Edge triggered
3
2
1
GP2_PU
0
GP2_INTMODE
GP2_DB
1
0
0
GPIO de-bounce
0
0 = GPIO is not debounced
1 = GPIO is debounced
GPIO 3 Pin Function select
00h = GPIO output
01h = Reserved
R118 (76h)
GPIO Control
3
GP3_FN [5:0]
13:8
00_0000
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = Reserved
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GP3_DIR
GPIO Pin Direction
0 = Output
7
1
1 = Input
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
GP3_OP_CFG
Output pin configuration
0 = CMOS
6
0
1 = Open-drain
GP3_IP_CFG
GP3_LVL
Input pin configuration
0 = Active low
5
4
1
0
1 = Active high
GPIO Output Level
(when GP3_FN = 00000)
0 = Logic 0
1 = Logic 1
GP3_PD
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
0 = Level triggered
1 = Edge triggered
3
2
1
GP3_PU
0
GP3_INTMODE
GP3_DB
1
0
0
0
GPIO de-bounce
0 = GPIO is not debounced
1 = GPIO is debounced
GPIO 4 Pin Function select
00h = GPIO output
R119 (77h)
GPIO Control
4
GP4_FN [5:0]
13:8
00_0010
01h = Reserved
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = Reserved
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GP4_DIR
GPIO Pin Direction
0 = Output
7
6
5
4
0
0
1
0
1 = Input
GP4_OP_CFG
GP4_IP_CFG
GP4_LVL
Output pin configuration
0 = CMOS
1 = Open-drain
Input pin configuration
0 = Active low
1 = Active high
GPIO Output Level
(when GP4_FN = 00000)
0 = Logic 0
1 = Logic 1
GP4_PD
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
3
0
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REGISTER
ADDRESS
BIT
LABEL
GP4_PU
DEFAULT
DESCRIPTION
GPIO Pull-Up Enable
0 = Pull-up disabled
2
0
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
GP4_INTMODE
GP4_DB
1
0
0
0
0 = Level triggered
1 = Edge triggered
GPIO de-bounce
0 = GPIO is not debounced
1 = GPIO is debounced
GPIO 5 Pin Function select
00h = GPIO output
R120 (78h)
GPIO Control
5
GP5_FN [5:0]
13:8
00_0001
01h = BCLK
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = Reserved
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GP5_DIR
GPIO Pin Direction
0 = Output
7
6
5
4
1
0
1
0
1 = Input
GP5_OP_CFG
GP5_IP_CFG
GP5_LVL
Output pin configuration
0 = CMOS
1 = Open-drain
Input pin configuration
0 = Active low
1 = Active high
GPIO Output Level
(when GP5_FN = 00000)
0 = Logic 0
1 = Logic 1
GP5_PD
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
0 = Level triggered
1 = Edge triggered
3
2
1
0
0
0
0
0
GP5_PU
GP5_INTMODE
GP5_DB
GPIO de-bounce
0 = GPIO is not debounced
1 = GPIO is debounced
Table 72 GPIO Control
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INTERRUPTS
The Interrupt Controller has multiple inputs. These include the GPIO input pins and the MICBIAS
current detection circuits. Any combination of these inputs can be used to trigger an Interrupt (IRQ)
event.
There is an Interrupt Status field associated with each of the IRQ inputs. These are contained in the
Interrupt Status Register (R121), as described in Table 73. The status of the IRQ inputs can be read
from this register at any time, or else in response to the Interrupt Output being signalled via a GPIO
pin.
The Interrupt Output represents the logical ‘OR’ of all the unmasked IRQ inputs. The bits within the
Interrupt Status register (R121) are latching fields and, once they are set, they are not reset until the
Status Register is read. Accordingly, the Interrupt Output is not reset until each of the unmasked IRQ
inputs has been read. Note that, if the condition that caused the IRQ input to be asserted is still valid,
then the Interrupt Output will remain set even after the Status register has been read.
Each of the IRQ inputs can be individually masked or enabled as an input to the Interrupt function,
using the bits contained in the Interrupt Status Mask register (R122). Note that the interrupt status
fields remain valid, even when masked, but the masked bits will not cause the Interrupt Output to be
asserted.
When a GPIO input is used as Interrupt event, the polarity can be set using GP_IP_CFG as described
in Table 72. The polarity of the MICBIAS detection functions can be set using MICDET_INV and
MICSHRT_INV as described in Table 73; this allows the IRQ event to be used to indicate either the
removal or insertion of a microphone accessory. The polarity of the FLL Lock indication can be set
using FLL_LOCK_INV; this allows the IRQ event to be used to indicate either the FLL Lock or the FLL
Not-Locked status.
By default, the Interrupt Output is Active High. The polarity can be inverted using IRQ_POL.
The Interrupt Output may be configured the INTERRUPT/GPIO4 pin or on the GPIO1/DMIC_LR,
GPIO2/DMIC_DAT, GPIO3/ADDR or BCLK/GPIO5 pins. Interrupt Output is the default function on the
INTERRUPT pin (GP4_FN = 2h), but the INTERRUPT pin can also be used to support other
functions. See “General Purpose Input/Output (GPIO)” for details of how to configure GPIO pins for
Interrupt (IRQ) output.
The WM8903 Interrupt Controller circuit is illustrated in Figure 54. The associated control fields are
described in Table 73.
MIC_SHORT_IRQ
MICSHRT_EINT
MICSHRT_INV
IM_MICSHRT_EINT
MICDET_EINT
MIC_DETECT_IRQ
FLL_LOCK_IRQ
MICDET_INV
IM_MICDET_EINT
FLL_LOCK_EINT
IM_FLL_LOCK_EINT
FLL_LOCK_INV
Status
WSEQ_BUSY_EINT
WSEQ_BUSY_IRQ
GPIO5_IRQ
Register
IM_WSEQ_BUSY_EINT
Latches
GP5_EINT
Read only;
INTERRUPT
IM_GP5_EINT
IM_GP4_EINT
IM_GP3_EINT
IM_GP2_EINT
IM_GP1_EINT
IRQ_POL
cleared on
register
read
GP4_EINT
GP3_EINT
GP2_EINT
GP1_EINT
GPIO4_IRQ
GPIO3_IRQ
GPIO2_IRQ
GPIO1_IRQ
Figure 56 Interrupt Controller
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R121 (79h)
MICSHRT_EINT
MICBIAS Short Circuit detect IRQ
status
15
0
Interrupt
Status 1
0 = Short Circuit current IRQ not set
1 = Short Circuit current IRQ set
(Read-Only Register)
MICDET_EINT
MICBIAS Current detect IRQ status
0 = Current detect IRQ not set
1 = Current detect IRQ set
(Read-Only Register)
14
13
0
0
WSEQ_BUSY_E
INT
Write Sequencer Busy IRQ status
0 = WSEQ IRQ not set
1 = WSEQ IRQ set
The Write Sequencer asserts this
flag when it has completed a
programmed sequence - ie it
indicates that the Write Sequencer
is NOT Busy.
(Read-Only Register)
FLL Lock IRQ status
0 = FLL Lock IRQ not set
1 = FLL Lock IRQ set
(Read-Only Register)
GPIO5 IRQ status
FLL_LOCK_EIN
T
5
4
3
2
1
0
0
0
0
0
0
0
GP5_EINT
GP4_EINT
GP3_EINT
GP2_EINT
GP1_EINT
0 = GPIO5 IRQ not set
1 = GPIO5 IRQ set
(Read-Only Register)
GPIO4 IRQ status
0 = GPIO4 IRQ not set
1 = GPIO4 IRQ set
(Read-Only Register)
GPIO3/ADDR IRQ status
0 = GPIO3 IRQ not set
1 = GPIO3 IRQ set
(Read-Only Register)
GPIO2/DMIC_DAT IRQ status
0 = GPIO2 IRQ not set
1 = GPIO2 IRQ set
(Read-Only Register)
GPIO1/DMIC_LR IRQ status
0 = GPIO1 IRQ not set
1 = GPIO1 IRQ set
(Read-Only Register)
R122 (7Ah)
IM_MICSHRT_E
INT
Interrupt mask for MICBIAS Short
Circuit detect
15
14
13
1
1
1
Interrupt
Status 1 Mask
0 = Not masked
1 = Masked
IM_MICDET_EI
NT
Interrupt mask for MICBIAS Current
detect
0 = Not masked
1 = Masked
IM_WSEQ_BUS
Y_EINT
Interrupt mask for WSEQ Busy
indication
0 = Not masked
1 = Masked
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DESCRIPTION
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
IM_FLL_LOCK_
EINT
Interrupt mask for FLL Lock
0 = Not masked
5
1
1 = Masked
IM_GP5_EINT
IM_GP4_EINT
IM_GP3_EINT
IM_GP2_EINT
Interrupt mask for GPIO5
0 = Not masked
4
3
2
1
1
1
1
1
1 = Masked
Interrupt mask for GPIO4
0 = Not masked
1 = Masked
Interrupt mask for GPIO3/ADDR
0 = Not masked
1 = Masked
Interrupt mask for
GPIO2/DMIC_DAT
0 = Not masked
1 = Masked
IM_GP1_EINT
MICSHRT_INV
Interrupt mask for GPIO1/DMIC_LR
0 = Not masked
0
1
0
1 = Masked
R123 (7Bh)
MICBIAS Short Circuit detect
polarity
15
Interrupt
0 = Detect current increase above
threshold
Polarity 1
1 = Detect current decrease below
threshold
MICDET_INV
MICBIAS Current Detect polarity
0 = Detect current increase above
threshold
14
0
1 = Detect current decrease below
threshold
FLL_LOCK_INV
IRQ_POL
FLL Lock polarity
0 = Non-inverted
1 = Inverted
5
0
0
0
R126 (7Eh)
Interrupt
Control
Interrupt Output polarity
0 = Active high
1 = Active low
Table 73 Interrupt Control
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WM8903
CONTROL INTERFACE
The WM8903 is controlled by writing to registers through a 2-wire serial control interface. Readback is
available for all registers, including Chip ID, power management status and GPIO status.
Note that, if it cannot be assured that MCLK is present when accessing the register map, then it is
required to set CLK_SYS_ENA = 0 to ensure correct operation. See “Clocking and Sample Rates” for
further details and for the definition of CLK_SYS_ENA.
The WM8903 is a slave device on the control interface; SCLK is a clock input, while SDIN is a bi-
directional data pin. To allow arbitration of multiple slaves (and/or multiple masters) on the same
interface, the WM8903 transmits logic 1 by tri-stating the SDIN pin, rather than pulling it high. An
external pull-up resistor is required to pull the SDIN line high so that the logic 1 can be recognised by
the master.
In order to allow many devices to share a single 2-wire control bus, every device on the bus has a
unique 8-bit device ID (this is not the same as the 8-bit address of each register in the WM8903). The
default device ID for the WM8903 is 0011 0100 (34h). The LSB of the device ID is the Read/Write bit;
this bit is set to logic 1 for “Read” and logic 0 for “Write”.
Alternatively, the device ID can be set to 0011 0110 (0x36) by pulling the GPIO3/ADDR pin high
during device start-up, when the internal power-on reset signal PORB (see “Power-on Reset”) is
released. The setup and hold times for device ID selection are shown in Table 74. After the device ID
has been selected, the GPIO3/ADDR pin can be used as a GPIO.
SYMBOL
Tpusetup
MIN
100
100
TYP
MAX
UNIT
µs
Tpuhold
µs
Table 74 GPIO3/ADDR Latch on Power-up Timing
The WM8903 operates as a slave device only. The controller indicates the start of data transfer with a
high to low transition on SDIN while SCLK remains high. This indicates that a device ID, register
address and data will follow. The WM8903 responds to the start condition and shifts in the next eight
bits on SDIN (8-bit device ID, including Read/Write bit, MSB first). If the device ID received matches
the device ID of the WM8903, then the WM8903 responds by pulling SDIN low on the next clock
pulse (ACK). If the device ID is not recognised or the R/W bit is ‘1’ when operating in write only mode,
the WM8903 returns to the idle condition and waits for a new start condition and valid address.
If the device ID matches the device ID of the WM8903, the data transfer continues as described
below. The controller indicates the end of data transfer with a low to high transition on SDIN while
SCLK remains high. After receiving a complete address and data sequence the WM8903 returns to
the idle state and waits for another start condition. If a start or stop condition is detected out of
sequence at any point during data transfer (i.e. SDIN changes while SCLK is high), the device returns
to the idle condition.
The WM8903 supports the following read and write operations:
Single write
Single read
Multiple write using auto-increment
Multiple read using auto-increment
The sequence of signals associated with a single register write operation is illustrated in Figure 57.
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Figure 57 Control Interface Register Write
The sequence of signals associated with a single register read operation is illustrated in Figure 58.
Figure 58 Control Interface Register Read
The Control Interface also supports other register operations, as listed above. The interface protocol
for these operations is summarised below. The terminology used in the following figures is detailed in
Table 75.
Note that multiple write and multiple read operations are supported using the auto-increment mode.
This feature enables the host processor to access sequential blocks of the data in the WM8903
register map faster than is possible with single register operations.
TERMINOLOGY
DESCRIPTION
Start Condition
S
Sr
Repeated start
A
Acknowledge (SDIN Low)
Not Acknowledge (SDIN High)
Stop Condition
¯A¯
P
R/¯W¯
ReadNotWrite
0 = Write
1 = Read
[White field]
[Grey field]
Data flow from bus master to WM8903
Data flow from WM8903 to bus master
Table 75 Control Interface Terminology
Figure 59 Single Register Write to Specified Address
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WM8903
Figure 60 Single Register Read from Specified Address
Figure 61 Multiple Register Write to Specified Address using Auto-increment
Read from 'Register Address'
MSByte Data 0 LSByte Data 0
S
Device ID
A
Register Address
A
Sr
Device ID
A
A
A
RW
RW
(0)
(1)
Read from 'Last Register Address+N-1'
MSByte Data N-1 LSByte Data N-1
Read from 'Last Register Address+N'
MSByte Data N LSByte Data N
A
A
A
A
A
P
Figure 62 Multiple Register Read from Specified Address using Auto-increment
Figure 63 Multiple Register Read from Last Address using Auto-increment
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CONTROL WRITE SEQUENCER
The Control Write Sequencer is a programmable unit that forms part of the WM8903 control interface
logic. It provides the ability to perform a sequence of register write operations with the minimum of
demands on the host processor - the sequence may be initiated by a single operation from the host
processor and then left to execute independently.
Default sequences for Start-Up and Shut-Down are provided (see “Default Sequences” section). It is
recommended that these default sequences are used unless changes become necessary.
When a sequence is initiated, the sequencer performs a series of pre-defined register writes. The
host processor informs the sequencer of the start index of the required sequence within the
sequencer’s memory. At each step of the sequence, the contents of the selected register fields are
read from the sequencer’s memory and copied into the WM8903 control registers. This continues
sequentially through the sequencer’s memory until an “End of Sequence” bit is encountered; at this
point, the sequencer stops and an Interrupt status flag is asserted. For cases where the timing of the
write sequence is important, a programmable delay can be set for specific steps within the sequence.
Note that the Control Write Sequencer’s internal clock is derived from the internal clock CLK_SYS. An
external MCLK signal must be present when using the Control Write Sequencer, and CLK_SYS must
be enabled by setting CLK_SYS_ENA (see “Clocking and Sample Rates”). The clock division from
MCLK is handled transparently by the WM8903 without user intervention, as long as MCLK and
sample rates are set correctly.
INITIATING A SEQUENCE
The Register fields associated with running the Control Write Sequencer are described in Table 76.
The Write Sequencer Clock is enabled by setting the WSMD_CLK_ENA bit. Note that the operation of
the Control Write Sequencer also requires the internal clock CLK_SYS to be enabled via the
CLK_SYS_ENA (see “Clocking and Sample Rates”).
The start index of the required sequence must be written to the WSEQ_START_INDEX field. Setting
the WSEQ_START bit initiates the sequencer at the given start index.
The Write Sequencer can be interrupted by writing a logic 1 to the WSEQ_ABORT bit.
The current status of the Write Sequencer can be read using two further register fields - when the
WSEQ_BUSY bit is asserted, this indicates that the Write Sequencer is busy. Note that, whilst the
Control Write Sequencer is running a sequence (indicated by the WSEQ_BUSY bit), normal
read/write operations to the Control Registers cannot be supported. (The Write Sequencer registers
and the Software Reset register can still be accessed when the Sequencer is busy.) The index of the
current step in the Write Sequencer can be read from the WSEQ_CURRENT_INDEX field; this is an
indicator of the sequencer’s progress. On completion of a sequence, this field holds the index of the
last step within the last commanded sequence.
When the Write Sequencer reaches the end of a sequence, it asserts the WSEQ_BUSY_EINT flag in
Register R121 (see Table 73 within the “Interrupts” section). This flag can be used to generate an
Interrupt Event on completion of the sequence. Note that the WSEQ_BUSY_EINT flag is asserted to
indicate that the WSEQ is NOT Busy.
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R108 (6Ch)
WSMD_CLK_EN
A
Write Sequencer / Mic Detect Clock
Enable.
8
0
Write
Sequencer 0
0 = Disabled
1 = Enabled
R111 (6Fh)
WSEQ_ABORT
WSEQ_START
Writing a 1 to this bit aborts the
current sequence and returns control
of the device back to the serial
control interface.
9
8
0
0
Write
Sequencer 3
(Write-Only Register)
Writing a 1 to this bit starts the write
sequencer at the memory location
indicated by the
WSEQ_START_INDEX field. The
sequence continues until it reaches
an “End of sequence” flag. At the end
of the sequence, this bit will be reset
by the Write Sequencer.
(Write-Only Register)
WSEQ_START_
INDEX [5:0]
Sequence Start Index. This is the
memory location of the first command
in the selected sequence.
5:0
00_0000
0 to 31 = RAM addresses
32 to 48 = ROM addresses
49 to 63 = Reserved
R112 (70h)
WSEQ_CURRE
NT_INDEX [5:0]
Sequence Current Index. This is the
location of the most recently
accessed command in the write
sequencer memory.
9:4
00_0000
Write
Sequencer 4
(Read-Only Register)
Sequencer Busy flag
0 = Sequencer idle
1 = Sequencer busy
WSEQ_BUSY
0
0
Note: it is not possible to write to
control registers via the control
interface while the Sequencer is
Busy.
(Read-Only Register)
Table 76 Write Sequencer Control – Initiating a Sequence
PROGRAMMING A SEQUENCE
A sequence consists of write operations to data bits (or groups of bits) within the control registers.
The Register fields associated with programming the Control Write Sequencer are described in Table
77.
For each step of the sequence being programmed, the Sequencer Index must be written to the
WSEQ_WRITE_INDEX field. The values 0 to 31 correspond to all the available RAM addresses
within the Write Sequencer memory. (Note that memory addresses 32 to 48 also exist, but these are
ROM addresses, which are not programmable.)
Having set the Index as described above, Register R109 must be written to (containing the Control
Register Address, the Start Bit Position and the Field Width applicable to this step of the sequence).
Also, Register R110 must be written to (containing the Register Data, the End of Sequence flag and
the Delay time required after this step is executed). After writing to these two registers, the next step
in the sequence may be programmed by updating WSEQ_WRITE_INDEX and repeating the
procedure.
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WSEQ_ADDR is an 8-bit field containing the Control Register Address in which the data should be
written.
WSEQ_DATA_START is a 4-bit field which identifies the LSB position within the selected Control
Register to which the data should be written. Setting WSEQ_DATA_START = 0100 will cause 1-bit
data to be written to bit 4. With this setting, 4-bit data would be written to bits 7:4 and so on.
WSEQ_DATA_WIDTH is a 3-bit field which identifies the width of the data block to be written. This
enables selected portions of a Control Register to be updated without any concern for other bits within
the same register, eliminating the need for read-modify-write procedures. Values of 0 to 7 correspond
to data widths of 1 to 8 respectively. For example, setting WSEQ_DATA_WIDTH = 010 will cause a
3-bit data block to be written. Note that the maximum value of this field corresponds to an 8-bit data
block; writing to register fields greater than 8 bits wide must be performed using two separate
operations of the Control Write Sequencer.
WSEQ_DATA is an 8-bit field which contains the data to be written to the selected Control Register.
The WSEQ_DATA_WIDTH field determines how many of these bits are written to the selected
register; the most significant bits (above the number indicated by WSEQ_DATA_WIDTH) are ignored.
WSEQ_DELAY is a 4-bit field which controls the waiting time between the current step and the next
step in the sequence. The total delay time per step (including execution) is given by:
T = k × (2 WSEQ_DELAY + 8)
where k = 62.5s (under recommended operating conditions)
This gives a useful range of execution/delay times from 562s up to 2.048s per step.
WSEQ_EOS is a 1-bit field which indicates the End of Sequence. If this bit is set, then the Control
Write Sequencer will automatically stop after this step has been executed.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R108 (6Ch)
Write
Sequencer 0
WSEQ_WRIT
E_INDEX [4:0]
Sequence Write Index. This is the
memory location to which any updates to
R109 and R110 will be copied.
4:0
0_0000
0 to 31 = RAM addresses
Width of the data block written in this
sequence step.
000 = 1 bit
R109 (6Dh)
Write
Sequencer 1
WSEQ_DATA
_WIDTH [2:0]
14:12
000
001 = 2 bits
010 = 3 bits
011 = 4 bits
100 = 5 bits
101 = 6 bits
110 = 7 bits
111 = 8 bits
Bit position of the LSB of the data block
written in this sequence step.
WSEQ_DATA
_START [3:0]
11:8
0000
0000 = Bit 0
…
1111 = Bit 15
WSEQ_ADDR
[7:0]
Control Register Address to be written to
in this sequence step.
7:0
14
0000_0000
0
R110 (6Eh)
Write
Sequencer 2
WSEQ_EOS
End of Sequence flag. This bit indicates
whether the Control Write Sequencer
should stop after executing this step.
0 = Not end of sequence
1 = End of sequence (Stop the
sequencer after this step).
WSEQ_DELA
Y [3:0]
Time delay after executing this step.
11:8
0000
Total time per step (including execution)
= 62.5µs × (2WSEQ_DELAY + 8)
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
WSEQ_DATA
[7:0]
Data to be written in this sequence step.
When the data width is less than 8 bits,
then one or more of the MSBs of
WSEQ_DATA are ignored. It is
recommended that unused bits be set to
0.
7:0
0000_0000
Table 77 Write Sequencer Control - Programming a Sequence
Note that a ‘Dummy’ write can be inserted into a control sequence by commanding the sequencer to
write a value of 0 to bit 0 of Register R255 (FFh). This is effectively a write to a non-existent register
location. This can be used in order to create placeholders ready for easy adaptation of the sequence.
For example, a sequence could be defined to power-up a mono signal path from DACL to
headphone, with a ‘dummy’ write included to leave space for easy modification to a stereo signal path
configuration. Dummy writes can also be used in order to implement additional time delays between
register writes. Dummy writes are included in the default start-up sequence – see Table 79.
In summary, the Control Register to be written is set by the WSEQ_ADDR field. The data bits that are
written are determined by a combination of WSEQ_DATA_START, WSEQ_DATA_WIDTH and
WSEQ_DATA. This is illustrated below for an example case of writing to the VMID_RES field within
Register R5 (05h).
In this example, the Start Position is bit 01 (WSEQ_DATA_START = 0001b) and the Data width is 2
bits (WSEQ_DATA_WIDTH = 0001b). With these settings, the Control Write Sequencer would
updated the Control Register R5 [2:1] with the contents of WSEQ_DATA [1:0].
LSB position = b01
WSEQ_DATA_STARTn = 0001
b15 b14 b13 b12 b11 b10 b09 b08 b07 b06 b05 b04 b03 b02 b01 b00
R5 (05h)
VMID Control 0
VMID_RES
Data Width = 2 bits
WSEQ_DATA_WIDTHn = 0001
b07 b06 b05 b04 b03 b02 b01 b00
WSEQ_DATAn (8 bits)
WSEQ_DATA_WIDTHn = 2 bits.
Therefore, only the Least Significant 2 bits are valid. Bits 02 to 07 are discarded
Figure 64 Control Write Sequencer Example
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DEFAULT SEQUENCES
When the WM8903 is powered up, two Control Write Sequences are available through default
settings in both RAM and ROM memory locations. The purpose of these sequences, and the register
write required to initiate them, is summarised in Table 78. In both cases, a single register write will
initiate the sequence.
WSEQ START
INDEX
WSEQ FINISH
INDEX
PURPOSE
TO INITIATE
Write 0100h to
Register R111 (6Fh)
Write 0120h to
0 (00h)
29 (1Dh)
48 (30h)
Start-Up sequence
Shutdown sequence
32 (20h)
Register R111 (6Fh)
Table 78 Write Sequencer Default Sequences
Note on Shut-Down sequence: The instruction at Index Address 32 (20h) shorts the outputs
LINEOUTL and LINEOUTR. If the Line outputs are not in use at the time the sequence is run, then
the sequence could, instead, be started at Index Address 33.
Index addresses 0 to 31 may be programmed to users’ own settings at any time, as described in
“Programming a Sequence” Users’ own settings remain in memory and are not affected by software
resets (i.e. writing to Register R0). However, any non-default sequences are lost when the device is
powered down.
START-UP SEQUENCE
The Start-up sequence is initiated by writing 0100h to Register R111 (6Fh). This single operation
starts the Control Write Sequencer at Index Address 0 (00h) and executes the sequence defined in
Table 79.
For typical clocking configurations with MCLK=12.288MHz, this sequence takes approximately 425ms
to run.
WSEQ
INDEX
REGISTER
ADDRESS
WIDTH
START
DATA
DELAY
EOS
DESCRIPTION
POBCTRL = 1
0 (00h)
R4 (04h)
5 bits
Bit 0
1Ah
0h
0b
ISEL [1:0] = 10b
STARTUP_BIAS_ENA = 1
BIAS_ENA = 0
(delay = 0.5625ms)
SPK_DISCHARGE = 1
(delay = 32.5ms)
1 (01h)
2 (02h)
R65 (41h)
R17 (11h)
1 bit
Bit 1
Bit 0
01h
03h
9h
0h
0b
0b
SPKL_ENA = 1
2 bits
SPKR_ENA = 1
(delay = 0.5625ms)
SPK_DISCHARGE = 0
(delay = 0.5625ms)
VMID_TIE_ENA = 1
BUFIO_ENA = 1
3 (03h)
4 (04h)
R65 (41h)
R5 (5h)
1 bit
Bit 1
Bit 0
00h
F7h
0h
Bh
0b
0b
8 bits
VMID_IO_ENA = 1
VMID_SOFT = 10
VMID_RES = 11
VMID_BUF_ENA = 1
(delay = 128.5ms)
SPKL_ENA = 0
5 (05h)
R17 (11h)
2 bits
Bit 0
00h
0h
0b
SPKR_ENA = 0
(delay = 0.5625ms)
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WSEQ
INDEX
REGISTER
ADDRESS
WIDTH
START
DATA
DELAY
EOS
DESCRIPTION
VMID_SOFT = 00
6 (06h)
7 (07h)
8 (08h)
9 (09h)
R5 (5h)
2 bits
Bit 3
00h
0h
0b
(delay = 0.5625ms)
VMID_RES [1:0] = 01b
(delay = 0.5625ms)
BIAS_ENA = 1
R5 (05h)
R4 (04h)
R14 (0Eh)
2 bits
1 bit
Bit 1
Bit 0
Bit 0
01h
01h
03h
0h
0h
0h
0b
0b
0b
(delay = 0.5625ms)
HPL_PGA_ENA = 1
HPR_PGA_ENA = 1
(delay = 0.5625ms)
MIXOUTL = 1
2 bits
10 (0Ah)
11 (0Bh)
R13 (Dh)
2 bits
2 bits
Bit 0
Bit 0
03h
03h
0h
0h
0b
0b
MIXOUTR = 1
(delay = 0.5625ms)
LINEOUTL_PGA_ENA = 1
LINEOUTR_PGA_ENA = 1
(delay = 0.5625ms)
CLK_DSP_ENA = 1
(delay = 0.5625ms)
DACL_ENA = 1
R15 (0Fh)
12 (0Ch)
13 (0Dh)
R22 (16h)
R18 (12h)
1 bit
Bit 1
Bit 2
01h
03h
0h
5h
0b
0b
2 bits
DACR_ENA = 1
(delay = 2.5ms)
Dummy Write for expansion
(delay = 0.5625ms)
POBCTRL = 0
14 (0Eh)
15 (0Fh)
16 (10h)
17 (11h)
18 (12h)
R255 (FFh)
R4 (04h)
1 bit
1 bit
1 bit
1 bit
8 bits
Bit 0
Bit 4
Bit 0
Bit 0
Bit 0
00h
00h
01h
00h
11h
0h
0h
6h
0h
0h
0b
0b
0b
0b
0b
(delay = 0.5625ms)
CP_ENA = 1
R98 (62h)
R255 (FFh)
R90 (5Ah)
(delay = 4.5ms)
Dummy Write for expansion
(delay = 0.5625ms)
HPL_ENA = 1
HPR_ENA = 1
(delay = 0.5625ms)
LINEOUTL_ENA = 1
LINEOUTR_ENA = 1
(delay = 0.5625ms)
HPL_ENA_DLY = 1
HPR_ENA_DLY = 1
(delay = 0.5625ms)
LINEOUTL_ENA_DLY = 1
LINEOUTR_ENA_DLY = 1
(delay = 0.5625ms)
DCS_MODE = 10
(delay = 0.5625ms)
DCS_ENA = 1111
(delay = 256.5ms)
DCS_ENA = 1111
(delay = 8.5ms)
19 (13h)
20 (14h)
21 (15h)
R94 (5Eh)
R90 (5Ah)
R94 (5Eh)
8 bits
8 bits
8 bits
Bit 0
Bit 0
Bit 0
11h
33h
33h
0h
0h
0h
0b
0b
0b
22 (16h)
23 (17h)
24 (18h)
25 (19h)
26 (1Ah)
R69 (45h)
R67 (43h)
R67 (43h)
R255 (FFh)
R90 (5Ah)
2 bits
4 bits
4 bits
1 bit
Bit 0
Bit 0
Bit 0
Bit 0
Bit 0
02h
0Fh
0Fh
00h
77h
0h
Ch
7h
0h
0h
0b
0b
0b
0b
0b
Dummy Write for expansion
(delay = 0.5625ms)
HPL_ENA_OUTP = 1
HPR_ENA_OUTP = 1
(delay = 0.5625ms)
8 bits
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WSEQ
INDEX
REGISTER
ADDRESS
WIDTH
START
DATA
DELAY
EOS
DESCRIPTION
LINEOUTL_ENA_OUTP = 1
LINEOUTR_ENA_OUTP = 1
(delay = 0.5625ms)
HPL_RMV_SHORT = 1
HPR_RMV_SHORT = 1
(delay = 0.5625ms)
LINEOUTL_RMV_SHORT = 1
LINEOUTR_RMV_SHORT = 1
End of Sequence
27 (1Bh)
28 (1Ch)
29 (1Dh)
R94 (5Eh)
8 bits
Bit 0
77h
0h
0b
R90 (5Ah)
R94 (5Eh)
8 bits
8 bits
Bit 0
Bit 0
FFh
FFh
0h
0h
0b
1b
Spare
30 (1Eh)
31 (1Fh)
R255 (FFh)
R255 (FFh)
1 bit
1 bit
Bit 0
Bit 0
00h
00h
0h
0h
0b
0b
Spare
Table 79 Start-up Sequence
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WM8903
SHUTDOWN SEQUENCE
The Shutdown sequence is initiated by writing 0120h to Register R111 (6Fh). This single operation
starts the Control Write Sequencer at Index Address 32 (20h) and executes the sequence defined in
Table 80.
For typical clocking configurations with MCLK=12.288MHz, this sequence takes approximately 325ms
to run.
WSEQ
INDEX
REGISTER
ADDRESS
WIDTH
START
DATA
DELAY
EOS
DESCRIPTION
LINEOUTL_RMV_SHORT = 0
LINEOUTR_RMV_SHORT = 0
(delay = 0.5625ms)
HPL_RMV_SHORT = 0
HPR_RMV_SHORT = 0
(delay = 0.5625ms)
HPL_ENA_OUTP = 0
HPL_ENA_DLY = 0
HPL_ENA = 0
32 (20h)
33 (21h)
34 (22h)
R94 (5Eh)
8 bits
Bit 0
77h
0h
0b
R90 (5Ah)
R90 (5Ah)
8 bits
8 bits
Bit 0
Bit 0
77h
00h
0h
0h
0b
0b
HPR_ENA_OUTP = 0
HPR_ENA_DLY = 0
HPR_ENA = 0
(delay = 0.5625ms)
LINEOUTL_ENA_OUTP = 0
LINEOUTL_ENA_DLY = 0
LINEOUTL_ENA = 0
LINEOUTR_ENA_OUTP = 0
LINEOUTR_ENA_DLY = 0
LINEOUTR_ENA = 0
(delay = 0.5625ms)
DCS_ENA = 0000
35 (23h)
R94 (5Eh)
8 bits
Bit 0
00h
0h
0b
36 (24h)
37 (25h)
38 (26h)
R67 (43h)
R98 (62h)
R18 (12h)
4 bits
1 bit
Bit 0
Bit 0
Bit 2
00h
00h
00h
0h
0h
0h
0b
0b
0b
(delay = 0.5625ms)
CP_ENA = 0
(delay = 0.5625ms)
DACL_ENA = 0
2 bits
DACR_ENA = 0
(delay = 0.5625ms)
CLK_DSP_ENA = 0
(delay = 0.5625ms)
HPL_PGA_ENA = 0
HPR_PGA_ENA = 0
(delay = 0.5625ms)
LINEOUTL_PGA_ENA = 0
LINEOUTR_PGA_ENA = 0
(delay = 0.5625ms)
MIXOUTL_ENA = 0
MIXOUTR_ENA = 0
(delay = 0.5625ms)
BIAS_ENA = 0
39 (27h)
40 (28h)
R22 (16h)
R14 (0Eh)
1 bit
Bit 1
Bit 0
00h
00h
0h
0h
0b
0b
2 bits
41 (29h)
42 (2Ah)
R15 (0Fh)
R13 (0Dh)
2 bits
2 bits
Bit 0
Bit 0
00h
00h
0h
0h
0b
0b
43 (2Bh)
44 (2Ch)
45 (2Dh)
46 (2Eh)
R4 (04h)
R5 (05h)
R5 (05h)
R5 (05h)
1 bit
2 bits
1 bit
1 bit
Bit 0
Bit 3
Bit 0
Bit 0
00h
02h
00h
00h
0h
0h
Ch
9h
0b
0b
0b
0b
(delay = 0.5625ms)
VMID_SOFT = 10
(delay = 0.5625ms)
VMID_BUF_ENA = 0
(delay = 256.5ms)
VMID_BUF_ENA = 0
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WSEQ
INDEX
REGISTER
ADDRESS
WIDTH
START
DATA
DELAY
EOS
DESCRIPTION
(delay = 32.5ms)
VMID_TIE_ENA = 0
BUFIO_ENA = 0
47 (2Fh)
R5 (05h)
8 bits
Bit 0
00h
0h
0b
VMID_IO_ENA = 0
VMID_SOFT = 00
VMID_RES = 00
VMID_BUF_ENA = 0
(delay = 0.5625ms)
STARTUP_BIAS_ENA = 0
BIAS_ENA = 0
48 (30h)
R4 (04h)
2 bits
Bit 0
00h
0h
1b
End of Sequence
Table 80 Shutdown Sequence
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WM8903
POWER-ON RESET
The WM8903 includes an internal Power-On-Reset (POR) circuit, which is used to reset the digital
logic into a default state after power up. The POR circuit is powered from AVDD and monitors
DCVDD. The internal P¯O¯¯R signal is asserted low when AVDD or DCVDD are below minimum
thresholds.
The specific behaviour of the circuit will vary, depending on the relative timing of the supply voltages.
Typical scenarios are illustrated in Figure 65 and Figure 66.
AVDD
Vpora
Vpora_off
0V
DCVDD
Vpord_on
0V
tpusetup
tpuhold
HI
ADDR/GPIO3
LO
HI
Internal POR
LO
POR active
POR active
Device ready
POR undefined
Figure 65 Power On Reset timing - AVDD enabled first
Figure 66 Power On Reset timing - DCVDD enabled first
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The P¯O¯¯R signal is undefined until AVDD has exceeded the minimum threshold, Vpora Once this
threshold has been exceeded, P¯O¯¯R is asserted low and the chip is held in reset. In this condition, all
writes to the control interface are ignored. Once AVDD and DCVDD have reached their respective
power on thresholds, P¯O¯¯R is released high, all registers are in their default state, and writes to the
control interface may take place.
Note that a minimum power-on reset period, TPOR, applies even if AVDD and DCVDD have zero rise
time. (This specification is guaranteed by design rather than test.)
On power down, P¯O¯¯R is asserted low when any of AVDD or DCVDD falls below their respective
power-down thresholds.
Typical Power-On Reset parameters for the WM8903 are defined in Table 81.
SYMBOL
Vpora
DESCRIPTION
AVDD threshold below which POR is undefined
Power-On threshold (AVDD)
TYP
0.5
UNIT
V
Vpora_on
Vpora_off
Vpord_on
Vpord_off
TPOR
1.15
1.12
0.57
0.56
10.6
V
Power-Off threshold (AVDD)
V
Power-On threshold (DCVDD)
Power-Off threshold (DCVDD)
Minimum Power-On Reset period
V
V
s
Table 81 Typical Power-On Reset Parameters
Notes:
1. If AVDD and DCVDD suffer a brown-out (i.e. drop below the minimum recommended operating
level but do not go below Vpora_off or Vpord_off) then the chip does not reset and resumes normal
operation when the voltage is back to the recommended level again.
2. The chip enters reset at power down when AVDD or DCVDD falls below Vpora_off or Vpord_off. This
may be important if the supply is turned on and off frequently by a power management system.
3. The minimum tpor period is maintained even if DCVDD and AVDD have zero rise time. This
specification is guaranteed by design rather than test.
4. See “Control Interface” section for details of tpusetup and tpuhold
.
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WM8903
QUICK START-UP AND SHUTDOWN
The WM8903 has the capability to perform a quick start-up and shut-down with a minimum number of
register operations. This is achieved using the Control Write Sequencer, which is configured with
default start-up settings that set up the device for DAC playback via Headphone and Line Output.
Assuming a 12.288MHz external clock, the start-up sequence configures the device for 48kHz
playback mode.
The default start-up sequence requires three register write operations. The default shutdown
sequence requires just a single register write. The minimum procedure for executing the quick start-
up and shutdown sequences is described below. See “Control Write Sequencer” for more details.
QUICK START-UP (DEFAULT SEQUENCE)
An external clock must be applied to MCLK. Assuming 12.288MHz input clock, the start-up sequence
will take approximately 425ms to complete.
The following register operations will initiate the quick start-up sequence.
REGISTER
ADDRESS
VALUE
DESCRIPTION
WSMD_CLK_ENA = 1
R108 (6Ch)
0100h
Write Sequencer 0
R22 (16h)
This enables the Write Sequencer Clock
CLK_SYS_ENA = 1
0004h
0100h
Clock Rates 2
R111 (6Fh)
This enables the System Clock
WSEQ_START_INDEX = 00h
WSEQ_START = 1
Write Sequencer 3
WSEQ_ABORT = 0
This starts the Write Sequencer at Index address 0 (00h)
Table 82 Quick Start-Up Control
The WSEQ_BUSY bit (in Register R112, see Table 76) will be set to 1 while the sequence runs.
When this bit returns to 0, the device has been set up and is ready for DAC playback operation.
QUICK SHUTDOWN (DEFAULT SEQUENCE)
The default shutdown sequence assumes the initial device conditions are as configured by the default
start-up sequence. Assuming 12.288MHz input clock, the shutdown sequence will take approximately
325ms to complete.
The following register operation will initiate the default shut-down sequence.
REGISTER
VALUE
DESCRIPTION
WSEQ_START_INDEX = 20h
ADDRESS
R111 (6Fh)
Write Sequencer 3
0120h
WSEQ_START = 1
WSEQ_ABORT = 0
This starts the Write Sequencer at Index address 32 (20h)
Table 83 Quick Shutdown Control
The WSEQ_BUSY bit (in Register R112, see Table 76) will be set to 1 while the sequence runs.
When this bit returns to 0, the system clock can be disabled (CLK_SYS_ENA=0) and MCLK can be
stopped.
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SOFTWARE RESET AND CHIP ID
A Software Reset can be commanded by writing to Register R0. This is a read-only register field and
the contents will not be affected by writing to this Register.
The Chip ID can be read back from Register R0. The Chip Revision ID can be read back from
Register 1, as described in Table 84.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R0 (00h)
15:0
SW_RST_DE
C_ID1 [15:0]
8903h
Writing to this register resets all registers
to their default state.
SW Reset
and ID
Reading from this register will indicate
Device ID 8903h.
R1 (01h)
3:0
CHIP_REV
[3:0]
0010b
Reading from this register will indicate
the Revision ID.
Revision
Number
(Read-Only Register)
Table 84 Software Reset and Chip ID
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REGISTER MAP
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REGISTER BITS BY ADDRESS
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R0 (00h)
SW Reset
and ID
Writing to this register resets all
registers to their default state.
15:0
SW_RST_DEV_ID1 1000_1001_0000_0011
[15:0]
Reading from this register will
indicate Device ID 8903h.
Register 00h SW Reset and ID
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R1 (01h)
Revision
Number
Reading from this register will indicate the Revision
ID.
3:0
CHIP_REV [3:0]
0010
(Read-Only Register)
Register 01h Revision Number
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R4 (04h)
Bias Control
0
Selects the bias current source for output
amplifiers and VMID buffer
4
POBCTRL
1
0 = Default bias
1 = Start-Up bias
Master Bias control
00 = Normal bias x 0.5
01 = Normal bias x 0.75
10 = Normal bias
3:2
ISEL [1:0]
10
11 = Normal bias x 1.5
Enables the Start-Up bias current generator
0 = Disabled
1
0
STARTUP_BIAS_ENA
BIAS_ENA
0
0
1 = Enabled
Enables the Normal bias current generator (for
all analogue functions)
0 = Disabled
1 = Enabled
Register 04h Bias Control 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R5 (05h)
VMID
Control 0
VMID buffer to Differential Lineouts
0 = Disabled
7
VMID_TIE_ENA
0
1 = Enabled
(only applies when relevant outputs are disabled, ie.
SPLK=0 or SPKR=0. Resistance is controlled by
VROI.)
VMID buffer to unused input and output pins.
0 = Disabled
6
5
BUFIO_ENA
0
0
1 = Enabled
Enables the Start-Up bias current generator
0 = Disabled
VMID_IO_ENA
1 = Enabled
(same functionality as STARTUP_BIAS_ENA)
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
VMID soft start enable / slew rate control
00 = Disabled
4:3
VMID_SOFT
[1:0]
00
01 = Fast soft start
10 = Nominal soft start
11 = Slow soft start
VMID Divider Enable and Select
00 = VMID disabled (for OFF mode)
01 = 2 x 50k divider (for normal operation)
10 = 2 x 250k divider (for low power standby)
11 = 2 x 5k divider (for fast start-up)
VMID Buffer Enable
2:1
VMID_RES [1:0]
VMID_BUF_ENA
00
0
0
0 = Disabled
1 = Enabled
Register 05h VMID Control 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R6 (06h) Mic
Bias Control
0
MICBIAS Current Detect Insertion Threshold
00 = 0.063mA
5:4
MICDET_THR [1:0]
00
01 = 0.26mA
10 = 0.45mA
11 = 0.635mA
Values are scaled with AVDD. Figures shown are
based on AVDD=1.8V.
MICBIAS Short Circuit Button Push Threshold
00 = 0.52mA
3:2
MICSHORT_THR
[1:0]
00
01 = 0.77mA
10 = 1.2mA
11 = 1.43mA
Values are scaled with AVDD. Figures shown are
based on AVDD=1.8V.
MICBIAS Current and Short Circuit Detect Enable
1
0
MICDET_ENA
MICBIAS_ENA
0
0
0 = disabled
1 = enabled
MICBIAS Enable
0 = disabled
1 = enabled
Register 06h Mic Bias Control 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R8 (08h)
Analogue
DAC 0
DAC Bias boost
0 = Disable
5
DAC_BIAS_BOOST
0
1 = Enable
When DAC Bias boost is enabled, the bias
selected by DACBIAS_SEL and
DACVMID_BIAS_SEL are both doubled.
DAC bias current select
00 = Normal bias
4:3
DACBIAS_SEL [1:0]
00
01 = Normal bias x 0.5
10 = Normal bias x 0.66
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
11 = Normal bias x 0.75
DAC VMID buffer bias select
00 = Normal bias
2:1
DACVMID_BIAS_SEL
[1:0]
00
01 = Normal bias x 0.5
10 = Normal bias x 0.66
11 = Normal bias x 0.75
Register 08h Analogue DAC 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R10 (0Ah)
Analogue
ADC 0
ADC Oversampling Ratio
0 = Low Power (64 x fs)
0
ADC_OSR128
1
1 = High Performance (128 x fs)
Note that the Low Power options is not
supported when CLK_SYS_MODE=10
Register 10h Analogue ADC 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R12 (0Ch)
Power
Management
0
Left Input PGA Enable
1
INL_ENA
0
0
0 = disabled
1 = enabled
Right Input PGA Enable
0 = disabled
0
INR_ENA
1 = enabled
Register 0Ch Power Management 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R13 (0Dh)
Power
Left Output Mixer Enable
0 = disabled
1
MIXOUTL_ENA
0
Management
1
1 = enabled
Right Output Mixer Enable
0 = disabled
0
MIXOUTR_ENA
0
1 = enabled
Register 0Dh Power Management 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R14 (0Eh)
Power
Left Headphone Output Enable
0 = disabled
1
HPL_PGA_ENA
0
Management
2
1 = enabled
Right Headphone Output Enable
0 = disabled
0
HPR_PGA_ENA
0
1 = enabled
Register 0Eh Power Management 2
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Left Line Output Enable
R15 (0Fh)
Power
1
LINEOUTL_PGA_ENA
0
0 = disabled
Management
3
1 = enabled
Right Line Output Enable
0 = disabled
0
LINEOUTR_PGA_ENA
0
1 = enabled
Register 0Fh Power Management 3
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R16 (10h)
Power
Left Speaker Mixer Enable
0 = disabled
1
MIXSPKL_ENA
0
Management
4
1 = enabled
Right Speaker Mixer Enable
0 = disabled
0
MIXSPKR_ENA
0
1 = enabled
Register 10h Power Management 4
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R17 (11h)
Power
Left Speaker Output Enable
0 = disabled
1
SPKL_ENA
0
Management
5
1 = enabled
Right Speaker Output Enable
0 = disabled
0
SPKR_ENA
0
1 = enabled
Register 11h Power Management 5
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R18 (12h)
Power
Management
6
Left DAC Enable
0 = DAC disabled
1 = DAC enabled
Right DAC Enable
0 = DAC disabled
1 = DAC enabled
Left ADC Enable
0 = disabled
3
DACL_ENA
0
2
1
0
DACR_ENA
ADCL_ENA
ADCR_ENA
0
0
0
1 = enabled
Right ADC Enable
0 = disabled
1 = enabled
Register 12h Power Management 6
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Enables divide by 2 on MCLK
R20 (14h)
Clock Rates
0
0
MCLKDIV2
0
0 = CLK_SYS = MCLK
1 = CLK_SYS = MCLK / 2
Register 14h Clock Rates 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R21 (15h)
Clock Rates
1
CLK_SRC_SEL
SYSCLK Source Select
0 = MCLK
15
0
1 = FLL output
CLK_SYS / Sample rate (fs) ratio
13:10 CLK_SYS_RATE [3:0]
0011
if CLK_SYS_MODE = 00 (256*fs related clocks)
0000 = 64*fs
0001 = 128*fs
0010 = 192*fs
0011 = 256*fs
0100 = 384*fs
0101 = 512*fs
0110 = 768*fs
0111 = 1024 *fs
1000 = 1408*fs
1001 = 1536*fs
1010 to 1111 = Reserved
if CLK_SYS_MODE = 01 (272*fs related clocks)
0000 = 68*fs
0001 = 136*fs
0010 = 204*fs
0011 = 272*fs
0100 = 408*fs
0101 = 544*fs
0110 = 816*fs
0111 = 1088 *fs
1000 = 1496*fs
1001 = 1632*fs
1010 to 1111 = Reserved
if CLK_SYS_MODE = 10 (250*fs related clocks)
0000 = 125*fs
0001 = 125*fs
0010 = 250*fs
0011 = 250*fs
0100 = 375*fs
0101 = 500*fs
0110 = 750*fs
0111 = 1000 *fs
1000 = 1000*fs
1001 = 1500*fs
1010 to 1111 = Reserved
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
CLK_SYS mode
9:8
CLK_SYS_MODE
[1:0]
00
00 = 256*fs related
01 = 272*fs related
10 = 250*fs related
11 = Reserved
Selects the Sample Rate (fs)
0000 = 8kHz
3:0
SAMPLE_RATE [3:0]
1000
0001 = 11.025kHz
0010 = 12kHz
0011 = 16kHz
0100 = 22.05kHz
0101 = 24kHz
0110 = 32kHz
0111 = 44.1kHz
1000 = 48kHz
1001 = 88.2kHz (Not available for Digital
Microphone. Not used for 88.2kHz ADC.)
1010 = 96kHz (Not available for Digital
Microphone. Not used for 96kHz ADC).
1011 to 1111 = Reserved
If the desired sample rate is not listed in this
table, then the closest alternative should be
chosen.
Register 15h Clock Rates 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R22 (16h)
Clock Rates
2
System Clock enable
2
CLK_SYS_ENA
0
0
0
0 = Disabled
1 = Enabled
DSP Clock enable
0 = Disabled
1
0
CLK_DSP_ENA
TO_ENA
1 = Enabled
Zero Cross timeout enable
0 = Disabled
1 = Enabled
Register 16h Clock Rates 2
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R24 (18h)
Audio
Interface 0
Left DAC Invert
12
DACL_DATINV
0
0 = Left DAC output not inverted
1 = Left DAC output inverted
Right DAC Invert
11
DACR_DATINV
0
0 = Right DAC output not inverted
1 = Right DAC output inverted
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
DAC Digital Input Volume Boost
00 = 0dB
10:9
DAC_BOOST [1:0]
00
01 = +6dB (Input data must not exceed -6dBFS)
10 = +12dB (Input data must not exceed -12dBFS)
11 = +18dB (Input data must not exceed -18dBFS)
Digital Loopback Function
8
LOOPBACK
0
0 = No loopback
1 = Loopback enabled (ADC data output is directly
input to DAC data input)
Left Digital Audio channel source
7
6
5
4
AIFADCL_SRC
AIFADCR_SRC
AIFDACL_SRC
AIFDACR_SRC
0
1
0
1
0 = Left ADC data is output on left channel
1 = Right ADC data is output on left channel
Right Digital Audio channel source
0 = Left ADC data is output on right channel
1 = Right ADC data is output on right channel
Left DAC Data Source Select
0 = Left DAC outputs left channel data
1 = Left DAC outputs right channel data
Right DAC Data Source Select
0 = Right DAC outputs left channel data
1 = Right DAC outputs right channel data
ADC Companding Enable
0 = disabled
3
2
1
0
ADC_COMP
ADC_COMPMODE
DAC_COMP
0
0
0
0
1 = enabled
ADC Companding Type
0 = µ-law
1 = A-law
DAC Companding Enable
0 = disabled
1 = enabled
DAC Companding Type
0 = µ-law
DAC_COMPMODE
1 = A-law
Register 18h Audio Interface 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R25 (19h)
Audio
Interface 1
DAC TDM Enable
13
AIFDAC_TDM
0
0 = Normal DACDAT operation
1 = TDM enabled on DACDAT
DACDAT TDM Channel Select
0 = DACDAT data input on slot 0
1 = DACDAT data input on slot 1
ADC TDM Enable
12
11
10
AIFDAC_TDM_CHAN
AIFADC_TDM
0
0
0
0 = Normal ADCDAT operation
1 = TDM enabled on ADCDAT
ADCDAT TDM Channel Select
0 = ADCDAT outputs data on slot 0
1 = ADCDAT output data on slot 1
AIFADC_TDM_CHAN
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Audio Interface LRC Direction
0 = LRC is input
9
LRCLK_DIR
0
1 = LRC is output
BCLK Invert
7
6
4
AIF_BCLK_INV
BCLK_DIR
0
0
0
0 = BCLK not inverted
1 = BCLK inverted
Audio Interface BCLK Direction
0 = BCLK is input
1 = BCLK is output
LRC Polarity / DSP Mode A-B select.
AIF_LRCLK_INV
Right, left and I2S modes – LRC polarity
0 = Not Inverted
1 = Inverted
DSP Mode – Mode A-B select
0 = MSB is available on 2nd BCLK rising edge
after LRC rising edge (mode A)
1 = MSB is available on 1st BCLK rising edge
after LRC rising edge (mode B)
Digital Audio Interface Word Length
00 = 16 bits
3:2
1:0
AIF_WL [1:0]
AIF_FMT [1:0]
00
10
01 = 20 bits
10 = 24 bits
11 = 32 bits
Digital Audio Interface Format
00 = Right Justified
01 = Left Justified
10 = I2S
11 = DSP
Register 19h Audio Interface 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R26 (1Ah)
Audio
Interface 2
BCLK Frequency (Master Mode)
00000 = CLK_SYS
4:0
BCLK_DIV [4:0]
0_1000
00001 = Reserved
00010 = CLK_SYS / 2
00011 = CLK_SYS / 3
00100 = CLK_SYS / 4
00101 = CLK_SYS / 5
00110 = Reserved
00111 = CLK_SYS / 6
01000 = CLK_SYS / 8 (default)
01001 = CLK_SYS / 10
01010 = Reserved
01011 = CLK_SYS / 12
01100 = CLK_SYS / 16
01101 = CLK_SYS / 20
01110 = CLK_SYS / 22
01111 = CLK_SYS / 24
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
10000 = Reserved
10001 = CLK_SYS / 30
10010 = CLK_SYS / 32
10011 = CLK_SYS / 44
10100 = CLK_SYS / 48
Register 1Ah Audio Interface 2
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
LRC Rate (Master Mode)
R27 (1Bh)
Audio
Interface 3
10:0
LRCLK_RATE
[10:0]
000_0010_0010
LRC clock output = BCLK / LRCLK_RATE
Integer (LSB = 1)
Valid range: 8 to 2047
50:50 LRCLK duty cycle is only guaranteed with
even values (8, 10, … 2046).
Register 1Bh Audio Interface 3
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R30 (1Eh)
DAC Volume Update
8
DACVU
0
DAC Digital
Volume Left
Writing a 1 to this bit causes left and right DAC
volume to be updated simultaneously
(Write-Only Register)
Left DAC Digital Volume
00h = Mute
7:0
DACL_VOL
[7:0]
1100_0000
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h to FFh = 0dB
Register 1Eh DAC Digital Volume Left
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R31 (1Fh)
DAC Volume Update
8
DACVU
0
DAC Digital
Volume Right
Writing a 1 to this bit causes left and right DAC
volume to be updated simultaneously
(Write-Only Register)
Right DAC Digital Volume
00h = Mute
7:0
DACR_VOL
[7:0]
1100_0000
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h to FFh = 0dB
Register 1Fh DAC Digital Volume Right
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R32 (20h)
DAC Digital
0
Left Digital Sidetone Volume
0000 = -36dB
11:8
ADCL_DAC_SVOL
[3:0]
0000
0001 = -33dB
(… 3dB steps)
1011 = -3dB
11XX = 0dB
Right Digital Sidetone Volume
0000 = -36dB
7:4
ADCR_DAC_SVOL
[3:0]
0000
0001 = -33dB
(… 3dB steps)
1011 = -3dB
11XX = 0dB
Left DAC Digital Sidetone Source
00 = No sidetone
01 = Left ADC
3:2
1:0
ADC_TO_DACL [1:0]
ADC_TO_DACR [1:0]
00
00
10 = Right ADC
11 = Reserved
Right DAC Digital Sidetone Source
00 = No sidetone
01 = Left ADC
10 = Right ADC
11 = Reserved
Register 20h DAC Digital 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R33 (21h)
DAC Digital
1
DAC Mono Mix
0 = Stereo
12
DAC_MONO
0
0
1 = Mono (Mono mix output on enabled DAC)
Selects DAC filter characteristics
0 = Normal mode
11
10
DAC_SB_FILT
1 = Sloping stopband mode (recommended when fs
24kHz
DAC Soft Mute Ramp Rate
DAC_MUTERATE
0
0
0 = Fast ramp (fs/2, maximum ramp time is 10.7ms
at fs=48k)
1 = Slow ramp (fs/32, maximum ramp time is
171ms at fs=48k)
DAC Soft Mute Mode
9
DAC_MUTEMODE
0 = Disabling soft-mute (DAC_MUTE=0) will cause
the DAC volume to change immediately to
DACL_VOL and DACR_VOL settings
1 = Disabling soft-mute (DAC_MUTE=0) will cause
the DAC volume to ramp up gradually to the
DACL_VOL and DACR_VOL settings
DAC Soft Mute Control
0 = DAC Un-mute
3
DAC_MUTE
0
1 = DAC Mute
DAC De-Emphasis Control
00 = No de-emphasis
01 = 32kHz sample rate
10 = 44.1kHz sample rate
2:1
DEEMPH [1:0]
00
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
11 = 48kHz sample rate
DAC Oversampling Control
0
DAC_OSR
0
0 = Low power (normal oversample)
1 = High performance (double rate)
Register 21h DAC Digital 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R36 (24h)
ADC Volume Update
8
ADCVU
0
ADC Digital
Volume Left
Writing a 1 to this bit causes left and right ADC
volume to be updated simultaneously
(Write-Only Register)
Left ADC Digital Volume
00h = Mute
7:0
ADCL_VOL
[7:0]
1100_0000
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h = 0dB
… (0.375dB steps)
EFh = +17.625dB
F0h to FFh = +17.625dB
Register 24h ADC Digital Volume Left
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R37 (25h)
ADC Volume Update
8
ADCVU
0
ADC Digital
Volume Right
Writing a 1 to this bit causes left and right ADC
volume to be updated simultaneously
(Write-Only Register)
Right ADC Digital Volume
00h = Mute
7:0
ADCR_VOL
[7:0]
1100_0000
01h = -71.625dB
02h = -71.250dB
… (0.375dB steps)
C0h = 0dB
… (0.375dB steps)
EFh = +17.625dB
F0h to FFh = +17.625dB
Register 25h ADC Digital Volume Right
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R38 (26h)
ADC Digital
0
ADC Digital High Pass Filter Cut-Off Frequency
(fc)
6:5
ADC_HPF_CUT
[1:0]
00
00 = Hi-fi mode (fc=4Hz at fs=48kHz)
01 = Voice mode 1 (fc=127Hz at fs=16kHz)
10 = Voice mode 2 (fc=130Hz at fs=8kHz)
11 = Voice mode 3 (fc=267Hz at fs=8kHz)
(Note: fc scales with sample rate fs.)
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
ADC Digital High Pass Filter Enable
0 = disabled
4
ADC_HPF_ENA
0
1 = enabled
Left ADC Invert
1
0
ADCL_DATINV
ADCR_DATINV
0
0
0 = Left ADC output not inverted
1 = Left ADC output inverted
Right ADC Invert
0 = Right ADC output not inverted
1 = Right ADC output inverted
Register 26h ADC Digital 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R40 (28h)
DRC 0
DRC enable
1 = enabled
0 = disabled
15
DRC_ENA
0
Gain smoothing hysteresis threshold
00 = Low
12:11 DRC_THRESH_HYST [1:0]
01
01 = Medium (recommended)
10 = High
11 = Reserved
Initial gain at DRC startup
00000 = -18dB
10:6
DRC_STARTUP_GAIN
[4:0]
0_0110
00001 = -15dB
00010 = -12dB
00011 = -9dB
00100 = -6dB
00101 = -3dB
00110 = 0dB (default)
00111 = 3dB
01000 = 6dB
01001 = 9dB
01010 = 12dB
01011 = 15dB
01100 = 18dB
01101 = 21dB
01110 = 24dB
01111 = 27dB
10000 = 30dB
10001 = 33dB
10010 = 36dB
10011 to 11111 = Reserved
Feed-forward delay for anti-clip feature
0 = 5 samples
5
3
DRC_FF_DELAY
1
1
1 = 9 samples
Time delay can be calculated as 5/fs or 9/ fs,
where fs is the sample rate.
Gain smoothing enable
0 = disabled
DRC_SMOOTH_ENA
1 = enabled
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Production Data
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Quick release enable
2
DRC_QR_ENA
1
0 = disabled
1 = enabled
Anti-clip enable
0 = disabled
1
0
DRC_ANTICLIP_ENA
DRC_HYST_ENA
1
1
1 = enabled
Gain smoothing hysteresis enable
0 = disabled
1 = enabled
Register 28h DRC 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R41 (29h)
DRC 1
Gain attack rate (seconds/6dB)
15:12
DRC_ATTACK_RATE
[3:0]
0011
0000 = Reserved
0001 = 182µs
0010 = 363µs
0011 = 726µs (default)
0100 = 1.45ms
0101 = 2.9ms
0110 = 5.8ms
0111 = 11.6ms
1000 = 23.2ms
1001 = 46.4ms
1010 = 92.8ms
1011-1111 = Reserved
Gain decay rate (seconds/6dB)
0000 = 186ms
11:8 DRC_DECAY_RATE [3:0]
0010
0001 = 372ms
0010 = 743ms (default)
0011 = 1.49s
0100 = 2.97s
0101 = 5.94s
0110 = 11.89s
0111 = 23.78s
1000 = 47.56s
1001-1111 = Reserved
Quick release crest factor threshold
00 = 12dB
7:6
5:4
DRC_THRESH_QR [1:0]
DRC_RATE_QR [1:0]
01
00
01 = 18dB (default)
10 = 24dB
11 = 30dB
Quick release decay rate (seconds/6dB)
00 = 0.725ms (default)
01 = 1.45ms
10 = 5.8ms
11 = Reserved
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Minimum gain the DRC can use to attenuate
audio signals
3:2
DRC_MINGAIN [1:0]
00
00 = 0dB (default)
01 = -6dB
10 = -12dB
11 = -18dB
Maximum gain the DRC can use to boost
audio signals
1:0
DRC_MAXGAIN [1:0]
01
00 = 12dB
01 = 18dB (default)
10 = 24dB
11 = 36dB
Register 29h DRC 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
100
DESCRIPTION
Compressor slope R0
R42 (2Ah)
DRC 2
5:3
DRC_R0_SLOPE_COMP
[2:0]
000 = 1 (no compression)
001 = 1/2
010 = 1/4
011 = 1/8
100 = 1/16
101 = 0
110 = Reserved
111 = Reserved
Compressor slope R1
000 = 1 (no compression)
001 = 1/2
2:0
DRC_R1_SLOPE_COMP
[2:0]
000
010 = 1/4
011 = 1/8
100 = 0
101 = Reserved
11X = Reserved
Register 2Ah DRC 2
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R43 (2Bh)
DRC 3
Compressor threshold T (dB)
000000 = 0dB
10:5
DRC_THRESH_COMP
[5:0]
00_0000
000001 = -0.75dB
000010 = -1.5dB
… (-0.75dB steps)
111100 = -45dB
111101 = Reserved
11111X = Reserved
Compressor amplitude at threshold YT (dB)
00000 = 0dB
4:0
DRC_AMP_COMP [4:0]
0_0000
00001 = -0.75dB
00010 = -1.5dB
… (-0.75dB steps)
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
11110 = -22.5dB
11111 = Reserved
Register 2Bh DRC 3
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Left Input PGA Mute
R44 (2Ch)
Analogue
Left Input 0
7
LINMUTE
1
0 = not muted
1 = muted
Left Input PGA Volume
4:0
LIN_VOL [4:0]
0_0101
If L_MODE = 00 (Single ended)
OR L_MODE = 01 (Differential Line)
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
-1.55
-1.3
-1.0
-0.7
-0.3
+0.0 (default)
+0.3
+0.7
+1.0
+1.4
+1.8
+2.3
+2.7
+3.2
+3.7
+4.2
+4.8
+5.4
+6.0
+6.7
+7.5
+8.3
+9.2
+10.2
+11.4
+12.7
+14.3
+16.2
+19.2
+22.3
+25.2
+28.3
If L_MODE = 1X (Differential MIC)
00000
00001
00010
00011
Not valid
+12
+15
+18
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
00100
+21
+24
+27
+30
+30
+30
00101 (default)
00110
00111
01XXX
1XXXX
Register 2Ch Analogue Left Input 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R45 (2Dh)
Analogue
Right Input 0
Right Input PGA Mute
0 = not muted
7
RINMUTE
1
1 = muted
Right Input PGA Volume
4:0
RIN_VOL [4:0]
0_0101
If R_MODE = 00 (Single ended)
OR R_MODE = 01 (Differential Line)
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
-1.55
-1.3
-1.0
-0.7
-0.3
+0.0 (default)
+0.3
+0.7
+1.0
+1.4
+1.8
+2.3
+2.7
+3.2
+3.7
+4.2
+4.8
+5.4
+6.0
+6.7
+7.5
+8.3
+9.2
+10.2
+11.4
+12.7
+14.3
+16.2
+19.2
+22.3
+25.2
+28.3
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Production Data
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
If R_MODE = 1X (Differential MIC)
00000
Not valid
+12
00001
00010
+15
00011
+18
00100
+21
00101 (default)
00110
+24
+27
00111
+30
01XXX
1XXXX
+30
+30
Register 2Dh Analogue Right Input 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R46 (2Eh)
Analogue
Left Input 1
Left Input PGA Common Mode Rejection enable
0 = Disabled
6
INL_CM_ENA
1
1 = Enabled
(only available for L_MODE=01 – Differential Line)
In Single-Ended or Differential Line Modes, this field
selects the input pin for the inverting side of the left
input path.
5:4
3:2
1:0
L_IP_SEL_N
[1:0]
00
01
00
In Differential Mic Mode, this field selects the input
pin for the non-inverting side of the left input path.
00 = IN1L
01 = IN2L
1X = IN3L
In Single-Ended or Differential Line Modes, this field
selects the input pin for the non-inverting side of the
left input path.
L_IP_SEL_P
[1:0]
In Differential Mic Mode, this field selects the input
pin for the inverting side of the left input path.
00 = IN1L
01 = IN2L
1X = IN3L
Sets the mode for the left analogue input:
00 = Single-Ended
01 = Differential Line
10 = Differential MIC
11 = Reserved
L_MODE [1:0]
Register 2Eh Analogue Left Input 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R47 (2Fh)
Analogue
Right Input 1
Right Input PGA Common Mode Rejection enable
0 = Disabled
6
INR_CM_ENA
1
1 = Enabled
(only available for R_MODE=01 – Differential Line)
In Single-Ended or Differential Line Modes, this field
selects the input pin for the inverting side of the right
input path.
5:4
R_IP_SEL_N
[1:0]
00
In Differential Mic Mode, this field selects the input
pin for the non-inverting side of the right input path.
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
00 = IN1R
01 = IN2R
1X = IN3R
In Single-Ended or Differential Line Modes, this field
selects the input pin for the non-inverting side of the
right input path.
3:2
R_IP_SEL_P
[1:0]
01
In Differential Mic Mode, this field selects the input
pin for the inverting side of the right input path.
00 = IN1R
01 = IN2R
1X = IN3R
Sets the mode for the right analogue input:
00 = Single-Ended
01 = Differential Line
10 = Differential MIC
11 = Reserved
1:0
R_MODE [1:0]
00
Register 2Fh Analogue Right Input 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R50 (32h)
Analogue
Left Mix 0
Left DAC to Left Output Mixer Enable
0 = disabled
3
DACL_TO_MIXOUTL
DACR_TO_MIXOUTL
BYPASSL_TO_MIXOUTL
1
0
0
1 = enabled
Right DAC to Left Output Mixer Enable
0 = disabled
2
1
1 = enabled
Left Analogue Input to Left Output Mixer
Enable
0 = disabled
1 = enabled
Right Analogue Input to Left Output Mixer
Enable
0
BYPASSR_TO_MIXOUTL
0
0 = disabled
1 = enabled
Register 32h Analogue Left Mix 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R51 (33h)
Analogue
Right Mix 0
Left DAC to Right Output Mixer Enable
0 = disabled
3
DACL_TO_MIXOUTR
0
1 = enabled
Right DAC to Right Output Mixer Enable
0 = disabled
2
1
DACR_TO_MIXOUTR
1
0
1 = enabled
Left Analogue Input to Right Output Mixer
Enable
BYPASSL_TO_MIXOUTR
0 = disabled
1 = enabled
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Right Analogue Input to Right Output Mixer
Enable
0
BYPASSR_TO_MIXOUTR
0
0 = disabled
1 = enabled
Register 33h Analogue Right Mix 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R52 (34h)
Analogue
Spk Mix Left
0
Left DAC to Left Spkr Mixer Enable
0 = disabled
3
DACL_TO_MIXSPKL
0
1 = enabled
Right DAC to Left Spkr Mixer Enable
0 = disabled
2
1
0
DACR_TO_MIXSPKL
BYPASSL_TO_MIXSPKL
BYPASSR_TO_MIXSPKL
0
0
0
1 = enabled
Left Analogue Input to Left Spkr Mixer Enable
0 = disabled
1 = enabled
Right Analogue Input to Left Spkr Mixer
Enable
0 = disabled
1 = enabled
Register 34h Analogue Spk Mix Left 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R53 (35h)
Analogue
Spk Mix Left
1
Left DAC to Left Spkr Mixer volume control
3
DACL_MIXSPKL_VOL
0
0 = 0dB
1 = -6dB
Right DAC to Left Spkr Mixer volume control
2
1
DACR_MIXSPKL_VOL
0
0
0 = 0dB
1 = -6dB
Left Analogue Input to Left Spkr Mixer volume
control
BYPASSL_MIXSPKL_VOL
0 = 0dB
1 = -6dB
Right Analogue Input to Left Spkr Mixer
volume control
0
BYPASSR_MIXSPKL_VOL
0
0 = 0dB
1 = -6dB
Register 35h Analogue Spk Mix Left 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R54 (36h)
Analogue
Spk Mix
Right 0
Left DAC to Right Spkr Mixer Enable
0 = disabled
3
DACL_TO_MIXSPKR
0
1 = enabled
Right DAC to Right Spkr Mixer Enable
0 = disabled
2
DACR_TO_MIXSPKR
0
1 = enabled
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Left Analogue Input to Right Spkr Mixer
Enable
1
BYPASSL_TO_MIXSPKR
0
0 = disabled
1 = enabled
Right Analogue Input to Right Spkr Mixer
Enable
0
BYPASSR_TO_MIXSPKR
0
0 = disabled
1 = enabled
Register 36h Analogue Spk Mix Right 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R55 (37h)
Analogue
Spk Mix
Right 1
Left DAC to Right Spkr Mixer volume control
3
DACL_MIXSPKR_VOL
0
0 = 0dB
1 = -6dB
Right DAC to Right Spkr Mixer volume
control
2
1
0
DACR_MIXSPKR_VOL
BYPASSL_MIXSPKR_VOL
BYPASSR_MIXSPKR_VOL
0
0
0
0 = 0dB
1 = -6dB
Left Analogue Input to Right Spkr Mixer
volume control
0 = 0dB
1 = -6dB
Right Analogue Input to Right Spkr Mixer
volume control
0 = 0dB
1 = -6dB
Register 37h Analogue Spk Mix Right 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R57 (39h)
Analogue
OUT1 Left
Left Headphone Output Mute
0 = Un-mute
8
HPL_MUTE
0
1 = Mute
Headphone Output Volume Update
7
HPOUTVU
0
Writing a 1 to this bit will update HPOUTL and
HPOUTR volumes simultaneously.
(Write-Only Register)
Left Headphone Output Zero Cross Enable
0 = disabled
6
HPOUTLZC
0
1 = enabled
Left Headphone Output Volume
000000 = -57dB
5:0
HPOUTL_VOL
[5:0]
10_1101
000001 = -56dB
(… 1dB steps)
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Register 39h Analogue OUT1 Left
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R58 (3Ah)
Analogue
OUT1 Right
Right Headphone Output Mute
0 = Un-mute
8
HPR_MUTE
0
1 = Mute
Headphone Output Volume Update
7
HPOUTVU
0
Writing a 1 to this bit will update HPOUTL and
HPOUTR volumes simultaneously.
(Write-Only Register)
Right Headphone Output Zero Cross Enable
0 = disabled
6
HPOUTRZC
0
1 = enabled
Right Headphone Output Volume
000000 = -57dB
5:0
HPOUTR_VOL
[5:0]
10_1101
000001 = -56dB
(… 1dB steps)
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Register 3Ah Analogue OUT1 Right
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R59 (3Bh)
Analogue
OUT2 Left
Left Line Output Mute
0 = Un-mute
8
LINEOUTL_MUTE
0
1 = Mute
Line Output Volume Update
7
LINEOUTVU
LINEOUTLZC
0
Writing a 1 to this bit will update LINEOUTL and
LINEOUTR volumes simultaneously.
(Write-Only Register)
Left Line Output Zero Cross Enable
0 = disabled
6
0
1 = enabled
Left Line Output Volume
000000 = -57dB
000001 = -56dB
(… 1dB steps)
5:0
LINEOUTL_VOL
[5:0]
11_1001
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Register 3Bh Analogue OUT2 Left
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Right Line Output Mute
R60 (3Ch)
Analogue
OUT2 Right
8
LINEOUTR_MUTE
0
0 = Un-mute
1 = Mute
Line Output Volume Update
7
LINEOUTVU
0
Writing a 1 to this bit will update LINEOUTL and
LINEOUTR volumes simultaneously.
(Write-Only Register)
Right Line Output Zero Cross Enable
0 = disabled
6
LINEOUTRZC
0
1 = enabled
Right Line Output Volume
000000 = -57dB
5:0
LINEOUTR_VOL
[5:0]
11_1001
000001 = -56dB
(… 1dB steps)
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Register 3Ch Analogue OUT2 Right
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R62 (3Eh)
Analogue
OUT3 Left
Left Speaker Output Mute
0 = Un-mute
8
SPKL_MUTE
1
1 = Mute
Speaker Output Volume Update
7
SPKVU
0
Writing a 1 to this bit will update LON/LOP and
RON/ROP volumes simultaneously.
(Write-Only Register)
Left Speaker Output Zero Cross Enable
0 = disabled
6
SPKLZC
0
1 = enabled
Left Speaker Output Volume
000000 = -57dB
5:0
SPKL_VOL
[5:0]
11_1001
000001 = -56dB
(… 1dB steps)
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Register 3Eh Analogue OUT3 Left
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Right Speaker Output Mute
R63 (3Fh)
Analogue
OUT3 Right
8
SPKR_MUTE
1
0 = Un-mute
1 = Mute
Speaker Output Volume Update
7
SPKVU
0
Writing a 1 to this bit will update LON/LOP and
RON/ROP volumes simultaneously.
(Write-Only Register)
Right Speaker Output Zero Cross Enable
0 = disabled
6
SPKRZC
0
1 = enabled
Right Speaker Output Volume
000000 = -57dB
5:0
SPKR_VOL
[5:0]
11_1001
000001 = -56dB
(… 1dB steps)
111001 = 0dB
(… 1dB steps)
111110 = +5dB
111111 = +6dB
Register 3Fh Analogue OUT3 Right
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R65 (41h)
Analogue
SPK Output
Control 0
Speaker Discharge Enable
0 = Disabled
1
SPK_DISCHARGE
0
1 = Enable
Select VMID_TIE_ENA resistance for disabled
Differential Lineouts
0
VROI
0
0 = 20k ohm
1 = 500 ohm
Register 41h Analogue SPK Output Control 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
DC Servo Master Control
R67 (43h)
4
DCS_MASTER_ENA
1
DC Servo 0
0 = DC Servo Reset
1 = DC Servo Enabled
DC Servo Enable
3:0
DCS_ENA [3:0]
0000
[3] - HPOUTL enable
[2] - HPOUTR enable
[1] - LINEOUTL enable
[0] - LINEOUTR enable
Register 43h DC Servo 0
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R69 (45h)
DC Servo 2
DC Servo Mode
1:0
DCS_MODE
[1:0]
00
00 = WRITE_STOP
01 = WRITE_UPDATE
10 = START_STOP
11 = START_UPDATE
Register 45h DC Servo 2
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R71 (47h)
DC Servo 4
DCS_HPOUTL_WRITE_VAL
[7:0]
Value to send to Left Headphone Output
Servo in a WRITE mode
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
Register 47h DC Servo 4
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R72 (48h)
DC Servo 5
DCS_HPOUTR_WRITE_VAL
[7:0]
Value to send to Right Headphone Output
Servo in a WRITE mode
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
Register 48h DC Servo 5
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R73 (49h)
DC Servo 6
DCS_LOUTL_WRITE_VAL
[7:0]
Value to send to Left Line Output Servo in a
WRITE mode
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
Register 49h DC Servo 6
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R74 (4Ah)
DC Servo 7
DCS_LOUTR_WRITE_VAL
[7:0]
Value to send to Right Line Output Servo in a
WRITE mode
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
Register 4Ah DC Servo 7
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Production Data
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R81 (51h)
DC Servo
Readback 1
DCS_HPOUTL_INTEG [7:0]
Readback value on Left Headphone Output
Servo.
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
(Read-Only Register)
Register 51h DC Servo Readback 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R82 (52h)
DC Servo
Readback 2
DCS_HPOUTR_INTEG [7:0]
Readback value on Right Headphone
Output Servo.
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
(Read-Only Register)
Register 52h DC Servo Readback 2
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R83 (53h)
DC Servo
Readback 3
DCS_LOUTL_INTEG [7:0]
Readback value on Left Line Output Servo.
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
(Read-Only Register)
Register 53h DC Servo Readback 3
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R84 (54h)
DC Servo
Readback 4
DCS_LOUTR_INTEG [7:0]
Readback value on Right Line Output
Servo.
7:0
0000_0000
Two’s complement format.
LSB is 0.25mV.
Range is +/-32mV
(Read-Only Register)
Register 54h DC Servo Readback 4
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R90 (5Ah)
Analogue HP
0
Removes HPL short
7
HPL_RMV_SHORT
0
0 = HPL short enabled
1 = HPL short removed
For normal operation, this bit should be set as the
final step of the HPL Enable sequence.
Enables HPL output stage
0 = Disabled
6
HPL_ENA_OUTP
0
1 = Enabled
For normal operation, this bit should be set to 1
after the DC offset cancellation has been
scheduled.
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Enables HPL intermediate stage
0 = Disabled
5
HPL_ENA_DLY
0
1 = Enabled
For normal operation, this bit should be set to 1
after the output signal path has been configured,
and before DC offset cancellation is scheduled.
This bit should be set with at least 20us delay after
HPL_ENA.
Enables HPL input stage
0 = Disabled
4
3
2
HPL_ENA
0
0
0
1 = Enabled
For normal operation, this bit should be set as the
first step of the HPL Enable sequence.
Removes HPR short
0 = HPR short enabled
1 = HPR short removed
HPR_RMV_SHORT
HPR_ENA_OUTP
For normal operation, this bit should be set as the
final step of the HPR Enable sequence.
Enables HPR output stage
0 = Disabled
1 = Enabled
For normal operation, this bit should be set to 1
after the DC offset cancellation has been
scheduled.
Enables HPR intermediate stage
0 = Disabled
1
HPR_ENA_DLY
0
1 = Enabled
For normal operation, this bit should be set to 1
after the output signal path has been configured,
and before DC offset cancellation is scheduled.
This bit should be set with at least 20us delay after
HPR_ENA.
Enables HPR input stage
0 = Disabled
0
HPR_ENA
0
1 = Enabled
For normal operation, this bit should be set as the
first step of the HPR Enable sequence.
Register 5Ah Analogue HP 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Removes LINEOUTL short
R94 (5Eh)
Analogue
Lineout 0
7
LINEOUTL_RMV_SHORT
LINEOUTL_ENA_OUTP
0
0 = LINEOUTL short enabled
1 = LINEOUTL short removed
For normal operation, this bit should be set as
the final step of the LINEOUTL Enable
sequence.
Enables LINEOUTL output stage
0 = Disabled
6
0
1 = Enabled
For normal operation, this bit should be set to
1 after the DC offset cancellation has been
scheduled.
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Enables LINEOUTL intermediate stage
0 = Disabled
5
LINEOUTL_ENA_DLY
0
1 = Enabled
For normal operation, this bit should be set to
1 after the output signal path has been
configured, and before DC offset cancellation
is scheduled. This bit should be set with at
least 20us delay after LINEOUTL_ENA.
Enables LINEOUTL input stage
0 = Disabled
4
3
2
1
LINEOUTL_ENA
0
0
0
0
1 = Enabled
For normal operation, this bit should be set as
the first step of the LINEOUTL Enable
sequence.
Removes LINEOUTR short
0 = LINEOUTR short enabled
1 = LINEOUTR short removed
LINEOUTR_RMV_SHORT
LINEOUTR_ENA_OUTP
LINEOUTR_ENA_DLY
For normal operation, this bit should be set as
the final step of the LINEOUTR Enable
sequence.
Enables LINEOUTR output stage
0 = Disabled
1 = Enabled
For normal operation, this bit should be set to
1 after the DC offset cancellation has been
scheduled.
Enables LINEOUTR intermediate stage
0 = Disabled
1 = Enabled
For normal operation, this bit should be set to
1 after the output signal path has been
configured, and before DC offset cancellation
is scheduled. This bit should be set with at
least 20us delay after LINEOUTR_ENA.
Enables LINEOUTR input stage
0 = Disabled
0
LINEOUTR_ENA
0
1 = Enabled
For normal operation, this bit should be set as
the first step of the LINEOUTR Enable
sequence.
Register 5Eh Analogue Lineout 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R98 (62h)
Charge
Pump 0
Enable charge-pump digits
0
CP_ENA
0
0 = disable
1 = enable
Register 62h Charge Pump 0
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R104 (68h)
Class W 0
Enable dynamic charge pump power control
0
CP_DYN_PWR
0
0 = charge pump controlled by volume register
settings
1 = charge pump controlled by real-time audio level
Register 68h Class W 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R108 (6Ch)
Write
Sequencer 0
Write Sequencer / Mic Detect Clock Enable.
8
WSMD_CLK_ENA
0
0 = Disabled
1 = Enabled
Sequence Write Index. This is the memory
location to which any updates to R109 and
R110 will be copied.
4:0
WSEQ_WRITE_INDEX
[4:0]
0_0000
0 to 31 = RAM addresses
Register 6Ch Write Sequencer 0
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R109 (6Dh)
Write
Width of the data block written in this
sequence step.
14:12
WSEQ_DATA_WIDTH
[2:0]
000
Sequencer 1
000 = 1 bit
001 = 2 bits
010 = 3 bits
011 = 4 bits
100 = 5 bits
101 = 6 bits
110 = 7 bits
111 = 8 bits
Bit position of the LSB of the data block
written in this sequence step.
11:8
7:0
WSEQ_DATA_START
[3:0]
0000
0000 = Bit 0
…
1111 = Bit 15
Control Register Address to be written to in
this sequence step.
WSEQ_ADDR [7:0]
0000_0000
Register 6Dh Write Sequencer 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R110 (6Eh)
Write
Sequencer 2
End of Sequence flag. This bit indicates whether
the Control Write Sequencer should stop after
executing this step.
14
WSEQ_EOS
0
0 = Not end of sequence
1 = End of sequence (Stop the sequencer after this
step).
Time delay after executing this step.
Total delay time per step (including execution)=
62.5µs × (2^WSEQ_DELAY + 8)
11:8
WSEQ_DELAY
[3:0]
0000
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Data to be written in this sequence step. When the
data width is less than 8 bits, then one or more of
the MSBs of WSEQ_DATA are ignored. It is
recommended that unused bits be set to 0.
7:0
WSEQ_DATA [7:0] 0000_0000
Register 6Eh Write Sequencer 2
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R111 (6Fh)
Write
Sequencer 3
Writing a 1 to this bit aborts the current
sequence and returns control of the device
back to the serial control interface.
9
WSEQ_ABORT
0
(Write-Only Register)
Writing a 1 to this bit starts the write
8
WSEQ_START
0
sequencer at the memory location indicated
by the WSEQ_START_INDEX field. The
sequence continues until it reaches an “End of
sequence” flag. At the end of the sequence,
this bit will be reset by the Write Sequencer.
(Write-Only Register)
Sequence Start Index. This is the memory
location of the first command in the selected
sequence.
5:0
WSEQ_START_INDEX
[5:0]
00_0000
0 to 31 = RAM addresses
32 to 48 = ROM addresses
49 to 63 = Reserved
Register 6Fh Write Sequencer 3
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R112 (70h)
Write
Sequencer 4
Sequence Current Index. This is the
location of the most recently accessed
command in the write sequencer memory.
9:4
WSEQ_CURRENT_INDEX
[5:0]
00_0000
(Read-Only Register)
Sequencer Busy flag
0 = Sequencer idle
1 = Sequencer busy
0
WSEQ_BUSY
0
Note: it is not possible to write to control
registers via the control interface while the
Sequencer is Busy.
(Read-Only Register)
Register 70h Write Sequencer 4
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
GPIO 1 Pin Function select
R116 (74h)
GPIO Control
1
13:8
GP1_FN [5:0]
00_0000
00h = GPIO output
01h = Reserved
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = DMIC_LR Clock output
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GPIO Pin Direction
7
6
5
4
GP1_DIR
GP1_OP_CFG
GP1_IP_CFG
GP1_LVL
1
0
1
0
0 = Output
1 = Input
Output pin configuration
0 = CMOS
1 = Open-drain
Input pin configuration
0 = Active low
1 = Active high
GPIO Output Level
(when GP1_FN = 00000)
0 = Logic 0
1 = Logic 1
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
0 = Level triggered
1 = Edge triggered
GPIO de-bounce
3
2
1
0
GP1_PD
GP1_PU
1
0
0
0
GP1_INTMODE
GP1_DB
0 = GPIO is not debounced
1 = GPIO is debounced
Register 74h GPIO Control 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R117 (75h)
GPIO Control
2
GPIO 2 Pin Function select
00h = GPIO output
13:8
GP2_FN [5:0]
00_0000
01h = Reserved
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = DMIC_DAT Data input
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
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REGISTER
ADDRESS
BIT
7
LABEL
GP2_DIR
DEFAULT
DESCRIPTION
0Ah to 3Fh = Reserved
GPIO Pin Direction
0 = Output
1
0
1
0
1 = Input
Output pin configuration
0 = CMOS
6
GP2_OP_CFG
GP2_IP_CFG
GP2_LVL
1 = Open-drain
Input pin configuration
0 = Active low
5
1 = Active high
GPIO Output Level
(when GP2_FN = 00000)
0 = Logic 0
4
1 = Logic 1
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
0 = Level triggered
1 = Edge triggered
GPIO de-bounce
3
2
1
0
GP2_PD
GP2_PU
1
0
0
0
GP2_INTMODE
GP2_DB
0 = GPIO is not debounced
1 = GPIO is debounced
Register 75h GPIO Control 2
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R118 (76h)
GPIO Control
3
GPIO 3 Pin Function select
00h = GPIO output
13:8
GP3_FN [5:0]
00_0000
01h = Reserved
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = Reserved
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GPIO Pin Direction
0 = Output
7
6
5
GP3_DIR
1
0
1
1 = Input
Output pin configuration
0 = CMOS
GP3_OP_CFG
GP3_IP_CFG
1 = Open-drain
Input pin configuration
0 = Active low
1 = Active high
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
GPIO Output Level
4
GP3_LVL
0
(when GP3_FN = 00000)
0 = Logic 0
1 = Logic 1
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
3
2
1
0
GP3_PD
GP3_PU
1
0
0
0
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
0 = Level triggered
GP3_INTMODE
GP3_DB
1 = Edge triggered
GPIO de-bounce
0 = GPIO is not debounced
1 = GPIO is debounced
Register 76h GPIO Control 3
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R119 (77h)
GPIO Control
4
GPIO 4 Pin Function select
00h = GPIO output
13:8
GP4_FN [5:0]
00_0010
01h = Reserved
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = Reserved
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GPIO Pin Direction
0 = Output
7
6
5
4
GP4_DIR
GP4_OP_CFG
GP4_IP_CFG
GP4_LVL
0
0
1
0
1 = Input
Output pin configuration
0 = CMOS
1 = Open-drain
Input pin configuration
0 = Active low
1 = Active high
GPIO Output Level
(when GP4_FN = 00000)
0 = Logic 0
1 = Logic 1
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
1 = Pull-up enabled (Approx 100kΩ)
3
2
GP4_PD
GP4_PU
0
0
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
GPIO Interrupt Mode
1
GP4_INTMODE
0
0 = Level triggered
1 = Edge triggered
GPIO de-bounce
0
GP4_DB
0
0 = GPIO is not debounced
1 = GPIO is debounced
Register 77h GPIO Control 4
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R120 (78h)
GPIO Control
5
GPIO 5 Pin Function select
00h = GPIO output
13:8
GP5_FN [5:0]
00_0001
01h = BCLK
02h = IRQ output
03h = GPIO input
04h = MICBIAS Current detect
05h = MICBIAS Short Circuit detect
06h = Reserved
07h = Reserved
08h = FLL Lock output
09h = FLL Clock output
0Ah to 3Fh = Reserved
GPIO Pin Direction
0 = Output
7
6
5
4
GP5_DIR
GP5_OP_CFG
GP5_IP_CFG
GP5_LVL
1
0
1
0
1 = Input
Output pin configuration
0 = CMOS
1 = Open-drain
Input pin configuration
0 = Active low
1 = Active high
GPIO Output Level
(when GP5_FN = 00000)
0 = Logic 0
1 = Logic 1
GPIO Pull-Down Enable
0 = Pull-down disabled
1 = Pull-down enabled (Approx 100kΩ)
GPIO Pull-Up Enable
0 = Pull-up disabled
1 = Pull-up enabled (Approx 100kΩ)
GPIO Interrupt Mode
0 = Level triggered
1 = Edge triggered
GPIO de-bounce
3
2
1
0
GP5_PD
GP5_PU
0
0
0
0
GP5_INTMODE
GP5_DB
0 = GPIO is not debounced
1 = GPIO is debounced
Register 78h GPIO Control 5
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R121 (79h)
Interrupt
Status 1
MICBIAS Short Circuit detect IRQ status
0 = Short Circuit current IRQ not set
1 = Short Circuit current IRQ set
(Read-Only Register)
15
MICSHRT_EINT
0
MICBIAS Current detect IRQ status
0 = Current detect IRQ not set
1 = Current detect IRQ set
(Read-Only Register)
14
13
MICDET_EINT
0
0
Write Sequencer Busy IRQ status
0 = WSEQ IRQ not set
WSEQ_BUSY_EINT
1 = WSEQ IRQ set
The Write Sequencer asserts this flag when it has
completed a programmed sequence - ie it
indicates that the Write Sequencer is NOT Busy.
(Read-Only Register)
FLL_LOCK_EINT
GP5_EINT
FLL Lock IRQ status
0 = FLL Lock IRQ not set
1 = FLL Lock IRQ set
(Read-Only Register)
GPIO5 IRQ status
5
4
0
0
0 = GPIO5 IRQ not set
1 = GPIO5 IRQ set
(Read-Only Register)
GPIO4 IRQ status
3
2
1
0
GP4_EINT
GP3_EINT
GP2_EINT
GP1_EINT
0
0
0
0
0 = GPIO4 IRQ not set
1 = GPIO4 IRQ set
(Read-Only Register)
GPIO3/ADDR IRQ status
0 = GPIO3 IRQ not set
1 = GPIO3 IRQ set
(Read-Only Register)
GPIO2/DMIC_DAT IRQ status
0 = GPIO2 IRQ not set
1 = GPIO2 IRQ set
(Read-Only Register)
GPIO1/DMIC_LR IRQ status
0 = GPIO1 IRQ not set
1 = GPIO1 IRQ set
(Read-Only Register)
Register 79h Interrupt Status 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R122 (7Ah)
Interrupt
Status 1
Mask
Interrupt mask for MIC Short Circuit Detect
0 = Not masked
15
IM_MICSHRT_EINT
1
1
1 = Masked
Interrupt mask for MIC Current Detect
0 = Not masked
14
IM_MICDET_EINT
1 = Masked
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Interrupt mask for WSEQ Busy indication
0 = Not masked
13
IM_WSEQ_BUSY_EINT
1
1 = Masked
IM_FLL_LOCK_EINT
IM_GP5_EINT
Interrupt mask for FLL Lock
0 = Not masked
5
4
1
1
1 = Masked
Interrupt mask for GPIO5
0 = Not masked
1 = Masked
Interrupt mask for GPIO4
0 = Not masked
3
2
1
0
IM_GP4_EINT
IM_GP3_EINT
IM_GP2_EINT
IM_GP1_EINT
1
1
1
1
1 = Masked
Interrupt mask for GPIO3/ADDR
0 = Not masked
1 = Masked
Interrupt mask for GPIO2/DMIC_DAT
0 = Not masked
1 = Masked
Interrupt mask for GPIO1/DMIC_LR
0 = Not masked
1 = Masked
Register 7Ah Interrupt Status 1 Mask
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R123 (7Bh)
Interrupt
Polarity 1
MICBIAS Short Circuit detect polarity
15
MICSHRT_INV
0
0 = Detect current increase above threshold
1 = Detect current decrease below threshold
MICBIAS Current Detect polarity
14
5
MICDET_INV
0
0
0 = Detect current increase above threshold
1 = Detect current decrease below threshold
FLL_LOCK_INV
FLL Lock polarity
0 = Non-inverted
1 = Inverted
Register 7Bh Interrupt Polarity 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R126 (7Eh)
Interrupt
Control
Interrupt Output polarity
0 = Active high
0
IRQ_POL
0
1 = Active low
Register 7Eh Interrupt Control
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WM8903
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Gain applied to error
R128 (80h)
FLL Control
1
FLL_GAIN [3:0]
7:4
0000
0000 = x 1 (Recommended value)
0001 = x 2
0010 = x 4
0011 = x 8
0100 = x 16
0101 = x 32
0110 = x 64
0111 = x 128
1000 = x 256
Recommended that this register is not changed from
default.
FLL_HOLD
FLL_FRAC
FLL Hold Select
0 = Disabled
1 = Enabled
3
2
0
0
This feature enables free-running mode in FLL when
reference clock is removed
Fractional enable
0 = Integer Mode
1 = Fractional Mode
Fractional Mode is recommended in all cases
FLL_ENA
FLL Enable
0 = Disabled
1 = Enabled
0
0
Register 80h FLL Control 1
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R129 (81h)
FLL Control
2
FLL_CLK_SRC
[1:0]
FLL Clock source
00 = MCLK
12:11
00
01 = BCLK
10 = LRC
11 = Reserved
FLL Clock Reference Divider
00 = MCLK / 1
01 = MCLK / 2
10 = MCLK / 4
11 = MCLK / 8
FLL_CLK_REF
_DIV [1:0]
10:9
00
MCLK (or other input reference) must be divided down
to <=13.5MHz.
For lower power operation, the reference clock can be
divided down further if desired.
FLL_CTRL_RA
TE [2:0]
Frequency of the FLL control block
000 = FVCO / 1 (Recommended value)
001 = FVCO / 2
8:6
000
010 = FVCO / 3
011 = FVCO / 4
100 = FVCO / 5
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REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
101 = FVCO / 6
110 = FVCO / 7
111 = FVCO / 8
Recommended that this register is not changed from
default.
FLL_OUTDIV
[2:0]
FOUT clock divider
000 = 2
5:3
000
001 = 4
010 = 8
011 = 16
100 = 32
101 = 64
110 = 128
111 = 256
(FOUT = FVCO / FLL_OUTDIV)
FLL_FRATIO
[2:0]
FVCO clock divider
2:0
000
000 = divide by 1
001 = divide by 2
010 = divide by 4
011 = divide by 8
1XX = divide by 16
000 recommended for FREF > 1MHz
100 recommended for FREF < 64kHz
Register 81h FLL Control 2
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R130 (82h)
FLL Control
3
FLL_K [15:0]
Fractional multiply for FREF
(MSB = 0.5)
15:0
0000_0000
_0000_000
0
Register 82h FLL Control 3
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R131 (83h)
FLL Control
4
FLL_N [9:0]
Integer multiply for FREF
(LSB = 1)
9:0
00_0000_0
000
Register 83h FLL Control 4
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R164 (A4h)
Clock Rate
Test 4
Enables Digital Microphone mode.
0 = Audio DSP input is from ADC
9
ADC_DIG_MIC
0
1 = Audio DSP input is from digital microphone
interface
Register A4h Clock Rate Test 4
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WM8903
REGISTER
ADDRESS
R172 (ACh)
BIT
LABEL
DEFAULT
DESCRIPTION
PGA_BIAS
[2:0]
Headphone and Lineout PGA bias control
000 = Normal bias
6:4
000
Analogue
Output Bias
0
001 = Normal bias x 1.5
010 = Normal bias x 0.75
011 = Normal bias x 0.5
100 = Normal bias x 0.33
101 = Normal bias
110 = Normal bias
111 = Normal bias x 2
Register ACh Analogue Output Bias 0
REGISTER
ADDRESS
R187 (BBh)
BIT
LABEL
DEFAULT
DESCRIPTION
OUTPUTS_BIAS
[2:0]
Headphone and Lineout Output Drivers bias control
000 = Normal bias
2:0
000
Analogue
Output Bias
2
001 = Normal bias x 1.5
010 = Normal bias x 0.75
011 = Normal bias x 0.5
100 = Normal bias x 0.33
101 = Normal bias
110 = Normal bias
111 = Normal bias x 2
Register BBh Analogue Output Bias 2
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APPLICATIONS INFORMATION
RECOMMENDED EXTERNAL COMPONENTS
Figure 67 Recommended External Components
Notes:
1. Decoupling Capacitors
X5R ceramic capacitor is recommended for capacitors C1, C2, C3, C4, C6, C7, C12 and C13.
All decoupling capacitors should be positioned as close to the WM8903 as possible.
The positioning of C12 and C13 is particularly important - these should be as close to the WM8903 as possible.
2. Charge Pump Capacitors
Specific recommendations for C5, C6 and C7 are provided in Table 85. Note that two different recommendations are provided
for these components; either of these components is suitable, depending upon size requirements and availability.
The positioning of C5 is very important - this should be as close to the WM8903 as possible.
It is important to select a suitable capacitor type for the Charge Pump. Note that the capacitance may vary with DC voltage;
care is required to ensure that required capacitance is achieved at the applicable operating voltage, as specified in Table 85.
The capacitor datasheet should be consulted for this information.
COMPONENT
REQUIRED
VALUE
PART NUMBER
VOLTAGE
TYPE
SIZE
CAPACITANCE
2.2F
2.2F
2.2F
4.7F
Kemet C0402C225M9PAC
MuRata GRM155R60J225ME15_EIA
MuRata GRM188R61A225KE34D
MuRata GRM155R60J475M_EIA
6.3v
6.3v
10v
X5R
X5R
X5R
X5R
0402
0402
0603
0402
C5 (CFB1-CFB2)
1F at 2VDC
2F at 2VDC
C6 (VNEG)
C7 (VPOS)
6.3v
Table 85 Charge Pump Capacitors
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3. Zobel Networks
The Zobel network shown in Figure 67 is required on HPOUTL, HPOUTR, LINEOUTL and LINEOUTR whenever that output is
enabled. Stability of these ground-referenced outputs across all process corners cannot be guaranteed without the Zobel
network components. (Note that, if any ground-referenced output pin is not required, the zobel network components can be
omitted from the output pin, and the pin can be left floating.) The Zobel network requirement is detailed further in the
applications note WAN_0212 “Class W Headphone Impedance Compensation”.
Zobel networks (CC16, C17, C18, C19, R9, R10, R11, R12) should be positioned reasonably close to the WM8903.
4. Microphone Grounding
R3 and R4 can be populated with other values to remove common mode noise on the microphone if required.
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MIC DETECTION SEQUENCE USING MICBIAS CURRENT
This section details an example sequence which summarises how the host processor can configure
and detect the events supported by the MICBIAS current detect function (see “Electret Condenser
Microphone Interface”):
Mic insertion/removal
Hook switch press/release
Figure 68 shows an example of how the MICBIAS current flow varies versus time, during mic
insertion and hook switch events. The Y axis is annotated with the Mic detection thresholds, and the
X axis is annotated with the stages of an example sequence as detailed in Table 86, to illustrate how
the host processor can implement mic insertion and hook switch detection.
The sequence assumes that the microphone insertion and hook switch detection functions are
monitored by polling the interrupt flags using the control interface. Note that the maximum mechanical
bounce times for mic insertion and removal must be fully understood by the software programmer.
A GPIO pin could be used as an alternative mechanism to monitor the MICBIAS detection functions.
This enables the host processor to detect mechanical bounce at any time.
Figure 68 Mic Insert and Hook Switch Detect: Example MICBIAS Current Plot
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STEP
DETAILS
Mic not inserted. To detect mic insertion, Host processor must initialise interrupts and clear MICDET_INV = 0. At every
step, the host processor should poll the interrupt status register.
1
Mechanical bounce of jack socket during Mic insertion. Host processor may already detect a mic insertion interrupt
(MICDET_EINT) during this step. Once detected, the host processor can set MICDET_INV = 1, unless mechanical
bounce can last longer than the shortest possible TDET, in which case the host processor should not set MICDET_INV = 1
until step 3.
2
Mic fully inserted. If not already set, the host processor must now set MICDET_INV = 1. To detect Hook switch press, the
host processor must clear MICSHRT_INV = 0. At this step, the diagram shows no AC current swing, due to a very low
ambient noise level.
3
Mic fully inserted. Diagram shows AC current swing due to high levels of background noise (such as wind).
4
5
Mechanical bounce during hook switch press. The hook switch interrupt is unlikely to be set during this step, because 10
successive samples of the MICBIAS current exceeding the hook switch threshold have not yet been sampled.
Hook switch is fully pressed down. After TSHORT, 10 successive samples of the MICBIAS current exceeding the hook
switch threshold have been detected, hence a hook switch interrupt (MICSHRT_EINT) will be generated, and the host
processor can immediately set MICSHRT_INV = 1.
6
Mechanical bounce during hook switch release. The hook switch interrupt is unlikely to be set during this step, because
10 successive samples of the MICBIAS current lower than the hook switch threshold have not yet been sampled.
7
8
Hook switch fully released. After TSHORT, 10 successive samples of the MICBIAS current lower than the hook switch
threshold have been detected, hence a hook switch interrupt (MICSHRT_EINT) will be generated, and the host processor
can immediately clear MICSHRT_INV = 0.
Mechanical bounce of jack socket during Mic removal. Host processor may already detect a mic removal interrupt
(MICDET_EINT) during this step. Once detected, the host processor can clear MICDET_INV = 0, unless mechanical
bounce can last longer than the shortest possible TDET, in which case the host processor should not clear MICDET_INV =
0 until step 10.
9
Mic fully removed. If not already cleared, the host processor must now clear MICDET_INV = 0.
10
Table 86 Mic Insert and Hook Switch Detect: Example Sequence
Alternatively, utilising a GPIO pin to monitor the MICBIAS current detect functionality permits the host
processor to monitor the steady state of microphone detection or hook switch press functions.
Because the GPIO shows the steady state condition, software de-bounce may be easier to implement
in the host processor, dependant on the processor performance characteristics, hence use of the
GPIO is likely to simplify the rejection of mechanical bounce. Changes of state in the GPIO pin are
also subject to the time delays tDET and tSHORT
.
Further details can be found in the applications note WAN_0213 “WM8903 ECM mic detection using
MICBIAS current”.
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PACKAGE DIMENSIONS
FL: 40 PIN QFN PLASTIC PACKAGE 5 X 5 X 0.55 mm BODY, 0.40 mm LEAD PITCH
DM110.A
D2
TOP VIEW
ddd
C
A
B
B
D
31
39 40
INDEX AREA
(D/2 X E/2)
40 x L
1
2
30
R0.2
(PIN #1 ID)
S
A
E2
ddd
EXPOSED
A
A
B
C
6
GND
E
PADDLE
21
10
SEE DETAIL A
aaa
C
2 X
2 X
11
40 x b
18 17
B
e
aaa
C
M
C
A
B
bbb
ccc
C
(A3)
1
A
0.08
C
DETAIL A
A1
SEATING PLANE
C
TERMINAL TIP
1
Dimensions (mm)
Symbols
MIN
0.50
0
NOM
0.55
MAX
0.60
0.05
NOTE
A
A1
A3
b
0.035
0.152 REF
0.20
0.15
3.30
3.30
0.25
3.50
3.50
1
2
2
D
5.00 BSC
3.40
D2
E
5.00 BSC
3.40
E2
e
0.4 BSC
0.4
L
0.35
1.15
0.45
1.35
S
1.25
Tolerances of Form and Position
aaa
bbb
ccc
0.10
0.10
0.10
0.10
ddd
REF:
JEDEC, MO-220 – WHHE-1
NOTES:
1. DIMENSION b APPLIED TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP.
2. FALLS WITHIN JEDEC, MO-220.
3. ALL DIMENSIONS ARE IN MILLIMETRES
4. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE.
5. REFER TO APPLICATIONS NOTE WAN_0118 FOR FURTHER INFORMATION.
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IMPORTANT NOTICE
Wolfson Microelectronics plc (“Wolfson”) products and services are sold subject to Wolfson’s terms and conditions of sale,
delivery and payment supplied at the time of order acknowledgement.
Wolfson warrants performance of its products to the specifications in effect at the date of shipment. Wolfson reserves the
right to make changes to its products and specifications or to discontinue any product or service without notice. Customers
should therefore obtain the latest version of relevant information from Wolfson to verify that the information is current.
Testing and other quality control techniques are utilised to the extent Wolfson deems necessary to support its warranty.
Specific testing of all parameters of each device is not necessarily performed unless required by law or regulation.
In order to minimise risks associated with customer applications, the customer must use adequate design and operating
safeguards to minimise inherent or procedural hazards. Wolfson is not liable for applications assistance or customer
product design. The customer is solely responsible for its selection and use of Wolfson products. Wolfson is not liable for
such selection or use nor for use of any circuitry other than circuitry entirely embodied in a Wolfson product.
Wolfson’s products are not intended for use in life support systems, appliances, nuclear systems or systems where
malfunction can reasonably be expected to result in personal injury, death or severe property or environmental damage.
Any use of products by the customer for such purposes is at the customer’s own risk.
Wolfson does not grant any licence (express or implied) under any patent right, copyright, mask work right or other
intellectual property right of Wolfson covering or relating to any combination, machine, or process in which its products or
services might be or are used. Any provision or publication of any third party’s products or services does not constitute
Wolfson’s approval, licence, warranty or endorsement thereof. Any third party trade marks contained in this document
belong to the respective third party owner.
Reproduction of information from Wolfson datasheets is permissible only if reproduction is without alteration and is
accompanied by all associated copyright, proprietary and other notices (including this notice) and conditions. Wolfson is
not liable for any unauthorised alteration of such information or for any reliance placed thereon.
Any representations made, warranties given, and/or liabilities accepted by any person which differ from those contained in
this datasheet or in Wolfson’s standard terms and conditions of sale, delivery and payment are made, given and/or
accepted at that person’s own risk. Wolfson is not liable for any such representations, warranties or liabilities or for any
reliance placed thereon by any person.
ADDRESS
Wolfson Microelectronics plc
Westfield House
26 Westfield Road
Edinburgh
EH11 2QB
Tel :: +44 (0)131 272 7000
Fax :: +44 (0)131 272 7001
Email :: sales@wolfsonmicro.com
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Production Data
REVISION HISTORY
DATE
REV
ORIGINATOR
CHANGES
Correction to Audio Interface, Slave Mode specifications. “DACDAT set-up
time to BCLK rising edge” specification changed to 20ns minimum.
21/07/11
4.1
SS
All Read-Only and Write-Only registers are specifically identified as Read-
Only or Write-Only respectively.
08/08/11
4.2
PH
LIN_VOL and RIN_VOL registers updated; 00000 = -1.55dB
28/09/11
01/03/12
4.3
4.4
PH
Order codes updated from WM8903LGEFK/V and WM8903LGEFK/RV to
WM8903CLGEFK and WM8903CLGEFK/R to reflect change to copper wire
bonding
JMacD
MSL level changed from MSL3 to MSL1
01/03/12
01/03/12
14/06/12
4.4
4.4
4.5
JMacD
JMacD
SS
Package Diagram changed to DM110.A
Correction to Audio Interface, Slave Mode specifications. “ADCDAT
propagation delay from BCLK falling edge” specification changed to 30ns
maximum.
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