MAX9791_V01 [MAXIM]
Windows Vista-Compliant Class D Speaker Amplifiers with DirectDrive Headphone Amplifiers;
| 型号： | MAX9791_V01 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Windows Vista-Compliant Class D Speaker Amplifiers with DirectDrive Headphone Amplifiers |
| 文件： | 总34页 (文件大小：826K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4217; Rev 1; 6/10
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
General Description
Features
The MAX9791 combines a stereo 2W Class D power
amplifier, a stereo 180mW DirectDrive® headphone
amplifier, and a 120mA low-dropout (LDO) linear regu-
lator in a single device. The MAX9792 combines a
mono 3W Class D power amplifier, a stereo 180mW
DirectDrive headphone amplifier, and a 120mA LDO
linear regulator in a single device.
o Windows Vista® Premium Compliant
o Low EMI Filterless Class D Speaker Amplifiers
Pass EN55022B Emissions Limit with 30cm of
Speaker Cable
o 180mW DirectDrive Headphone Amplifier
o Excellent RF Immunity
o Integrated 120mA LDO
o Eliminates Headphone Ground Loop Noise
o Wake-on-Beep Function
o Click-and-Pop Suppression
o Short-Circuit and Thermal-Overload Protection
The MAX9791/MAX9792 feature Maxim’s DirectDrive
headphone amplifier architecture that produces a
ground-referenced output from a single supply, eliminat-
ing the need for large DC-blocking capacitors, saving
cost, board space, and component height. High 107dB
DC PSRR and low 0.006% THD+N ensure clean, low-
distortion amplification of the audio signal.
The ground sense feature senses and corrects for the
voltage difference between the output jack ground and
device signal ground. This feature minimizes head-
phone amplifier crosstalk by sensing the impedance in
the ground return trace and correcting for it at the out-
put jack. This feature also minimizes ground-loop noise
when the output socket is used as a line out connection
to other grounded equipment (for example, a PC con-
nected to a home hi-fi system).
The MAX9791/MAX9792 feature low RF susceptibility,
allowing the amplifiers to successfully operate in close
proximity to wireless applications. The MAX9791/
MAX9792 Class D amplifiers feature Maxim’s spread-
spectrum modulation and active emissions limiting cir-
cuitry. Industry-leading click-and-pop suppression
eliminates audible transients during power-up and shut-
down cycles.
o Thermally Efficient, Space-Saving Package
28-Pin TQFN-EP (4mm x 4mm x 0.75mm)
Ordering Information
STEREO/
MONO
LDO
OUTPUT
PART
PIN-PACKAGE
MAX9791AETI+
MAX9791BETI+
MAX9791CETI+
MAX9792AETI+
MAX9792CETI+
Stereo
Stereo
Stereo
Mono
Mono
4.75V
3.3V
28 TQFN-EP*
28 TQFN-EP*
28 TQFN-EP*
28 TQFN-EP*
28 TQFN-EP*
1.8V
4.75V
1.8V
Note: All devices are specified over the -40°C to +85°C
extended temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
The MAX9791/MAX9792 wake-on-beep feature wakes
up the speaker and headphone amplifiers when a qual-
ified beep signal is detected at the BEEP input.
For maximum flexibility, separate speaker and head-
phone amplifier control inputs provide independent
shutdown of the speaker and headphone amplifiers.
Additionally the LDO can be enabled independently of
the audio amplifiers.
Simplified Block Diagrams
SPEAKER AND LDO
SUPPLY
2.7V TO 5.5V
HEADPHONE SUPPLY
2.7V TO 5.5V
CLASS D
AMP
MAX9791
The MAX9791/MAX9792 feature thermal-overload and
output short-circuit protection. The devices are avail-
able in 28-pin TQFN packages and are specified over
the -40°C to +85°C extended temperature range.
CLASS D
AMP
Applications
Notebook Computers
Tablet PCs
SPKR_EN
HP_EN
LDO_EN
BEEP
AVDD
LDO
Portable Multimedia Players
1.8V, 3.3V, OR 4.75V
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
Simplified Block Diagrams continued at end of data sheet.
Windows Vista is a registered trademark of Microsoft Corp.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
Continuous Input Current (All Other Pins) ........................ 20mA
(AVDD, PVDD, HPVDD to GND)........................-0.3V to +6.0V
(AVDD to PVDD) ............................................................. 0.3V
GND to PGND, CPGND...................................................... 0.3V
CPVSS, C1N to GND............................................-6.0V to + 0.3V
HPL, HPR to CPVSS ...........................................-0.3V to lower of
(HPVDD - CPVSS + 0.3V) and +9V
Continuous Power Dissipation (T = +70°C)
28-Pin Thin QFN Single-Layer Board (derate 20.8mW/°C
above +70°C)..........................................................1667mW
Junction-to-Ambient Thermal Resistance (θ
(Note 2) .....................................................................40°C/W
A
)
JA
Junction-to-Case Thermal Resistance (θ
)
JC
HPL, HPR to HPVDD..................................+0.3V to the higher of
(CPVSS - HPVDD - 0.3V) and -9V
(Note 2) ....................................................................2.7°C/W
28-Pin Thin QFN Multilayer Board (derate 28.6mW/°C
above +70°C)..........................................................2286mW
COM, SENSE........................................................-0.3V to + 0.3V
Any Other Pin ..........................................-0.3V to (AVDD + 0.3V)
Duration of Short Circuit between OUT_+, OUT_- and GND,
PGND, AVDD, or PVDD..........................................Continuous
Duration of Short Circuit between LDO_OUT and AVDD,
GND (Note 1) .........................................................Continuous
Duration of Short Circuit between HPR, HPL and
GND .......................................................................Continuous
Continuous Current (PVDD, OUT_+, OUT_-, PGND)............1.7A
Continuous Current (C1N, C1P, CPVSS, AVDD, HPVDD,
LDO_OUT, HPR, HPL) ..................................................850mA
Junction-to-Ambient Thermal Resistance (θ
(Note 2) .....................................................................35°C/W
)
JA
Junction-to-Case Thermal Resistance (θ
)
JC
(Note 2) ....................................................................2.7°C/W
ESD Protection, Human Body Model................................... 2kV
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
1/MAX792
Note 1: If short is present at power-up.
Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
= V
= V
= 5V, V
= V
= V
= 0, I
= 0, C
= 2µF (C
= 4µF for 1.8V LDO option),
LDO
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
LDO
C1 = C2 = 1µF. R = ∞, unless otherwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C = 470nF,
L
IN1
VSPKR
IN2
VHP
IN1
C
= C
= 1µF, T = T
to T
, unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
IN2
COM
A
MIN
MAX A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
GENERAL
V
V
,
AVDD
Supply Voltage
Guaranteed by PSRR test (Note 4)
Guaranteed by PSRR test
2.7
2.7
5.5
V
PVDD
Headphone Supply Voltage
Undervoltage Lockout
V
5.5
V
V
HPVDD
UVLO
2.65
SPKR_EN HP_EN LDO_EN
1
1
0
0
1
1
0
0
0
1
0
1
0
1
0
1
1
0
0
0
1
0
0
0
250
4.4
400
6
µA
mA
µA
MAX9791
10.5
14.4
250
4.4
15
21
400
6
I
I
I
+
AVDD
Quiescent Current
+
PVD
HPVDD
MAX9792
mA
10.5
14.4
3.3
18
24
7..3
Shutdown Current
Bias Voltage
I
SPKR_EN = 1.8V
HP_INR, HP_INL, SPKR_INR, SPKR_INL
µA
V
SHDN
V
0
BIAS
2
_______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= V
= 5V, V
= V
= V
= 0, I
= 0, C
= 2µF (C
= 4µF for 1.8V LDO option),
LDO
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
LDO
C1 = C2 = 1µF. R = ∞, unless otherwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C = 470nF,
L
IN1
VSPKR
IN2
VHP
IN1
C
= C
= 1µF, T = T
to T
, unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
IN2
COM
A
MIN
MAX A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
0.4
MAX
UNITS
ms
Shutdown to Full Operation
Overtemperature Threshold
SPEAKER AMPLIFIER
t
ON
+150
°C
R = 4ꢀ
(MAX9791)
L
1.7
1.2
3
THD+N = 1%,
f = 1kHz,
R = 8ꢀ
L
T
A
= +25°C
(MAX9791)
(Note 5)
R = 3ꢀ
L
(MAX9792)
Output Power
P
W
OUT
R = 4ꢀ
(MAX9791)
L
2.2
1.5
3.7
THD+N = 10%,
f = 1kHz,
R = 8ꢀ
L
T
A
= +25°C
(MAX9791)
(Note 5)
R = 3ꢀ
L
(MAX9792)
R = 8ꢀ , P
= 500mW, f = 1kHz (Note 5)
= 500mW, f = 1kHz (Note 5)
0.04
0.03
80
Total Harmonic Distortion Plus
Noise
L
OUT
OUT
THD+N
PSRR
%
R = 4ꢀ , P
L
V
AVDD
= V
= 2.7V to 5.5V, T = +25°C
60
PVDD
A
f = 217Hz, 200mV
73
P-P
Power-Supply Rejection Ratio
dB
f = 1kHz, 200mV
75
P-P
f = 10kHz, 200mV
62
P-P
Feedback Impedance
Gain
R
Guaranteed by design
= 20kꢀ
20
kꢀ
FSKR
A
R
12
dB
V
IN1
Measured between OUT_+ and OUT_-,
= +25°C
Output Offset Voltage
V
3
10
mV
OS
T
A
R = 8ꢀ ,
peak voltage,
L
Into shutdown
-52.4
Click-and-Pop Level
K
CP
A-weighted,
dBV
Out of
shutdown
32 samples per second
(Notes 5, 6, and 7)
-54
98
R = 8ꢀ
L
A-weighted
P
= 1.2W f = 1kHz,
IN
Signal-to-Noise Ratio
Noise
SNR
dB
OUT
20Hz to 20kHz
94
38
(Note 5)
V
N
A-weighted
µV
RMS
L to R, R to L, R = 8ꢀ , V = -20dBFS =
L
IN
78
70
77
100mV
, f = 1kHz (Note 5)
RMS IN
L to R, R to L, R = 8ꢀ , V = -20dBFS =
L
IN
Crosstalk
dB
100mV
, f = 15kHz (Note 5)
RMS IN
HP to SPKR, R
= 8ꢀ , P = 20mW,
HP
LSPKR
R
LHP
= 32ꢀ , f = 1kHz (Note 5)
IN
_______________________________________________________________________________________
3
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= V
= 5V, V
= V
= V
= 0, I
= 0, C
= 2µF (C
= 4µF for 1.8V LDO option),
LDO
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
LDO
C1 = C2 = 1µF. R = ∞, unless otherwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C = 470nF,
L
IN1
VSPKR
IN2
VHP
IN1
C
= C
= 1µF, T = T
to T
, unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
IN2
COM
A
MIN
MAX A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
kHz
kHz
%
Class D Switching Frequency
Spread-Spectrum Bandwidth
Efficiency
f
948
1158
SPK
15
83
P
= 1.5W, f = 1kHz, R = 8ꢀ (Note 5)
IN L
OUT
HEADPHONE AMPLIFIER
THD+N = 1%,
f = 1kHz,
R = 16ꢀ
100
180
L
Output Power
P
mW
OUT
R = 32ꢀ
L
T
A
= +25°C
R = 32ꢀ , f = 6kHz, 20kHz AES17,
L
IN
-78
-87
V
= -3dBFS = 212mV
IN
RMS
dBFS
Total Harmonic Distortion Plus
Noise
R = 10kꢀ , f = 6kHz, 20kHz AES17,
L
IN
THD+N
PSRR
V
= -3dBFS = 500mV
IN
RMS
1/MAX792
R = 32ꢀ , P
= 100mW, f = 1kHz
= 75mW, f = 1kHz
0.006
0.014
107
91
L
OUT
OUT
%
R = 16ꢀ , P
L
V
= 2.7V to 5.5V, T = +25°C
70
HPVDD
A
Power-Supply Rejection Ratio
dB
f = 1kHz, V
= 200mV
P-P
RIPPLE
f = 10kHz, V
= 200mV
80
RIPPLE
P-P
Feedback Impedance
Gain
R
38.2
40.2
0
42.2
3
kꢀ
dB
mV
FHP
A
R
= 40.2kꢀ
IN2
V
Output Offset Voltage
V
T
A
= +25°C
0.3
OS
R = 32ꢀ ,
peak voltage,
A-weighted, 32 samples
per second (Notes 6, 7)
L
Into shutdown
-81
Click-and-Pop Level
Signal-to-Noise Ratio
K
dBV
dB
CP
Out of
shutdown
-72.5
A-weighted
= 40mW,
102
94
R = 32ꢀ , P
L
OUT
SNR
f
= 1kHz
IN
20Hz to 20kHz
Noise
V
A-weighted
No sustained oscillations
8
µV
RMS
N
Maximum Capacitive Load
C
100
pF
L
R = 32ꢀ , V
-20dBFS = 30mV
=
IN
L
L to R, R to L, f
= 1kHz, COM
and SENSE
IN
82
89
64
70
80
RMS
R = 10kꢀ , V
=
IN
L
connected
-20dBFS = 0.7mV
RMS
R = 32ꢀ , V
=
IN
L
L to R, R to L, f
= 15kHz, COM
and SENSE
IN
Crosstalk
dB
-20dBFS = 30mV
RMS
R = 10kꢀ , V
=
IN
L
connected
-20dBFS = 70.7mV
RMS
SPKR to HP, R
= 8ꢀ , P
= 1W,
SPKR
LSPKR
R
LHP
= 32ꢀ , f = 1Hz
IN
4
_______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= V
= 5V, V
= V
= V
= 0, I
= 0, C
= 2µF (C
= 4µF for 1.8V LDO option),
LDO
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
LDO
C1 = C2 = 1µF. R = ∞, unless otherwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C = 470nF,
L
IN1
VSPKR
IN2
VHP
IN1
C
= C
= 1µF, T = T
to T
, unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
IN2
COM
A
MIN
MAX A
PARAMETER
COM Input Range
SYMBOL
CONDITIONS
Inferred from CMRR test
-300mV < V < +300mV
MIN
TYP
MAX
UNITS
mV
V
COM
-300
+300
Common-Mode Rejection Ratio
Slew Rate
CMRR
SR
60
dB
COM
0.38
530
V/µs
kHz
Charge-Pump Frequency
BEEP INPUT (LDO_EN = 1)
Beep Signal Minimum
f
OSC
f
Four-cycle count
215
221
Hz
ms
ms
BEEP
Amplifier Turn-On Time
Amplifier Hold Time
t
0.4
ONBEEP
t
246
271
HOLDBEEP
LOW-DROPOUT LINEAR REGULATOR
LDO Ground Current
Output Current
Current Limit
I
0.25
0.4
mA
mA
mA
LDO
OUT
I
Inferred from load regulation
120
I
300
-80
LIM
Speaker to LDO, V
= 4.75V,
LDO_OUT
Crosstalk
f =1kHz, I
= 10mA, speaker P
dB
%
LDO_OUT
OUT
= 1.2W, R = 8ꢀ (Note 6)
L
V
V
V
= 4.75V
= 3.3V
1.5
1.5
LDO_OUT
LDO_OUT
LDO_OUT
Output-Voltage Accuracy
I
I
= 50mA
46
106
30
= 4.75V,
= +25°C (Note 8)
OUT
OUT
Dropout Voltage
Startup Time
V
mV
µs
DO
T
A
= 120mA
V
= 5V to 5.5V, V
LDO_OUT
= 4.75V,
AVDD
-4.8
-4
1.5
0.2
+4.8
+4
I
= 1mA, C
= 2µF
LDO
LDO_OUT
V
AVDD
= 4.5V to 5.5V, V
= 3.3V,
LDO_OUT
= 2µF
Line Regulation
mV/V
I
= 1mA, C
LDO
LDO_OUT
V
= 3V to 5.5V, V
= 1.8V,
AVDD
LDO_OUT
-6.4
2.5
+6.4
I
= 1mA, C
= 4µF
LDO
LDO_OUT
V
= 4.75V, 1mA < I
<
LDO_OUT
LDO_OUT
Load Regulation
0.22
mV/mA
dB
120mA
V
V
I
= 200mV
,
RIPPLE
P-P
f = 1kHz
f = 10kHz
56
40
Ripple Rejection
= 4.75V
= 10mA
LDO_OUT
LDO_OUT
20Hz to 20kHz, C
= 2 x 1µF,
LDO_OUT
Output-Voltage Noise
130
µV
RMS
I
= 120mA
LDO_OUT
DIGITAL INPUTS (SPKR_EN, HP_EN, LDO_EN, BEEP)
Input-Voltage High
Input-Voltage Low
Input Bias Current
V
1.4
-1
V
V
INH
V
0.4
+1
INL
µA
_______________________________________________________________________________________
5
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= V
= 5V, V
= V
= V
= 0, I
= 0, C
= 2µF (C
= 4µF for 1.8V LDO option),
LDO
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
LDO
C1 = C2 = 1µF. R = ∞, unless otherwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF,
L
IN1
VSPKR
IN2
VHP
IN1
C
= C
= 1µF, T = T
to T
, unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
IN2
COM
A
MIN
MAX A
Note 3: All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design.
Note 4: AVDD and PVDD must be tied together. If LDO is enabled, set AVDD and PVDD as specified in the Line Regulation row of
the Electrical Characteristics table.
Note 5: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For R = 3Ω, L = 22µH.
L
For R = 4Ω, L = 33µH. For R = 8Ω, L = 68µH.
L
L
Note 6: Specified at T = +25°C with an 8Ω + 68µH load connected across BTL output for speaker amplifier. Specified at T = +25°C
A
A
with a 32Ω resistive load connected between HPR, HPL and GND for headphone amplifier. Speaker and headphone mode
transitions are controlled by SPKR_EN and HP_EN inputs, respectively.
Note 7: Amplifier Inputs AC-coupled to GND.
Note 8: Guaranteed by ATE characterization; limits are not production tested.
Typical Operating Characteristics
(V
= V
= V
IN1
= 5V, V
= V
= 12dB), R
= V
IN2
= 0, I
= 40.2kΩ (A
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
VHP
erwise specified. R
= 20kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
1/MAX792
HP_EN = 1.)
SPEAKER
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (MAX9792 SPEAKER MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (MAX9791 SPEAKER MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (MAX9791 SPEAKER MODE)
0
0
0
R = 3Ω
IN
R = 4Ω
IN
R = 8Ω
L
L
L
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
V
= -3dBFS
V
= -3dBFS
V = -3dBFS
IN
FS = 707mV
FS = 707mV
RMS
RMS
FS = 1V
RMS
FS = 1V
RMS
FS = 1V
1
RMS
FS = 707mV
1
RMS
0.01
0.1
10
100
0.01
0.1
10
100
0.01
0.1
1
FREQUENCY (kHz)
10
100
FREQUENCY (kHz)
FREQUENCY (kHz)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (MAX9792 SPEAKER MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (MAX9791 SPEAKER MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (MAX9791 SPEAKER MODE)
100
100
100
R = 3Ω
L
R = 4Ω
L
R = 8Ω
L
10
10
10
f = 6kHz
f = 6kHz
f = 6kHz
f = 1kHz
1
1
0.1
1
f = 1kHz
f = 1kHz
0.1
0.1
0.01
0.01
0.001
0.01
f = 100Hz
f = 100Hz
f = 100Hz
0.001
0.001
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
OUTPUT POWER (W)
0
0.5
1.0
1.5
2.0
2.5
3.0
0
0.5
1.0
1.5
2.0
OUTPUT POWER (W)
OUTPUT POWER (W)
6
_______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
SPEAKER
OUTPUT POWER vs. LOAD RESISTANCE
(MAX9792 SPEAKER MODE)
OUTPUT POWER vs. LOAD RESISTANCE
(MAX9792 SPEAKER MODE)
5.0
4.5
2.5
2.0
1.5
1.0
0.5
0
f = 1kHz
V
PVDD
= V
= 3.7V
AVDD
4.0
3.5
THD+N = 10%
3.0
2.5
THD+N = 1%
THD+N = 10%
2.0
1.5
1.0
0.5
0
THD+N = 1%
1
10
100
1
10
100
LOAD RESISTANCE (Ω)
LOAD RESISTANCE (Ω)
OUTPUT POWER vs. LOAD RESISTANCE
(MAX9791 SPEAKER MODE)
OUTPUT POWER vs. LOAD RESISTANCE
(MAX9791 SPEAKER MODE)
EFFICIENCY vs. OUTPUT POWER
(MAX9792 SPEAKER MODE)
3.0
2.5
2.0
1.50
1.25
1.00
0.75
0.50
0.25
0
110
100
90
80
70
60
50
40
30
20
10
0
f = 1kHz
V
= V
AVDD
= 3.7V
PVDD
R = 8Ω
L
THD+N = 10%
R = 3Ω
L
THD+N = 1%
1.5
1.0
THD+N = 10%
THD+N = 1%
10
0.5
0
f
= 1kHz
IN
1
10
100
1
100
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
OUTPUT POWER (W)
LOAD RESISTANCE (Ω)
LOAD RESISTANCE (Ω)
EFFICIENCY vs. OUTPUT POWER
(MAX9792 SPEAKER MODE)
EFFICIENCY vs. OUTPUT POWER
(MAX9791 SPEAKER MODE)
EFFICIENCY vs. OUTPUT POWER
(MAX9791 SPEAKER MODE)
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
90
80
70
60
50
40
30
20
10
0
R = 8Ω
L
R = 8Ω
L
R = 8Ω
L
R = 3Ω
L
R = 4Ω
L
R = 4Ω
L
f
= 1kHz
1.5
V
= V
= 3.7V
V
PVDD
= V
AVDD
= 3.7V
IN
PVDD
AVDD
f
IN
= 1kHz
f = 1kHz
IN
0
0.3
0.6
0.9
1.2
1.5
0
0.3
0.6
0.9
1.2
1.8
0
0.2
0.4
0.6
0.8
1.0
OUTPUT POWER (W)
OUTPUT POWER (W)
OUTPUT POWER (W)
_______________________________________________________________________________________
7
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
SPEAKER
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX9791 SPEAKER MODE)
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX9791 SPEAKER MODE)
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX9792 SPEAKER MODE)
3.0
2.5
2.0
1.5
1.0
0.5
0
2.0
1.5
1.0
0.5
0
2.5
2.0
1.5
1.0
0.5
0
f = 1kHz
f = 1kHz
f = 1kHz
R
= 4Ω
R
= 8Ω
R
= 8Ω
LOAD
LOAD
LOAD
THD+N = 10%
THD+N = 10%
THD+N = 10%
THD+N = 1%
THD+N = 1%
THD+N = 1%
1/MAX792
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX9792 SPEAKER MODE)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY (SPEAKER MODE)
CROSSTALK vs. FREQUENCY
(SPEAKER MODE)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
0
f = 1kHz
V
= 200mV
FS = 1V
RMS
V = -20dBFS
R = 8Ω
RIPPLE
P-P
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
R
= 3Ω
LOAD
R = 8Ω
L
IN
L
THD+N = 10%
LEFT
RIGHT TO LEFT
THD+N = 1%
RIGHT
LEFT TO RIGHT
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0.01
0.1
1
10
100
0.01
0.1
1
10
100
SUPPLY VOLTAGE
FREQUENCY (kHz)
FREQUENCY (kHz)
8
_______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
SPEAKER
SPEAKER STARTUP WAVEFORM
SPEAKER SHUTDOWN WAVEFORM
MAX9791 toc14
MAX9791 toc13
SPKR_EN
2V/div
SPKR_EN
2V/div
SPEAKER OUT
SPEAKER OUT
200µs/div
200µs/div
WIDEBAND OUTPUT SPECTRUM
(SPEAKER MODE)
OUTPUT FREQUENCY SPECTRUM
(SPEAKER MODE)
0
-10
0
-20
V
= -60dBV
OUT
f = 1kHz
-20
R = 8Ω
L
-30
UNWEIGHTED
-40
-40
-50
-60
-60
-80
-70
-80
-100
-120
-140
-90
-100
-110
-120
RBW = 1kHz
INPUT AC GROUNDED
0
1
10
100
1
5
10
15
20
FREQUENCY (MHz)
FREQUENCY (kHz)
_______________________________________________________________________________________
9
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
HEADPHONE
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
-50
-60
-50
-60
-50
-60
R = 16Ω
V
= 3V
R = 32Ω
L
V = -3dBFS
IN
L
HPVDD
L
IN
V
IN
= -3dBFS
R = 16Ω
V
= -3dBFS
FS = 300mV
RMS
-70
-70
-70
FS = 300mV
RMS
FS = 300mV
RMS
-80
-80
-80
FS = 1V
FS = 1V
RMS
RMS
-90
-90
-90
FS = 1V
1
RMS
1/MAX792
-100
-100
-100
0.01
0.1
1
FREQUENCY (kHz)
10
100
0.01
0.1
1
10
100
0.01
0.1
10
100
FREQUENCY (kHz)
FREQUENCY (kHz)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
-50
-60
100
10
100
10
R = 16Ω
L
R = 32Ω
L
V
= 3V
HPVDD
R = 32Ω
L
V
IN
= -3dBFS
-70
1
1
FS = 300mV
RMS
f = 6kHz
f = 1kHz
f = 1kHz
-80
0.1
0.1
f = 100Hz
f = 6kHz
-90
0.01
0.001
0.01
0.001
FS = 1V
1
f = 100Hz
RMS
-100
100
OUTPUT POWER (mW)
200
0.01
0.1
10
100
0
40
80
OUTPUT POWER (mW)
120
160
200
0
50
150
250
FREQUENCY (kHz)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
OUTPUT POWER vs. LOAD RESISTANCE
(HEADPHONE MODE)
100
10
100
10
250
200
150
f = 1kHz
V
= 3V
V
= 3V
HPVDD
HPVDD
R = 16Ω
L
R = 32Ω
L
THD+N = 10%
1
1
THD+N = 1%
f = 100Hz
f = 1kHz
0.1
0.1
100
50
0
f = 1kHz
f = 6kHz
f = 100Hz
0.01
0.001
0.01
0.001
f = 6kHz
60
0
10 20 30 40 50 60 70 80 90
OUTPUT POWER (mW)
0
10
20
30
40
50
70
1
10
100
OUTPUT POWER (mW)
LOAD RESISTANCE (Ω)
10 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
HEADPHONE
OUTPUT POWER vs. LOAD RESISTANCE
(HEADPHONE MODE)
POWER DISSIPATION vs. OUTPUT POWER
(HEADPHONE MODE)
POWER DISSIPATION vs. OUTPUT POWER
(HEADPHONE MODE)
90
80
70
60
50
400
350
300
250
200
150
100
50
300
250
200
150
100
V
= 3V
HPVDD
V
= 3V
HPVDD
R = 16Ω
L
f = 1kHz
R = 16Ω
L
THD+N = 10%
THD+N = 1%
R = 32Ω
L
40
30
20
10
0
R = 32Ω
L
50
0
0
10
100
1000
0
25 50 75 100 125 150 175 200
PER CHANNEL OUTPUT POWER (mW)
0
20
40
60
80
100
LOAD RESISTANCE (Ω)
PER CHANNEL OUTPUT POWER (mW)
HEADPHONE OUTPUT POWER
vs. HPVDD
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY (HEADPHONE MODE)
CROSSTALK vs. FREQUENCY
(HEADPHONE MODE)
250
200
150
100
50
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-20
-30
-40
-50
-60
-70
-80
-90
-100
THD+N = 1%
f = 1kHz
R = 32Ω
FS = 300mV
L
V
= 200mV
RIGHT TO LEFT
COM AND SENSE
DISABLED
RIPPLE
P-P
RMS
R = 32Ω
L
V
IN
= -20dBFS
RIGHT TO LEFT
COM AND SENSE
DISABLED
R = 32Ω
L
RIGHT
RIGHT TO LEFT
COM AND SENSE
R = 16Ω
L
LEFT TO RIGHT
COM AND SENSE
LEFT
10
0
-120
2.5
3.0
3.5
4.0
HPVDD (V)
4.5
5.0
5.5
0.01
0.1
1
100
0.01
0.1
1
10
100
FREQUENCY (kHz)
FREQUENCY (kHz)
______________________________________________________________________________________ 11
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
HEADPHONE
OUTPUT FREQUENCY SPECTRUM
STARTUP WAVEFORM
(HEADPHONE MODE)
MAX9791 toc33
RIGHT AND LEFT
FS = 707mV
0
-20
RMS
V
= -60dBFS
IN
R = 32Ω
L
-40
HP_EN
2V/div
-60
-80
HP_
500mV/div
-100
1/MAX792
-120
-140
200µs/div
0
5
10
FREQUENCY (kHz)
15
20
HEADPHONE RF IMMUNITY
vs. FREQUENCY
SHUTDOWN WAVEFORM
MAX9791 toc34
R = 32Ω
L
-10
-30
HP_EN
2V/div
-50
LEFT
-70
HP_
500mV/div
-90
RIGHT
1000
-110
-130
200µs/div
500
1500
2000
2500
3000
FREQUENCY (MHz)
12 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
LINE OUT
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
0
-10
-20
-30
-40
-50
-60
0
-10
-20
-30
-40
-50
-60
100
10
R = 10kΩ
V
= 3V
R = 10kΩ
L
L
HPVDD
V
= -3dBFS
R = 10kΩ
IN
L
V
= -3dBFS
IN
1
f = 6kHz
0.1
f = 100Hz
FS = 707mV
FS = 1V
FS = 707mV
FS = 1V
RMS
-70
-80
-70
-80
RMS
RMS
RMS
0.01
0.001
0.0001
-90
-90
f = 1kHz
-100
-110
-100
-110
0.01
0.1
1
10
100
0.01
0.1
1
10
100
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
OUTPUT POWER (mW)
FREQUENCY (kHz)
FREQUENCY (kHz)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
CROSSTALK vs. FREQUENCY
(HEADPHONE MODE)
OUTPUT FREQUENCY SPECTRUM
(HEADPHONE MODE)
100
10
-20
-30
R = 10kΩ
L
V
= 3V
RIGHT AND LEFT
0
-20
HPVDD
FS = 707mV
RMS
R = 10kΩ
L
R = 10kΩ
L
V
IN
= -20dBFS
FS = 300mV
-40
RMS
V
= -60dBFS
IN
-50
1
-40
-60
-60
RIGHT TO LEFT
COM AND SENSE
0.1
-70
f = 6kHz
f = 100Hz
-80
-80
0.01
0.001
0.0001
-90
-100
-100
-110
-120
LEFT TO RIGHT
COM AND SENSE
-120
-140
f = 1kHz
0
0.5
1.0
1.5
2.0
2.5
3.0
0.01
0.1
1
10
100
0
5
10
15
20
OUTPUT POWER (mW)
FREQUENCY (kHz)
FREQUENCY (kHz)
______________________________________________________________________________________ 13
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
GENERAL
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
8
20
15
10
5
20
15
10
5
LDO_EN = 1
LDO_EN = 1, V
= 3.3V OR 4.75V
SPKR_EN = 1
HP_EN = 0
LDO_EN = 0
LDO
SPKR_EN = 0
V
= 1.8V
7
6
5
4
3
2
1
0
LDO_OUT
SPKR_EN = 0
HP_EN = 0
SPKR_EN = 0
HP_EN = 1
SPKR_EN = 1
SPKR_EN = 0
0
0
1/MAX792
SPKR_EN = 1
HP_EN = 0
SPKR_EN = 1
HP_EN = 1
SPKR_EN = 1
-5
-5
4.50
4.75
5.00
5.25
5.50
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
14 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
LDO
LDO OUTPUT ACCURACY
vs. LOAD CURRENT
LDO OUTPUT ACCURACY
vs. AMPLIFIER OUTPUT POWER
LDO OUTPUT ACCURACY
vs. TEMPERATURE
1.0
0.5
0
2.0
1.5
0.10
0.09
0.08
0.07
V
= 1.8V
LDO_OUT
1.0
0.5
0
V
= 3.3V
LDO_OUT
0.06
0.05
0.04
0.03
0.02
0.01
-0.5
V
= 4.75V
LDO_OUT
-0.5
-1.0
-1.0
-1.5
-2.0
0
-40
-15
10
35
60
85
0
25
50
75
100
125
150
0
300
600
900
1200
1500
TEMPERATURE (°C)
LOAD CURRENT (mA)
AMPLIFIER OUTPUT POWER (mW)
LDO POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
LDO DROPOUT VOLTAGE vs. LOAD
LDO OUTPUT NOISE
40
20
200
175
150
125
100
75
300
250
200
150
100
50
C
LOAD
= 2 x 1µF
= 120mA
V
I
= 200mV
P-P
= 10mA
LDO_OUT = 4.75V
RIPPLE
LOAD
I
LOAD
0
-20
-40
-60
-80
-100
V
= 3.3V
LDO_OUT
V
= 4.75V
LDO_OUT
V
= 1.8V
10
LDO_OUT
1
0
50
0
50
100
150
(mA)
200
250
300
0.01
0.1
100
0.01
0.1
1
10
100
I
FREQUENCY (kHz)
FREQUENCY (kHz)
LOAD
______________________________________________________________________________________ 15
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Typical Operating Characteristics (continued)
(V
= V
= V
IN1
= 5V, V
= V
= V
= 0, I
= 0, C
= 2 x 1µF, C1 = C2 = 1µF. R = ∞, unless oth-
LDO L
AVDD
PVDD
HPVDD
GND
PGND
CPGND
LDO_OUT
erwise specified. R
= 20kΩ (A
= 12dB), R
= 40.2kΩ (A
= 0dB), C
= 470nF, C
= C
= 1µF, measurement BW
COM
VSPKR
IN2
VHP
IN1
IN2
= 20kHz AES17, T = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,
A
HP_EN = 1.)
LDO
LINE-TRANSIENT RESPONSE
LOAD-TRANSIENT RESPONSE
MAX9791 toc51
MAX9791 toc50
I
LDO_OUT
CH1 LOW
4.560V
50mA/div
CH1 HIGH
5.500V
CH2 LOW
800.0µV
AC-COUPLED
V
LDO_OUT
CH2 HIGH
1.000mV
9
10mV/div
1.00ms/div
100ms/div
CROSSTALK vs. FREQUENCY
SPEAKER TO LDO
SHUTDOWN RESPONSE
MAX9791 toc52
0
-10
-20
-30
-40
BOTH SPEAKERS WITH SIGNAL
P
R
= 1.2W
SPKR
= 8W
LSPKR
I
= 10mA
LDO
-50
-60
LEFT CHANNEL TO LDO
LDO_EN
2V/div
-70
-80
-90
-100
-110
-120
-130
RIGHT CHANNEL TO LDO
V
LDO_EN
2V/div
200µs/div
0.01
0.1
1
10
100
FREQUENCY (kHz)
16 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
MAX9791 Pin Description
PIN
1
NAME
FUNCTION
SPKR_INL Left-Channel Speaker Amplifier Input
2
HP_INR
HP_INL
COM
Right-Channel Headphone Amplifier Input
Left-Channel Headphone Amplifier Input
Common-Mode Voltage Sense Input
Signal Ground. Star connect to PGND.
3
4
5
GND
LDO Output. Bypass the MAX9791A/MAX9791B with two 1µF ceramic low ESR capacitors to GND.
Bypass the MAX9791C with two 2µs ceramic low ESR capacitors to GND.
6
LDO_OUT
7
8
AVDD
LDO_EN
HPR
Positive Power-Supply and LDO Input. Bypass with a 0.1µF and two 1µF capacitors to GND.
LDO Enable. Connect LDO_EN to AVDD to enable the LDO.
Right-Channel Headphone Amplifier Output
9
10
HPL
Left-Channel Headphone Amplifier Output
11
SENSE
CPVSS
C1N
Headphone Ground Sense
12
Headphone Amplifier Negative Power Supply. Connect a 1µF capacitor between CPVSS and PGND.
Charge-Pump Flying Capacitor Negative Terminal. Connect a 1µF capacitor between C1P and C1N.
Charge-Pump Ground. Connect directly to PGND plane.
13
14
CPGND
C1P
15
Charge-Pump Flying Capacitor Positive Terminal. Connect a 1µF capacitor between C1P and C1N.
Headphone Amplifier Positive Power Supply. Connect a 10µF capacitor between HPVDD and PGND.
Speaker Amplifier Power-Supply Input. Bypass with a 0.1µF capacitor to PGND.
Left-Channel Speaker Amplifier Output, Negative Phase
16
HPVDD
PVDD
OUTL-
OUTL+
PGND
BEEP
17, 26
18
19
Left-Channel Speaker Amplifier Output, Positive Phase
20, 23
21
Power Ground. Star connect to GND.
PC Beep Input. Connect to GND if beep detection function is disabled.
Active-High Headphone Amplifier Enable
22
HP_EN
OUTR+
OUTR-
24
Right-Channel Speaker Amplifier Output, Positive Phase
25
Right-Channel Speaker Amplifier Output, Negative Phase
27
SPKR_EN Active-Low Speaker Amplifier Enable
28
SPKR_INR Right-Channel Speaker Amplifier Input
—
EP
Exposed Pad. Connect to GND.
______________________________________________________________________________________ 17
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
MAX9792 Pin Description
PIN
1, 5
2
NAME
GND
FUNCTION
Signal Ground. Star connect to PGND.
Right-Channel Headphone Amplifier Input
Left-Channel Headphone Amplifier Input
Common-Mode Voltage Sense Input
HP_INR
HP_INL
COM
3
4
6
LDO_OUT LDO Output. Bypass with two 1µF ceramic low ESR capacitors to GND.
AVDD Positive Power Supply and LDO Input. Bypass with a 0.1µF and two 1µF capacitors to GND.
LDO_EN LDO Enable. Connect LDO_EN to AVDD to enable the LDO.
7
8
9
HPR
HPL
Right-Channel Headphone Amplifier Output
10
Left-Channel Headphone Amplifier Output
11
SENSE
CPVSS
C1N
Headphone Ground Sense
12
Headphone Amplifier Negative Power Supply. Connect a 1µF capacitor between CPVSS and PGND.
Charge-Pump Flying Capacitor Negative Terminal. Connect a 1µF capacitor between C1P and C1N.
Charge-Pump Ground. Connect directly to PGND plane.
13
14
CPGND
C1P
1/MAX792
15
Charge-Pump Flying Capacitor Positive Terminal. Connect a 1µF capacitor between C1P and C1N.
Headphone Amplifier Positive Power Supply. Connect a 10µF capacitor between HPVDD and PGND.
Speaker Amplifier Power-Supply Input. Bypass with a 0.1µF capacitor to PGND.
Speaker Amplifier Output, Negative Phase
16
HPVDD
PVDD
OUT-
17, 26
18, 25
19, 24
20, 23
21
OUT+
PGND
BEEP
HP_EN
Speaker Amplifier Output, Positive Phase
Power Ground. Star connect to GND.
PC Beep Input. Connect to GND if beep detection function is disabled.
Active-High Headphone Amplifier Enable
22
27
SPKR_EN Active-Low Speaker Amplifier Enable
28
SPKR_IN Speaker Amplifier Input
—
EP
Exposed Pad. Connect to GND.
The MAX9791/MAX9792 feature spread-spectrum mod-
ulation and active emission limiting circuitry that offers
significant improvements to switch-mode amplifier tech-
nology. These devices offer Class AB performance with
Class D efficiency in a minimal board-space solution.
Detailed Description
The MAX9791 combines a stereo 2W Class D power
amplifier, a stereo 175mW DirectDrive headphone
amplifier, and a 120mA LDO linear regulator in a single
device. The MAX9792 combines a mono 3W Class D
power amplifier, a stereo 175mW DirectDrive head-
phone amplifier, and a 120mA LDO linear regulator in a
single device.
The headphone amplifiers use Maxim’s DirectDrive
architecture to eliminate the bulky output DC-blocking
capacitors required by traditional headphone ampli-
fiers. A charge pump inverts the positive supply
(HPVDD) to create a negative supply (CPVSS). The
headphone amplifiers operate from these bipolar sup-
plies with their outputs biased about GND. The bene-
fit of the GND bias is that the amplifier outputs no
The MAX9791/MAX9792 feature wake-on-beep detec-
tion, comprehensive click-and-pop suppression, low-
power shutdown mode, and excellent RF immunity.
These devices incorporate an integrated LDO that
serves as a clean power supply for CODEC or other cir-
cuits. The MAX9791/MAX9792 are Windows Vista
Premium compliant. See Table 1 for a comparison of the
Windows Vista Premium specifications and MAX9791/
MAX9792 specifications.
longer have a DC component (typically V /2). This
DD
feature eliminates the large DC-blocking capacitors
required with conventional headphone amplifiers to
18 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
Table 1. Windows Premium Mobile Vista Specifications vs. MAX9791/MAX9792
Specifications
WINDOWS PREMIUM
MAX9791/MAX9792
DEVICE TYPE
REQUIREMENT
THD+N
MOBILE VISTA
TYPICAL PERFORMANCE
SPECIFICATIONS
≤ -65dB FS [100Hz, 20kHz]
87dBFS [100Hz, 20kHz]
Analog Line-Out Jack
(R = 10kΩ, FS =
Dynamic range with signal ≤ -80dBV, A-weighted [20Hz,
-98.9dB A-weighted [20Hz, 20kHz]
L
present
20kHz]
0.707V
)
RMS
Line output crosstalk
THD+N
≤ -50dB [20Hz, 15kHz]
≤ -45dB FS [100Hz, 20kHz]
64dB [20Hz, 15kHz]
82dBFS [100Hz, 20kHz]
Dynamic range with signal ≤ -60dBV, A-weighted [20Hz,
Analog Headphone-Out
Jack (R = 32Ω, FS =
-91.5dB A-weighted [20Hz, 20kHz]
64dB [20Hz, 15kHz]
present
20kHz]
L
0.300V
)
RMS
Headphone output
crosstalk
≤ -50dB [20Hz, 15kHz]
Note: THD+N, dynamic range with signal present, and crosstalk should be measured in accordance with AES17 audio measure-
ments standards.
conserve board space and system cost, as well as
improve low-frequency response and distortion.
EFFICIENCY vs. IDEAL
CLASS AB EFFICIENCY
The MAX9791/MAX9792 amplifiers feature an under-
voltage lockout that prevents operation from an insuffi-
cient power supply and click-and-pop suppression that
eliminates audible transients on startup and shutdown.
The amplifiers include thermal overload and short-cir-
cuit protection.
90
80
70
60
50
40
30
20
10
0
MAX9791
Class D Speaker Amplifier
The MAX9791/MAX9792 integrate a filterless class D
amplifier that offers much higher efficiency than class AB
amplifiers. The high efficiency of a Class D amplifier is
due to the switching operation of the output stage tran-
sistors. In a Class D amplifier, the output transistors act
as current steering switches and consume negligible
additional power. Any power loss associated with the
Class D output stage is mostly due to the I2R loss of the
MOSFET on-resistance and quiescent current overhead.
IDEAL CLASS AB
0
0.25 0.50 0.75 1.00 1.25 1.50
OUTPUT POWER (W)
Figure 1. MAX9791 Efficiency vs. Class AB Efficiency
The theoretical best efficiency of a linear amplifier is
78%, however, that efficiency is only exhibited at peak
output power. Under normal operating levels (typical
music reproduction levels), efficiency falls below 45%,
whereas the MAX9791/MAX9792 exhibit 67% efficiency
under the same conditions (Figure 1).
Ultra-Low EMI Filterless Output Stage
In traditional Class D amplifiers, the high dv/dt of the
rising and falling edge transitions resulted in increased
electromagnetic-interference (EMI) emissions, which
required the use of external LC filters or shielding to
meet EN55022B EMI regulation standards. Limiting the
dv/dt normally results in decreased efficiency. Maxim’s
active emissions limiting circuitry actively limits the
dv/dt of the rising and falling edge transitions, providing
reduced EMI emissions while maintaining up to 83%
efficiency.
______________________________________________________________________________________ 19
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
V
DD
CLASS D EMI PLOT
40
35
30
25
20
15
10
5
EN55022B LIMIT
V
OUT
V /2
DD
GND
CONVENTIONAL AMPLIFIER BIASING SCHEME
+V
DD
30
100
1000
FREQUENCY (MHz)
V
OUT
GND
Figure 2. EMI with 30cm of Speaker Cable
1/MAX792
In addition to active emission limiting, the MAX9791/
MAX9792 feature spread-spectrum modulation that flat-
tens the wideband spectral components. Proprietary
techniques ensure that the cycle-to-cycle variation of the
switching period does not degrade audio reproduction
or efficiency (see the Typical Operating Characteristics).
In spread-spectrum modulation mode, the switching fre-
quency varies randomly by 15kHz around the center
frequency (530kHz). The effect is to reduce the peak
energy at harmonics of the switching frequency. Above
10MHz, the wideband spectrum looks like noise for EMI
purposes (see Figure 2).
-V
DD
DirectDrive AMPLIFIER BIASING SCHEME
Figure 3. Traditional Amplifier Output vs. MAX9791/MAX9792
DirectDrive Output
Maxim’s DirectDrive architecture uses a charge pump
to create an internal negative supply voltage. This
allows the headphone outputs of the MAX9791/
MAX9792 to be biased at GND while operating from a
single supply (Figure 3). Without a DC component,
there is no need for the large DC-blocking capacitors.
Instead of two large (220µF, typ) capacitors, the
MAX9791/MAX9792 charge pump requires two small
1µF ceramic capacitors, conserving board space,
reducing cost, and improving the frequency response
of the headphone amplifier.
Speaker Current Limit
When the output current of the speaker amplifier
exceeds the current limit (2A, typ) the MAX9791/
MAX9792 disable the outputs for approximately 100µs.
At the end of 100µs, the outputs are re-enabled. If the
fault condition still exists, the MAX9791/MAX9792 con-
tinue to disable and re-enable the outputs until the fault
condition is removed.
The MAX9791/MAX9792 feature a low-noise charge
pump. The nominal switching frequency of 530kHz is
well beyond the audio range, and thus does not inter-
fere with audio signals. The switch drivers feature a
controlled switching speed that minimizes noise gener-
ated by turn-on and turn-off transients. By limiting the
switching speed of the charge pump, the di/dt noise
caused by the parasitic trace inductance is minimized.
DirectDrive Headphone Amplifier
Traditional single-supply headphone amplifiers bias the
outputs at a nominal DC voltage (typically half the sup-
ply). Large coupling capacitors are needed to block
this DC bias from the headphone. Without these capac-
itors, a significant amount of DC current flows to the
headphone, resulting in unnecessary power dissipation
and possible damage to both headphone and head-
phone amplifier.
20 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
R
FHP
CROSSTALK
vs. GROUND RESISTANCE (RG)
C
IN2
-40
-45
-50
-55
-60
-65
-70
-75
-80
HP_INL
COM
R = 5Ω
R = 32Ω
L
S
HPL
R
IN2
HPR
C
COM
R
FHP
SENSE
R
COM
C
IN2
HP_INR
R
IN2
0
0.025 0.050 0.075 0.100 0.125 0.150
RG (Ω)
R
FHP
Figure 4. Connecting COM for Ground Sense
Figure 5. Crosstalk vs. Ground Resistance
Common-Mode Sense
Windows Vista-compliant platforms are restricted to only
115mΩ of ground return impedance. If the headphone
jack ground is connected close to the audio device
ground using a solid ground plane, the return path resis-
tance can be quite low. However, it is often necessary to
locate some jacks far from the audio device. The
MAX9791/MAX9792 COM and SENSE inputs allow the
headphone jack to be placed further away from the
device without degrading crosstalk performance.
The headphone amplifier output impedance, trace
resistance, and contact resistance of the jack are
grouped together to represent the source resistance,
R . The resistance between the load and the sleeve,
S
the sleeve contact resistance, and the system ground
return resistance are grouped together to represent the
ground resistance, R .
G
Assuming a typical source resistance of 5Ω, the ground
return impedance would need to be limited to 115mΩ
to meet Windows Vista’s crosstalk specification of 50dB
(Figure 5). This is further complicated by the fact that
the impedance of the sleeve connection in the 3.5mm
stereo jack can make up 30mΩ–90mΩ alone.
The MAX9791/MAX9792 COM and SENSE inputs
reduce crosstalk performance by eliminating effects of
28.5mΩ of ground return path resistance. If ground
sensing is not required, connect COM directly to GND
and leave SENSE unconnected (Figure 6).
The MAX9791/MAX9792 SENSE and COM inputs sense
and correct for the difference between the headphone
return and device ground. When using common-mode
sense, connect COM through a resistor to GND of the
device (Figure 4). For optimum common-mode rejec-
tion, use the same value resistors for R
and R
.
IN2
COM
To improve AC CMRR, add a capacitor equal to C
IN2
between GND and R
.
COM
Configuring SENSE and COM in this way improves sys-
tem crosstalk performance by reducing the negative
effects of the headphone jack ground return resistance.
Wake-on-Beep
The MAX9791/MAX9792 beep-detection circuit wakes
up the device (speaker and headphone amplifiers)
once a qualified beep signal is detected at BEEP and
the LDO is enabled. The amplifier wake command from
the beep-detection circuit overrides the logic signal
applied at HP_EN and SPKR_EN.
⎛
⎞
⎟
R
G
Crosstalk in dB = 20 log
⎜
R
+ R
S
⎝
⎠
L
______________________________________________________________________________________ 21
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
A qualified BEEP signal consists of a 3.3V typical,
215Hz minimum signal that is present at BEEP for four
consecutive cycles. Once the first rising edge transition
is detected at BEEP, the beep circuit wakes up and
begins counting the beep cycles. Once four consecu-
tive cycles of a qualified beep signal are counted, the
device (speaker and headphone amplifiers) enables
within 400µs. If the first rising edge is not followed by
three consecutive rising edges within 16ms, the device
remains shutdown (i.e., glitch protection).
CROSSTALK vs. FREQUENCY
(HEADPHONE MODE)
-20
-30
-40
-50
-60
-70
-80
-90
-100
R = 32Ω
L
RIGHT TO LEFT
COM AND SENSE
DISABLED
FS = 300mV
RMS
V
= -20dBFS
OUT
LEFT TO RIGHT
COM AND SENSE
DISABLED
RIGHT TO LEFT
COM AND SENSE
The device (speaker and headphone amplifiers) returns
to its programmed logic state once 246ms has elapsed
from the time the last rising edge was detected. This
246ms amplifier hold time ensures complete beep pro-
files are passed to the amplifier outputs (Figure 7).
Ground BEEP when the wake-on-beep feature is not
used. Do not leave BEEP unconnected.
LEFT TO RIGHT
COM AND SENSE
0.01
0.1
1
10
100
FREQUENCY (kHz)
Low-Dropout Linear Regulator
The LDO regulator can be used to provide a clean
power supply to a CODEC or other circuitry. The LDO
can be enabled independently of the audio amplifiers.
Set LDO_EN = AVDD to enable the LDO or set LDO_EN
= GND to disable the LDO. The LDO can provide up to
120mA of continuous current.
1/MAX792
Figure 6. MAX9791/MAX9792 COM and SENSE Inputs Reduce
Crosstalk
time, connect SPKR_EN and HP_EN together, allowing
a single logic voltage to enable either the speaker or
the headphone amplifier as shown in Figure 8.
Speaker and Headphone Amplifier Enable
The MAX9791/MAX9792 feature control inputs for the
independent enabling of the speaker and headphone
amplifiers, allowing both to be active simultaneously
if required. Driving SPKR_EN high disables the speaker
amplifiers. Driving HP_EN low independently disables
the headphone amplifiers. For applications that
require only one of the amplifiers to be on at a given
Shutdown
The MAX9791/MAX9792 feature a low-power shutdown
mode, drawing 3.3µA of supply current. By disabling
the speaker, headphone amplifiers, and the LDO, the
MAX9791/MAX9792 enter low-power shutdown mode.
Set SPKR_EN to AVDD and HP_EN and LDO_EN to
GND to disable the speaker amplifiers, headphone
amplifiers, and LDO, respectively.
16ms
BEEP
1
2
4
3
240ms
SPKR AND HP
AMPS ENABLE
400µs
Figure 7. Qualified BEEP Signal Timing
22 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
MAX9791
R
FB
MAX9791
MAX9792
20kΩ
MONO
CLASS D
AMPLIFIER
OUT_+
OUT_-
SINGLE
CONTROL
C
IN1
SPKR_EN
HP_EN
R
IN1
SPKR_IN_
Figure 8. Enabling Either the Speaker or Headphone Amplifier
with a Single Control Pin
Figure 9. Setting Speaker Amplifier Gain
Click-and-Pop Suppression
The MAX9791/MAX9792 feature a common-mode bias
voltage of 0V. A 0V BIAS allows the MAX9791/MAX9792
to quickly turn on/off with no resulting clicks and pops.
With the HDA CODEC outputs biased and the
MAX9791/MAX9792 inputs sitting as 0V in shutdown
Applications Information
Filterless Class D Operation
Traditional Class D amplifiers require an output filter to
recover the audio signal from the amplifier’s output. The
filters add cost and size and can decrease efficiency
and THD+N performance. The traditional PWM scheme
uses large differential output swings (2 x PVDD peak-
to-peak) causing large ripple currents. Any parasitic
resistance in the filter components results in a loss of
power, lowering the efficiency.
and normal operation, the R x C time constant is
IN
IN
eliminated.
Speaker Amplifier
The MAX9791/MAX9792 speaker amplifiers feature
Maxim’s comprehensive, industry leading click-and-
pop suppression. During startup and shutdown, the
click-and-pop suppression circuitry eliminates any
audible transient sources internal to the device.
The MAX9791/MAX9792 do not require an output filter.
The devices rely on the inherent inductance of the speak-
er coil and the natural filtering of both the speaker and
the human ear to recover the audio component of the
square-wave output. Eliminating the output filter results in
a smaller, less costly, and more efficient solution.
Headphone Amplifier
In conventional single-supply headphone amplifiers,
the output-coupling capacitor is a major contributor of
audible clicks and pops. Upon startup, the amplifier
charges the coupling capacitor to its bias voltage, typi-
Because the frequency of the MAX9791/MAX9792 out-
put is well beyond the bandwidth of most speakers,
voice coil movement due to the square-wave frequency
is very small. For optimum results, use a speaker with a
series inductance > 10µH. Typical 8Ω speakers exhibit
series inductances in the 20µH to 100µH range.
cally V /2. During shutdown, the capacitor is dis-
DD
charged to GND; a DC shift across the capacitor
results, which in turn appears as an audible transient at
the speaker. Because the MAX9791/MAX9792 do not
require output-coupling capacitors, no audible transient
occurs.
The MAX9791/MAX9792 headphone amplifiers feature
extensive click-and-pop suppression that eliminates
any audible transient sources internal to the device.
______________________________________________________________________________________ 23
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Setting Speaker Amplifier Gain
External input resistors in conjunction with the internal
L1*
feedback resistors (R
) set the speaker amplifier
FSPKR
MAX9791
MAX9792
gain of the MAX9791/MAX9792. Set gain by using
resistor R
as follows (Figure 9):
IN1
L2*
⎛
⎝
⎞
⎠
20kΩ
A
= -4
V / V
330pF
330pF
VSPKR
⎜
⎟
R
IN1
where A
is the desired voltage gain. An R
of
VSPKR
IN1
*L1 = L2 = WÜRTH 742792040
20kΩ yields a gain of 4V/V, or 12dB.
Figure 10. Optional Ferrite Bead Filter
Component Selection
Optional Ferrite Bead Filter
In applications where speaker leads exceed 15cm, use
a filter constructed from a ferrite bead and a capacitor
to ground (Figure 10) to provide additional EMI sup-
pression. Use a ferrite bead with low DC resistance,
high frequency (> 1.2MHz) impedance of 100Ω to
600Ω, and rated for at least 1A. The capacitor value
varies based on the ferrite bead chosen and the actual
speaker lead length. Select the capacitor value based
on EMI performance.
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
100
10
R = 32Ω
L
1/MAX792
OUT OF PHASE
IN PHASE
1
0.1
Output Power (Headphone Amplifier)
The headphone amplifiers are specified for the worst-
case scenario when both inputs are in phase. Under
this condition, the drivers simultaneously draw current
from the charge pump, leading to a slight loss in head-
room of CPVSS. In typical stereo audio applications, the
left and right signals have differences in both magni-
tude and phase, subsequently leading to an increase in
the maximum attainable output power. Figure 11 shows
the two extreme cases for in and out of phase. In most
cases, the available power lies between these
extremes.
0.01
0.001
0
50
100
150
200
250
OUTPUT POWER (mW)
Figure 11. Output Power vs. Supply Voltage with Inputs In/Out
of Phase; 32Ω Load Conditions and 3.5dB Gain
Power Supplies
The MAX9791/MAX9792 speaker amplifiers are pow-
ered from PVDD with a range from 2.7V to 5.5V. The
headphone amplifiers are powered from HPVDD and
CPVSS. HPVDD is the positive supply of the headphone
amplifiers and charge pump ranging from 2.7V to 5.5V.
CPVSS is the negative supply of the headphone ampli-
fiers. The charge pump inverts the voltage at HPVDD,
and the resulting voltage appears at CPVSS. AVDD
powers the LDO and the remainder of the device.
AVDD and PVDD must be tied together. If LDO is
enabled, set AVDD and PVDD as specified in the Line
Regulation row of the Electrical Characteristics table.
Headphone Amplifier Gain
Gain-Setting Resistors
External input resistors in conjunction with the internal
feedback resistors (R
) set the headphone amplifier
FHP
gain of the MAX9791/MAX9792. Set gain by using
resistor R
(Figure 4) as follows:
IN2
⎛
⎝
⎞
⎠
40.2kΩ
A
= -
V / V
VHP
⎜
⎟
R
IN2
where A
is the desired voltage gain. An R
of
IN2
VHP
40.2kΩ yields a gain of 1V/V, or 0dB.
24 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
SPEAKER RF IMMUNITY
vs. FREQUENCY
INPUT COUPLING CAPACITOR-INDUCED THD+N
vs. FREQUENCY (HEADPHONE MODE)
-50
0
-10
-20
V
- -3dBFS
RMS
OUT
0402 6.3V X5R 10% 1µF
FS = 1V
R =32Ω
L
-60
-30
-40
-50
RIGHT
-70
0603 10V X5R 10% 1µF
0805 50V X7R 10% 1µF
-60
-70
-80
-90
-100
-110
-120
-130
-80
LEFT
-90
0603 10V X7R 10% 1µF
-100
10
100
1000
0
500 1000 1500 2000 2500 3000
FREQUENCY (MHz)
FREQUENCY (kHz)
Figure 12. Input Coupling Capacitor-Induced THD+N vs.
Frequency
Figure 13. Speaker RF Immunity
Input Filtering
Component Selection
The input capacitor (C ), in conjunction with the ampli-
IN_
Speaker Amplifier Power-Supply Input (PVDD)
PVDD powers the speaker amplifiers. PVDD ranges
from 2.7V to 5.5V. AVDD and PVDD must be tied
together. If LDO is enabled, set AVDD and PVDD as
specified in the Line Regulation row of the Electrical
Characteristics table. Bypass PVDD with a 0.1µF
capacitor to PGND. Apply additional bulk capacitance
at the device if long input traces between PVDD and
the power source are used.
fier input resistance (R ), forms a highpass filter that
IN_
removes the DC bias from the incoming signal. The AC-
coupling capacitor allows the amplifier to bias the signal
to an optimum DC level. Assuming zero source imped-
ance, the -3dB point of the highpass filter is given by:
1
f
=
-3dB
2πR
C
IN_ IN_
R
is the amplifier’s external input resistance value.
IN_
Choose C
Headphone Amplifier Power-Supply Input
(HPVDD and CPVSS)
such that f
is well below the lowest
-3dB
IN_
frequency of interest. Setting f
too high affects
-3dB
The headphone amplifiers are powered from HPVDD
and CPVSS. HPVDD is the positive supply of the head-
phone amplifiers and ranges from 2.7V to 5.5V. Bypass
HPVDD with a 10µF capacitor to PGND. CPVSS is the
negative supply of the headphone amplifiers. Bypass
CPVSS with a 1µF capacitor to PGND. The charge
pump inverts the voltage at HPVDD, and the resulting
voltage appears at CPVSS. A 1µF capacitor should be
connected between C1N and C1P.
the amplifier’s low frequency response. Use capaci-
tors with adequately low-voltage coefficients (see
Figure 12). Capacitors with higher voltage coeffi-
cients, such as ceramics, result in increased distor-
tion at low frequencies.
Charge-Pump Capacitor Selection
Use capacitors with an ESR less than 100mΩ for opti-
mum performance. Low ESR ceramic capacitors mini-
mize the output resistance of the charge pump. For
best performance over the extended temperature
range, select capacitors with an X7R dielectric.
Positive Power Supply and LDO Input (AVDD)
The internal LDO and the remainder of the device are
powered by AVDD. AVDD ranges from 2.7V to 5.5V.
AVDD and PVDD must be tied together. If LDO is
enabled, set AVDD and PVDD as specified in LDO line
regulation. Bypass AVDD with a 0.1µF capacitor to
GND and two 1µF capacitors to GND. Note additional
bulk capacitance is required at the device if long input
traces between AVDD and the power source are used.
Flying Capacitor (C1)
The value of the flying capacitor (C1) affects the load
regulation and output resistance of the charge pump. A
C1 value that is too small degrades the device’s ability
to provide sufficient current drive, which leads to a loss
of output voltage. Connect a 1µF capacitor between
C1P and C1N.
______________________________________________________________________________________ 25
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Charge-Pump Output Capacitor (C2)
The MAX9791/MAX9792 is inherently designed for
excellent RF immunity. For best performance, add
ground fills around all signal traces on top or bottom
PCB planes.
Connect a 1µF capacitor between CPVSS and PGND.
LDO Output Capacitor (CLDO)
Connect 2 x 1µF capacitors between LDO_OUT and
GND for 4.75V and 3.3V LDO options (MAX979_A and
MAX979_B, respectively). Connect two parallel 2µF
capacitors between LDO_OUT and GND for the 1.8V
LDO option (MAX979_C).
Use large, low-resistance output traces. As load imped-
ance decreases, the current drawn from the device out-
puts increase. At higher current, the resistance of the
output traces decrease the power delivered to the load.
For example, if 2W is delivered from the speaker output
to a 4Ω load through a 100mΩ trace, 49mW is wasted
in the trace. If power is delivered through a 10mΩ
trace, only 5mW is wasted in the trace. Large output,
supply, and GND traces also improve the power dissi-
pation of the device.
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Use large traces for the power-supply
inputs and amplifier outputs to minimize losses due to
parasitic trace resistance, as well as route heat away
from the device. Good grounding improves audio per-
formance, minimizes crosstalk between channels, and
prevents switching noise from coupling into the audio
signal. Connect PGND and GND together at a single
point on the PCB. Route PGND and all traces that carry
switching transients away from GND, and the traces
and components in the audio signal path.
The MAX9791/MAX9792 thin QFN package features an
exposed thermal pad on its underside. This pad lowers
the package’s thermal resistance by providing a direct
heat conduction path from the die to the printed circuit
board. Connect the exposed thermal pad to GND by
using a large pad and multiple vias to the GND plane.
1/MAX792
Chip Information
Connect C2 to the PGND plane. Place the charge-
pump capacitors (C1, C2) as close as possible to the
device. Bypass PVDD with a 0.1µF capacitor to PGND.
Place the bypass capacitors as close as possible to the
device.
PROCESS: BiCMOS
26 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
Pin Configurations
TOP VIEW
TOP VIEW
21 20 19 18 17 16 15
21 20 19 18 17 16 15
14
13
14
13
HP_EN 22
PGND 23
CPGND
C1N
HP_EN 22
PGND 23
CPGND
C1N
12 CPVSS
12 CPVSS
24
25
26
27
28
24
25
26
27
28
OUTR+
OUTR-
OUT+
OUT-
SENSE
HPL
SENSE
HPL
11
10
9
11
10
9
MAX9791
MAX9792
PVDD
PVDD
*EP
*EP
HPR
HPR
SPKR_EN
SPKR_INR
SPKR_EN
SPKR_IN
+
+
8
8
LDO_EN
LDO_EN
1
2
3
4
5
6
7
1
2
3
4
5
6
7
TQFN
TQFN
(4mm x 4mm x 0.75mm)
(4mm x 4mm x 0.75mm)
*EP = EXPOSED PAD
*EP = EXPOSED PAD
Simplified Block Diagrams
(continued)
SPEAKER AND LDO
SUPPLY
2.7V TO 5.5V
HEADPHONE SUPPLY
2.7V TO 5.5V
CLASS D
AMP
SPKR_IN
MAX9792
HP_INR
HP_INL
SPKR_EN
HP_EN
AVDD
LDO
LDO_EN
BEEP
1.8V OR 4.75V
______________________________________________________________________________________ 27
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
MAX9791A/MAX9791B Block Diagram
2.7V TO 5.5V
0.1µF
10µF
0.1µF
1.0µF
1.0µF
AVDD
PVDD
17, 26
7
MAX9791A
MAX9791B
C
C
IN3
R
IN3
20kΩ
19 OUTL+
18 OUTL-
IN1
RIN1
RIN1
SPKR_INL
1
STEREO
CLASS D
AMPLIFIER
CIN1
OUTR+
SPKR_INR 28
24
1/MAX792
25 OUTR-
C
IN3
R
IN3
20kΩ
C
IN2
R
IN2
40.2kΩ
HP_INL
HP_INR
3
2
C
TO HPVDD
IN2
R
IN2
10 HPL
2.7V TO 5.5V
TO CPVSS
LDO_EN
8
9
HPR
HP_EN 22
BEEP 21
CONTROL
µC BEEP INPUT
27
SPKR_EN
TO HPVDD
C
COM
R
COM
2.7V TO 5.5V
C3
SENSE
40.2kΩ
11
COM
4
40.2kΩ
16 HPVDD
15 C1P
10µF
C1
1.0µF
14 CPGND
CHARGE
PUMP
LDO_OUT
6
TO CODEC
LDO BLOCK
C1N
13
1.0µF
1.0µF
5
20, 23
PGND
12
NOTE: LOGIC PINS CONFIGURED FOR:
CPVSS
GND
LDO_EN = 1, LDO ENABLED
SPKR_EN = 0, SPEAKER AMPLIFIERS ENABLED
HP_EN = 1, HEADPHONE AMPLIFIER ENABLED
C2
1.0µF
28 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
MAX9791C Block Diagram
2.7V TO 5.5V
0.1µF
10µF
0.1µF
1.0µF
1.0µF
AVDD
PVDD
17, 26
7
C
C
MAX9791C
IN3
R
IN3
20kΩ
19 OUTL+
18 OUTL-
IN1
RIN1
RIN1
SPKR_INL
1
STEREO
CLASS D
AMPLIFIER
CIN1
OUTR+
SPKR_INR 28
24
25 OUTR-
C
IN3
R
IN3
20kΩ
C
IN2
R
IN2
40.2kΩ
HP_INL
HP_INR
3
2
C
TO HPVDD
IN2
R
IN2
10 HPL
2.7V TO 5.5V
TO CPVSS
LDO_EN
8
9
HPR
HP_EN 22
CONTROL
BEEP 21
µC BEEP INPUT
27
4
SPKR_EN
COM
TO HPVDD
C
COM
R
COM
2.7V TO 5.5V
C3
SENSE
40.2kΩ
11
40.2kΩ
16 HPVDD
15 C1P
10µF
C1
1.0µF
14 CPGND
CHARGE
PUMP
LDO_OUT
6
TO CODEC
LDO BLOCK
C1N
13
2.0µF
2.0µF
5
20, 23
PGND
12
NOTE: LOGIC PINS CONFIGURED FOR:
CPVSS
GND
LDO_EN = 1, LDO ENABLED
SPKR_EN = 0, SPEAKER AMPLIFIER ENABLED
HP_EN = 1, HEADPHONE AMPLIFIER ENABLED
C2
1.0µF
______________________________________________________________________________________ 29
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
MAX9792A Block Diagram
2.7V TO 5.5V
0.1µF
10µF
0.1µF
1.0µF
1.0µF
AVDD
PVDD
17, 26
7
MAX9792A
C
IN3
R
IN3
20kΩ
19, 24 OUT+
18, 25 OUT-
MONO
CLASS D
AMPLIFIER
C
IN1
RIN1
IN2
SPKR_IN 28
C
IN2
R
1/MAX792
40.2kΩ
TO HPVDD
HP_INL
HP_INR
3
2
C
IN2
R
IN2
10 HPL
2.7V TO 5.5V
TO CPVSS
LDO_EN
8
9
HPR
HP_EN 22
CONTROL
BEEP 21
µC BEEP INPUT
27
4
SPKR_EN
COM
TO HPVDD
C
COM
R
COM
2.7V TO 5.5V
C3
SENSE
40.2kΩ
11
40.2kΩ
16 HPVDD
15 C1P
10µF
C1
1.0µF
14 CPGND
CHARGE
PUMP
LDO_OUT
6
TO CODEC
LDO BLOCK
C1N
13
1.0µF
1.0µF
1, 5
20, 23
PGND
12
NOTE: LOGIC PINS CONFIGURED FOR:
CPVSS
GND
LDO_EN = 1, LDO ENABLED
SPKR_EN = 0, SPEAKER AMPLIFIER ENABLED
HP_EN = 1, HEADPHONE AMPLIFIER ENABLED
C2
1.0µF
30 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
MAX9792C Block Diagram
2.7V TO 5.5V
0.1µF
10µF
0.1µF
1.0µF
1.0µF
AVDD
PVDD
17, 26
7
MAX9792C
C
IN3
R
IN3
20kΩ
19, 24 OUT+
18, 25 OUT-
MONO
CLASS D
AMPLIFIER
C
IN1
RIN1
IN2
SPKR_IN 28
C
IN2
R
40.2kΩ
TO HPVDD
HP_INL
HP_INR
3
2
C
IN2
R
IN2
10 HPL
2.7V TO 5.5V
TO CPVSS
LDO_EN
8
9
HPR
HP_EN 22
BEEP 21
CONTROL
µC BEEP INPUT
27
SPKR_EN
COM
TO HPVDD
C
COM
R
COM
2.7V TO 5.5V
C3
SENSE
40.2kΩ
11
4
40.2kΩ
16 HPVDD
15 C1P
10µF
C1
1.0µF
14 CPGND
CHARGE
PUMP
LDO_OUT
6
TO CODEC
LDO BLOCK
C1N
13
2.0µF
2.0µF
1, 5
20, 23
PGND
12
NOTE: LOGIC PINS CONFIGURED FOR:
CPVSS
GND
LDO_EN = 1, LDO ENABLED
SPKR_EN = 0, SPEAKER AMPLIFIER ENABLED
HP_EN = 1, HEADPHONE AMPLIFIER ENABLED
C2
1.0µF
______________________________________________________________________________________ 31
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
21-0139
LAND PATTERN NO.
90-0068
28 TQFN-EP
T2844-1
1/MAX792
32 ______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
1/MAX792
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
______________________________________________________________________________________ 33
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
0
11/08
Initial release
Adding MAX9791C/MAX9792C versions
—
1–7, 10, 13–16,
19, 21–30
1
6/10
1/MAX792
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
34 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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