MAX13330GEEV [MAXIM]
Automotive DirectDrive Headphone Amplifiers with Output Protection and Diagnostics;
| 型号： | MAX13330GEEV |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Automotive DirectDrive Headphone Amplifiers with Output Protection and Diagnostics |
| 文件： | 总15页 (文件大小：393K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4341; Rev 3; 7/11
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
0/MAX31
General Description
Features
The MAX13330/MAX13331 stereo headphone amplifiers
are designed for automotive applications requiring out-
put short-circuit and ESD protection to battery/ground
with diagnostics. These devices use Maxim’s unique
♦ 4V to 5.5V Single-Supply Operation
♦ 2MHz Charge Pump Prevents AM Radio
Interference
®
DirectDrive architecture to produce a ground-refer-
♦ Ground-Referenced Outputs Eliminate Bulky DC-
enced output from a single supply, eliminating the need
for large DC-blocking capacitors, saving board space
and component height. The gain of the amplifier is set
internally (-1.5V/V) on the MAX13330 or adjusted exter-
nally with resistors on the MAX13331.
Blocking Capacitors
♦ Short-to-Ground and Battery (V
up to +45V)
BAT
Output Protection, Load Dump Protection
♦ Short-Circuit Diagnostic Output
The MAX13330/MAX13331 deliver 120mW per channel
into a 16Ω load or 135mW into a 32Ω load and have a
low 0.01% THD+N. Low output impedance and the effi-
cient integrated charge pump allows the device to drive
loads as low as 8Ω, enabling the use of small loud-
speakers. An 80dB at 217Hz PSRR allows these
devices to operate from noisy digital supplies without
an additional linear regulator. These devices include
15kV Human Body Model ESD protection and short-
circuit protection up to +45V at the headphone outputs.
Comprehensive click-and-pop circuitry suppresses
audible clicks and pops on startup and shutdown. A
low-power shutdown mode reduces the supply current
to 3µA (typ).
♦ Adjustable Gain (MAX13331) or Fixed -1.5V/V Gain
(MAX13330)
♦ 125mW per Channel into 32Ω at 0.01% THD+N
♦ Integrated Click-and-Pop Suppression
♦ High PSRR Eliminates LDO
♦ No Degradation of Low-Frequency Response Due
to Output Capacitors
♦
15kV Human Body Model ESD Protection for
Output Pins
Ordering Information
The MAX13330/MAX13331 are specified from -40°C to
+105°C AEC-Q100 Level 2 automotive temperature
range and are available in a 16-pin QSOP package.
TEMP
RANGE
PIN-
PACKAGE
PART
GAIN
MAX13330GEE/V+T -1.5V/V -40°C to +105°C 16 QSOP
Applications
Automotive Entertainment Systems
Externally
MAX13331GEE/V+T
-40°C to +105°C 16 QSOP
Set
/V denotes an automotive qualified part.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Automotive Rear Seat Entertainment Systems
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
Typical Application Circuits appear at end of data sheet.
Simplified Block Diagram
Pin Configuration
+
INL
SGND
INR
OUTL
PGND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
MAX13330
LEFT-CHANNEL
AUDIO IN
V
SS
SGND
OUTR
DIAG
MAX13330
MAX13331
CLICK-AND-POP
SUPPRESSION
DIAGNOSTICS
OUTPUT
SHDN
V
DD
SHDN
CPVDD
C1P
CPVSS
C1N
RIGHT-CHANNEL
AUDIO IN
PGND
QSOP
________________________________________________________________ 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.
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
ABSOLUTE MAXIMUM RATINGS
V
V
V
V
, CPVDD to SGND..............................................-0.3V to +6V
C1N to PGND..............................................(V - 0.3V) to +0.3V
SS
Output Short-Circuit Duration.....................................Continuous
DD
, CPVSS to SGND...............................................+0.3V to -6V
SS
, CPVDD..........................................................-0.3V to +0.3V
DD
Continuous Power Dissipation (T = +70°C)
A
, CPVSS ...........................................................-0.3V to +0.3V
SS
QSOP (derate 9.6mW/°C above +70°C))..................771.5mW
Operating Temperature Range .........................-40°C to +105°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
SHDN, DIAG to SGND................................-0.3V to (V
+ 0.3V)
DD
OUT_ to PGND.......................................(V
- 0.3V) to +45V
CPVSS
IN_ to SGND (MAX13330)................(V - 0.3V) to (V
+ 0.3V)
+ 0.3V)
+ 0.3V)
SS
DD
DD
IN_ to SGND (MAX13331)..........................-0.3V to (V
C1P to PGND........................................-0.3V to (V
CPVDD
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.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
QSOP
Junction-to-Ambient Thermal Resistance (θ ) ......103.7°C/W
JA
Junction-to-Case Thermal Resistance (θ )................37°C/W
JC
Note 1: 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.
0/MAX31
ELECTRICAL CHARACTERISTICS
(V
= V
= +5V, V
= V
= 0V, SHDN = V , C1 = C2 = 1µF, R = ∞, resistive load referenced to ground, for
DD
CPVDD
SGND
PGND DD L
MAX13330 gain = -1.5V/V (internally set), for MAX13331 gain = -1.5V/V (R = 30kΩ, R = 45kΩ), T = T = -40°C to +105°C, unless
otherwise noted. Typical values are at T = +25°C, unless otherwise noted.) (Note 2)
IN
FB
A
J
A
PARAMETER
GENERAL
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Amplifier Supply Voltage Range
V
4.0
4.0
5.5
5.5
V
V
DD
Charge-Pump Supply Voltage
Range
V
CPVDD
Charge-Pump Output Voltage
Quiescent Supply Current
Shutdown Supply Current
SHDN Input-Logic High
SHDN Input-Logic Low
SHDN Input Leakage Current
SHDN to Full Operation Time
DIAGNOSTICS
V
-V
V
mA
μA
V
CPVSS
DD
I
R = ꢀ
L
10
DD
SHDN
I
10
V
2
IH
V
0.8
+1
V
IL
-1
μA
μs
t
100
SON
0.02 x
No fault
V
DD
OUTR short to
SGND
0.22 x 0.25 x 0.28 x
V
DD
V
DD
V
DD
R
= ꢀ,
= +25°C
OUTL short to
SGND
0.47 x 0.50 x 0.53 x
DIAG
Diagnostic Output Voltage
V
DIAG
V
T
A
V
DD
V
DD
V
DD
OUTR short to
0.72 x 0.75 x 0.78 x
V
BAT
V
DD
V
DD
V
DD
OUTL short to
0.97 x
V
BAT
V
DD
2
_______________________________________________________________________________________
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
0/MAX31
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= +5V, V
= V
= 0V, SHDN = V , C1 = C2 = 1µF, R = ∞, resistive load referenced to ground, for
DD
CPVDD
SGND
PGND DD L
MAX13330 gain = -1.5V/V (internally set), for MAX13331 gain = -1.5V/V (R = 30kΩ, R = 45kΩ), T = T = -40°C to +105°C, unless
otherwise noted. Typical values are at T = +25°C, unless otherwise noted.) (Note 2)
IN
FB
A
J
A
PARAMETER
SYMBOL
CONDITIONS
MIN
130
130
TYP
MAX
UNITS
mA
Short-to-SGND Threshold
Short-to-V
Threshold
mA
BAT
AMPLIFIERS
Voltage Gain
A
MAX13330
MAX13330
-1.48
-1.5
0.2
1
-1.52
6
V/V
%
V
Gain Matching
Input Offset Voltage
Input Bias Current
Input Impedance
mV
nA
kꢁ
V
= 0V
50
IN_
R
MAX13330
DC, V = 4.0V to 5.5V, input referred
20
30
IN
-86
-80
75
DD
Power-Supply Rejection Ratio
PSRR
dB
f =1kHz, V
= 100mV
P-P
RIPPLE
R = 8ꢁ
L
THD+N = 1%;
= V = 5V;
CPVDD
Output Power Per Channel
P
V
DD
mW
R = 16ꢁ
L
120
135
2
OUT_
f
= 1kHz
IN
R = 32ꢁ
L
Output Voltage
V
R = 1kꢁ
L
V
OUT_
RMS
kꢁ
%
Output Impedance in Shutdown
14
R = 16ꢁ, P
L
= 100mW, f = 1kHz
= 125mW, f = 1kHz
0.03
0.01
100
Total Harmonic Distortion Plus
Noise
OUT
OUT
THD+N
SNR
R = 32ꢁ, P
L
%
Signal-to-Noise Ratio
R = 32ꢁ, P
L
= 135mW, f = 22Hz to 22kHz
OUT
dB
f = 22Hz to 22kHz bandwidth; inputs
AC-coupled to grounded
Noise
V
n
6
μV
RMS
Slew Rate
SR
0.3
V/μs
Maximum Capacitive Load
C
No sustained oscillation
3000
pF
dB
L
Peak voltage, T
=
A
Into shutdown
-80
-60
+25°C, A-weighted,
32 samples per
second; Inputs AC-
coupled to ground
Click-and-Pop Level
K
CP
Out of shutdown
Charge-Pump Oscillator
Frequency
f
1.9
2.2
-75
2.5
MHz
OSC
Crosstalk
R = 32ꢁ, V = 200mV , f = 10kHz
dB
°C
°C
kV
L
IN
P-P
Thermal-Shutdown Temperature
Thermal-Shutdown Hysteresis
ESD Protection
+155
10
Human Body Model (OUTR and OUTL)
15
Note 2: All devices are 100% tested at T = +25°C; specifications over temperature limits are guaranteed by design and QA
A
sampling.
_______________________________________________________________________________________
3
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
Typical Operating Characteristics
(V = V
= 5V, V
= V
= 0V, C1 = C2 = 1µF, R = ∞, gain = -1.5V/V, THD+N measurement bandwidth = 22Hz to 22kHz,
DD
CPVDD
SGND
PGND L
T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
1
1
0.1
1
0.1
V
= 4V
V
= 5V
V
= 4V
DD
DD
L
DD
R = 8Ω
R = 8Ω
L
R = 16Ω
L
P
= 25mW
P
= 25mW
0.1
0.01
OUT
OUT
P
OUT
= 25mW
P
= 45mW
P
= 60mW
OUT
OUT
0.01
0.001
0.01
0.001
P
= 75mW
OUT
0.001
0.01
0.01
0
0.1
1
FREQUENCY (kHz)
10
100
100
75
0.01
0.01
0
0.1
1
FREQUENCY (kHz)
10
100
100
125
0.01
0.01
0
0.1
1
10
100
100
125
FREQUENCY (kHz)
0/MAX31
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
1
0.1
1
0.1
1
0.1
V
= 5V
R = 32Ω
V
= 5V
R = 16Ω
V
L
= 4V
R = 32Ω
DD
L
DD
L
DD
P
= 50mW
OUT
P
= 25mW
OUT
P
= 50mW
OUT
0.01
0.001
0.01
0.001
0.01
0.001
P
= 100mW
OUT
P
= 70mW
10
OUT
P
= 125mW
10
OUT
0.1
1
0.1
1
10
0.1
1
FREQUENCY (kHz)
FREQUENCY (kHz)
FREQUENCY (kHz)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
10
1
10
1
10
1
V
= 4V
V
DD
= 5V
V
= 4V
DD
R = 16Ω
DD
L
R = 8Ω
R = 8Ω
L
L
f
IN
= 10kHz
f
= 10kHz
= 100Hz
IN
f = 1kHz
IN
f
IN
= 10kHz
f
IN
= 1kHz
f
IN
= 1kHz
0.1
0.1
0.01
0.1
0.01
0.01
0.001
f
= 100Hz
f
IN
IN
f
IN
= 100Hz
25
50
25
50
75
100
25
50
75
100
OUTPUT POWER (mW)
OUTPUT POWER (mW)
OUTPUT POWER (mW)
4
_______________________________________________________________________________________
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
0/MAX31
Typical Operating Characteristics (continued)
(V = V
= 5V, V
= V
= 0V, C1 = C2 = 1µF, R = ∞, gain = -1.5V/V, THD+N measurement bandwidth = 22Hz to 22kHz,
DD
CPVDD
SGND
PGND L
T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
10
10
1
10
1
V
= 5V
V
= 4V
V
= 5V
DD
R = 32Ω
L
DD
DD
R = 16Ω
R = 32Ω
L
L
1
0.1
f
IN
= 10kHz
f
IN
= 10kHz
f
IN
= 10kHz
f
= 1kHz
IN
f
IN
= 1kHz
f
IN
= 1kHz
0.1
0.1
0.01
0.001
0.01
0.001
0.01
0.001
f
IN
= 100Hz
f
IN
= 100Hz
50
f
= 100Hz
50
IN
0
25
50
75 100 125 150 175
0
25
75
100
125
0
25
75 100 125 150 175
OUTPUT POWER (mW)
OUTPUT POWER (mW)
OUTPUT POWER (mW)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
OUTPUT POWER vs. SUPPLY VOLTAGE
OUTPUT POWER vs. LOAD RESISTANCE
180
160
140
120
100
80
200
180
160
140
120
100
80
1
f
IN
= 1kHz
f = 1kHz
IN
V
= 5V
10% THD+N
= 5V
DD
1% THD+N
R = 1kΩ
V
L
DD
V
= 2V
RMS
OUT_
0.1
0.01
1% THD+N
= 5V
10% THD+N
= 4V
V
R = 32Ω
L
DD
V
DD
V
= 1V
RMS
OUT_
R = 16Ω
L
60
60
R = 8Ω
L
0.001
40
40
1% THD+N
= 4V
V
20
DD
20
0
0
0.0001
4.00 4.25 4.50 4.75 5.00 5.25 5.50
SUPPLY VOLTAGE (V)
0
10
100
1000
0.01
0.1
1
10
100
LOAD RESISTANCE (Ω)
FREQUENCY (kHz)
POWER DISSIPATION vs.
OUTPUT POWER PER CHANNEL
POWER DISSIPATION vs.
OUTPUT POWER PER CHANNEL
800
700
600
500
400
300
200
100
1200
1000
800
600
400
200
0
V
= 4V
V
DD
= 5V
DD
f
= 1kHz
f = 1kHz
IN
IN
R = 8Ω
R = 16Ω
L
R = 8Ω
L
L
R = 16Ω
L
R = 32Ω
L
R = 32Ω
L
0
0
20
40
60
80
100
120
0
20 40 60 80 100 120 140 160 180
OUTPUT POWER PER CHANNEL (mW)
OUTPUT POWER PER CHANNEL (mW)
_______________________________________________________________________________________
5
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
Typical Operating Characteristics (continued)
(V = V
= 5V, V
= V
= 0V, C1 = C2 = 1µF, R = ∞, gain = -1.5V/V, THD+N measurement bandwidth = 22Hz to 22kHz,
DD
CPVDD
SGND
PGND L
T
A
= +25°C, unless otherwise noted.)
POWER-SUPPLY REJECTION RATIO
GAIN FLATNESS vs. FREQUENCY
CROSSTALK vs. FREQUENCY
vs. FREQUENCY
3.5
3.4
3.3
-40
-50
-40
V
= 200mV
P-P
IN
-50
R = 32Ω
L
V
= 4V
-60
-70
DD
OUTR
OUTR
OUTL
-60
V
OUTL
= 4V
DD
-70
RIGHT TO LEFT
-80
3.2
3.1
3.0
-90
V
= 5V
DD
-80
OUTR
V = 100mV
RIPPLE
-100
-110
-120
MAX13330
-90
LEFT TO RIGHT
0.1
V
OUTL
= 5V
DD
P-P
V
= 100mV
IN
P-P
R = 32Ω
L
-100
0.01
0.1
1
10
100
1000
0.01
1
10
100
0.01
0.1
1
10
100
FREQUENCY (kHz)
FREQUENCY (kHz)
FREQUENCY (kHz)
0/MAX31
OUTPUT FFT
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
0
-20
10
9
12
10
8
R = 32Ω
L
8
-40
7
6
-60
5
6
-80
4
3
2
1
0
4
-100
-120
-140
2
0
0
5
10
15
20
4.00
4.25 4.50 4.75 5.00 5.25 5.50
SUPPLY VOLTAGE (V)
-50 -25
0
25
50
75 100 125
FREQUENCY (kHz)
TEMPERATURE (°C)
SHUTDOWN CURRENT vs. TEMPERATURE
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
EXITING SHUTDOWN TRANSIENT
MAX13330/31 toc26
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
5
V
SHDN
4
3
2
1
0
5V/div
V
OUTL
1V/div
V
OUTR
1V/div
-50 -25
0
25
50
75 100 125
4.00 4.25 4.50 4.75
5.00 5.25 5.50
200μs/div
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
6
_______________________________________________________________________________________
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
0/MAX31
Typical Operating Characteristics (continued)
(V = V
= 5V, V
= V
= 0V, C1 = C2 = 1µF, R = ∞, gain = -1.5V/V, THD+N measurement bandwidth = 22Hz to 22kHz,
DD
CPVDD
SGND
PGND L
T
A
= +25°C, unless otherwise noted.)
ENTERING SHUTDOWN TRANSIENT
POWER-UP/-DOWN TRANSIENT
MAX13330/31 toc28
MAX13330/31 toc27
V
V
SHDN
SHDN
5V/div
5V/div
V
V
OUTL
OUTL
1V/div
1V/div
V
V
OUTR
OUTR
1V/div
1V/div
200μs/div
10ms/div
Pin Description
PIN
NAME
FUNCTION
1
INL
Inverting Left-Channel Audio Input
Amplifier Signal Ground. The noninverting inputs of the amplifiers are connected to the amplifier
signal ground. Connect both to the signal ground plane.
2, 4
3
SGND
INR
Inverting Right-Channel Audio Input
Amplifier Positive-Power Supply. Connect to positive supply. Bypass with a 1µF capacitor to
SGND as close to the pin as possible.
5
V
DD
6
SHDN
Active-Low Shutdown Input
Charge-Pump Power Supply. Powers charge-pump inverter, charge-pump logic, and oscillator.
Connect to positive supply. Bypass with a 1µF capacitor to PGND as close to the pin as possible.
7
CPVDD
8
9, 15
10
C1P
PGND
C1N
Flying-Capacitor Positive Terminal. Connect a 1µF capacitor between C1P and C1N.
Power Ground. Connect both to the power ground plane.
Flying-Capacitor Negative Terminal. Connect a 1µF capacitor between C1P and C1N.
11
CPVSS
DIAG
OUTR
Charge-Pump Output. Connect to V and bypass with a 1µF capacitor to PGND.
SS
12
Diagnostic Voltage Output
13
Right-Channel Output
14
V
Amplifier Negative Power Supply. Connect to CPVSS.
Left-Channel Output
SS
16
OUTL
_______________________________________________________________________________________
7
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
Detailed Description
The MAX13330/MAX13331 headphone amplifiers fea-
ture Maxim’s DirectDrive architecture, eliminating the
large output-coupling capacitors required by conven-
tional single-supply headphone amplifiers. The devices
consists of two Class AB headphone amplifiers, under-
voltage lockout (UVLO), low-power shutdown control,
comprehensive click-and-pop suppression, output
short-circuit/ESD protection and output short-circuit
diagnostics.
V
V
DD
V
OUT
/2
DD
GND
These devices can drive loads as low as 8Ω, and deliv-
er up to 120mW per channel into 16Ω and 135mW into
32Ω. The MAX13330 features a fixed gain of -1.5V/V,
and the MAX13331 features a programmable gain con-
figured with external resistors. The headphone outputs
feature 15kV Human Body Model ESD protection, and
enhanced short-circuit protection to ground or battery
CONVENTIONAL DRIVER-BIASING SCHEME
(V
up to +45V). An integrated short-circuit diagnos-
BAT
tic output provides the status of the MAX13330/
MAX13331 during operation as a fraction of the analog
supply voltage.
V
DD
0/MAX31
DirectDrive
Conventional single-supply headphone amplifiers have
their outputs biased about a nominal DC voltage (typi-
cally half the supply) for maximum dynamic range.
Large coupling capacitors are needed to block this DC
bias from the headphone. Without these capacitors, a
significant amount of DC current flows to the head-
phone, resulting in unnecessary power dissipation and
possible damage to both the headphone and the head-
phone amplifier.
V
OUT
GND
V
SS
DirectDrive BIASING SCHEME
Maxim’s DirectDrive architecture uses a charge pump
to create an internal negative-supply voltage, allowing
the MAX13330/MAX13331 outputs to be biased about
SGND (Figure 1). With no DC component, there is no
need for the large DC-blocking capacitors. Instead of
two large (220µF, typ) tantalum capacitors, the
MAX13330/MAX13331 charge pump requires two small
ceramic capacitors, conserving board space, reducing
cost, and improving the frequency response of the
headphone amplifier. See the Output Power vs. Load
Resistance graph in the Typical Operating
Characteristics for details of the possible capacitor
sizes. There is a low DC voltage on the amplifier out-
puts due to amplifier offset. However, the output offset
of the MAX13330 is typically 2.5mV which, when com-
bined with a 32Ω load, results in less than 78µA of DC
current flow to the headphones. Previous attempts to
eliminate the output-coupling capacitors involved bias-
ing the headphone return (sleeve) to the DC-bias volt-
age of the headphone amplifiers.
Figure 1. Conventional Driver Output Waveform vs. MAX13330/
MAX13331 Output Waveform
This method raises some issues:
•
The sleeve is typically grounded to the chassis.
Using this biasing approach, the sleeve must be
isolated from system ground, complicating product
design.
•
•
During an ESD strike, the amplifier’s ESD structures
are the only path to system ground. Thus, the ampli-
fier must be able to withstand the full ESD strike.
When using the headphone jack as a line out to
other equipment, the bias voltage on the sleeve
may conflict with the ground potential from other
equipment, resulting in possible damage to the
amplifiers.
8
_______________________________________________________________________________________
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
0/MAX31
Low-Frequency Response
In addition to the cost and size disadvantages of the DC-
blocking capacitors required by conventional head-
phone amplifiers, these capacitors limit the amplifier’s
low-frequency response and can distort the audio signal:
2) The voltage coefficient of the DC-blocking capacitor
contributes distortion to the reproduced audio signal as
the capacitance value varies and the function of the
voltage across the capacitor changes. The reactance
of the capacitor dominates at frequencies below the
-3dB point and the voltage coefficient appears as fre-
quency-dependent distortion. Figure 3 shows the
THD+N introduced by two different capacitor dielectric
types. Note that below 100Hz, THD+N increases rapid-
ly. The combination of low-frequency attenuation and
frequency-dependent distortion compromises audio
reproduction in portable audio equipment that empha-
sizes low-frequency effects such as in multimedia lap-
tops, MP3, CD, and DVD players. By eliminating the
DC-blocking capacitors through DirectDrive technolo-
gy, these capacitor-related deficiencies are eliminated.
1) The impedance of the headphone load and the DC-
blocking capacitor form a highpass filter with the -3dB
point set by:
1
f
=
Hz
(
)
−3dB
2π ×R × C
L
OUT
where R is the impedance of the headphone and
L
C
is the value of the DC-blocking capacitor. The
OUT
highpass filter is required by conventional single-
ended, single power-supply headphone amplifiers to
block the midrail DC-bias component of the audio sig-
nal from the headphones. The drawback to the filter is
that it can attenuate low-frequency signals. Larger val-
ADDITIONAL THD+N DUE
TO DC-BLOCKING CAPACITORS
10
ues of C
reduce this effect but result in physically
OUT
larger, more expensive capacitors. Figure 2 shows the
relationship between the size of C and the resulting
1
OUT
low-frequency attenuation. Note that the -3dB point for
a 16Ω headphone with a 100µF blocking capacitor is
100Hz, well within the normal audio band, resulting in
low-frequency attenuation of the reproduced signal.
0.1
TANTALUM
0.01
LOW-FREQUENCY ROLLOFF
0.001
(R = 16Ω)
L
ALUM/ELEC
0
0.0001
-3
10
100
1k
10k
100k
DirectDrive
330μF
220μF
100μF
-6
-9
FREQUENCY (Hz)
-12
Figure 3. Distortion Contributed by DC-Blocking Capacitors
-15
-18
Charge Pump
The MAX13330/MAX13331 feature a low-noise charge
pump. The 2.2MHz (typ) switching frequency is well
beyond the audio range. It does not interfere with the
audio signals and avoids AM band interference. The
switch drivers feature a controlled switching speed that
minimizes noise generated by turn-on and turn-off tran-
sients. By limiting the switching speed of the charge
pump, the di/dt noise caused by the parasitic bond
wire and trace inductance is minimized. Although not
typically required, additional high-frequency noise
attenuation can be achieved by increasing the value of
C2 (see the Typical Application Circuits).
33μF
-21
-24
-27
-30
10
100
1k
FREQUENCY (Hz)
10k
100k
Figure 2. Low-Frequency Attenuation for Common DC-Blocking
Capacitor Values
_______________________________________________________________________________________
9
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
Additionally, the MAX13330/MAX13331 feature exten-
sive click-and-pop suppression that eliminates any
audible transient sources internal to the device. The
Power-Up/-Down Transient graph in the Typical
Operating Characteristics shows that there is minimal
DC shift and no spurious transients at the output upon
startup or shutdown.
Diagnostic Output
The MAX13330/MAX13331 provides an analog diag-
nostic output as a fraction of the analog supply voltage
V
. The voltage at DIAG will correspond to the fault
DD
condition with the highest priority that is present in the
system, as shown in Table 1. When simultaneous fault
conditions occur on both headphone outputs, the diag-
nostic output will only report the fault condition at OUTR
until it is cleared or removed. Only then will the fault
condition at OUTL be reported at DIAG. Connect DIAG
to a high-impedance input.
In most applications, the output of the preamplifier dri-
ving the MAX13330/MAX13331 has a DC bias of typi-
cally half the supply. At startup, the input-coupling
capacitor is charged to the preamplifier’s DC-bias volt-
age through the feedback resistor of the MAX13330/
MAX13331, resulting in a DC shift across the capacitor
and an audible click/pop. Delaying the rise of SHDN 4
Table 1. MAX13330/MAX13331 Diagnostic
Priority
to 5 time constants (80ms to 100ms) based on R and
IN
C
relative to the startup of the preamplifier, eliminates
IN
V
STATE
PRIORITY
DIAG
this click/pop caused by the input filter.
V
OUTL Short to V
3
1
DD
BAT
3/4 V
1/2 V
1/4 V
0
OUTR Short to V
BAT
Shutdown
DD
DD
DD
The MAX13330/MAX13331 feature shutdown control
allowing audio signals to be shut down or muted.
OUTL Short to SGND
OUTR Short to SGND
No Fault
4
2
0/MAX31
Driving SHDN low disables the amplifiers and the
charge pump, sets the amplifier output impedance to
14kΩ (typ), and reduces the supply current. In shut-
down mode, the supply current is reduced to 2µA. The
charge pump is enabled once SHDN is driven high.
5
Three State
Shutdown
—
For both headphone outputs, short circuits to V
are
BAT
dynamic and V
will be automatically cleared as
DIAG
Applications Information
soon as the fault condition is removed. Short circuits to
GND occurring when a positive output voltage is pre-
Power Dissipation
Under normal operating conditions, linear power ampli-
fiers can dissipate a significant amount of power. The
maximum power dissipation for each package is given
in the Absolute Maximum Ratings section under contin-
uous power dissipation or can be calculated by the
following equation:
sent on OUTL or OUTR, will result in V
latched until the fault condition is cleared.
being
DIAG
When V
is latched, it can be cleared by either tog-
DIAG
gling SHDN low for less than 5µs or initiating a full reset
of the MAX13330/MAX13331. Toggling SHDN low for
less than 5µs will cause the fault to ground to be
cleared without shutting down the device or interrupting
the output state of the amplifiers. A full reset requires
SHDN to be pulled low for more than 50µs. The amplifi-
er outputs will enter high impedance and remain in that
state until the device exits shutdown.
(T
− T )
A
J(MAX)
P
=
DISSPKG(MAX)
θ
JA
where T
is +145°C, T is the ambient tempera-
A
J(MAX)
Click-and-Pop Suppression
In conventional single-supply audio amplifiers, the out-
put-coupling capacitor is a major contributor of audible
clicks and pops. Upon startup, the amplifier charges
the coupling capacitor to its bias voltage, typically half
the supply. Likewise, on shutdown, the capacitor is dis-
charged to SGND. This results in a DC shift across the
capacitor which appears as an audible transient at the
speaker. Since the MAX13330/MAX13331 does not
require output-coupling capacitors, this problem does
not arise.
ture, and θ is the reciprocal of the derating factor in
JA
°C/W as specified in the Absolute Maximum Ratings
section. The thermal resistance θ of the QSOP pack-
JA
age is 120°C/W.
The MAX13330/MAX13331 have two power dissipation
sources: the charge pump and two amplifiers. If power
dissipation for a given application exceeds the maxi-
mum allowed for a particular package, either reduce
V
DD
, increase load impedance, decrease the ambient
temperature, or add heatsinking to the device. Large
output, supply, and ground traces improve the maxi-
mum power dissipation in the package.
10 ______________________________________________________________________________________
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
0/MAX31
Thermal-overload protection limits total power dissipa-
tion in the MAX13330/MAX13331. When the junction
Component Selection
Gain-Setting Resistors (MAX13331 Only)
The gain of the MAX13330 is internally set at -1.5V/V.
All gain-setting resistors are integrated into the device,
reducing external component count. The internally set
gain, in combination with DirectDrive, results in a head-
phone amplifier that requires only five tiny 1µF capaci-
tors to complete the amplifier circuit: two for the
charge-pump, two for audio input coupling, and one for
power-supply bypassing (see the Typical Application
Circuits). The gain of the MAX13331 amplifier is set
externally as shown in the Typical Application Circuits,
the gain is:
temperature exceeds +145°C (typ), the thermal-protec-
tion circuitry disables the amplifier output stage. The
amplifiers are enabled once the junction temperature
cools by 5°C. This results in a pulsing output under
continuous thermal-overload conditions.
Output Power
The device has been specified for the worst-case sce-
nario, when both inputs are in-phase. Under this condi-
tion, the amplifiers simultaneously draw current from the
charge pump, leading to a proportional reduction in
V
SS
headroom. 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 4 shows
the two extreme cases for in- and out-of-phase. In reali-
ty, the available power lies between these extremes.
R
F
A
= −
(V/V)
V
R
IN
Choose feedback resistor values of 10kΩ. Values other
than 10kΩ increase output offset voltage due to the
input bias current, which in turn, increases the amount
of DC current flow to the load.
OUTPUT POWER vs. SUPPLY VOLTAGE
250
f
= 1kHz
IN
L
INPUTS 180°
OUT OF PHASE
R = 32Ω
THD+N = 10%
Input Filtering
The input capacitor (C ), in conjunction with the input
IN
200
150
100
50
resistor (R ), forms a highpass filter that removes the
IN
DC bias from an incoming signal (see the Typical
Application Circuits). The AC-coupling capacitor allows
the device to bias the signal to an optimum DC level.
Assuming zero source impedance, the -3dB point of
the highpass filter is given by:
INPUTS
IN PHASE
1
f
=
(Hz)
−3dB
2π ×R × C
IN
IN
0
4.00 4.25 4.50 4.75 5.00 5.25
SUPPLY VOLTAGE (V)
5.50
Choose C so f
is well below the lowest frequency
IN
-3dB
of interest. For the MAX13330, use the value of R as
IN
given in the Electrical Characteristics table. Setting
Figure 4. Output Power vs. Supply Voltage
f
too high affects the device’s low-frequency
-3dB
response. Use capacitors whose dielectrics have low-
voltage coefficients, such as tantalum or aluminum
electrolytic. Capacitors with high-voltage coefficients,
such as ceramics, can result in increased distortion at
low frequencies.
UVLO
The MAX13330/MAX13331 feature a UVLO function that
prevents the device from operating if the supply voltage
is less than 3.6V (typ). This feature ensures proper
operation during brownout conditions and prevents
deep battery discharge. Once the supply voltage
reaches the UVLO threshold, the charge-pump is
turned on and the amplifiers are powered.
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.
______________________________________________________________________________________ 11
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
Flying Capacitor (C1)
The value of the flying capacitor (C1) affects the charge
pump’s load regulation and output resistance. 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. Increasing the value of C1 improves
load regulation and reduces the charge-pump output
resistance to an extent. See the Output Power vs.
Load Resistance graph in the Typical Operating
Characteristics. Above 1µF, the on-resistance of the
switches and the ESR of C1 and C2 dominate.
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Connect CPVDD and V
together at the
DD
device. Connect CPVSS and V
together at the
SS
device. Bypassing of both supplies is accomplished by
charge-pump capacitors C2 and C3 (see the Typical
Application Circuits). Place capacitors C2 and C3 as
close to the device as possible and bypass them to the
PGND plane. Keep PGND and all traces that carry
switching transients as short as possible to minimize
EMI. Route them away from SGND, the audio signal
path, and the external feedback components
(MAX13331). Connect the PGND plane and the SGND
plane together at a single point on the PCB. Refer to
the MAX13330/MAX13331 Evaluation Kit for layout
guidelines.
Holding Capacitor (C2)
The hold capacitor value and ESR directly affect the
ripple at CPVSS. Increasing the value of C2 reduces
output ripple. Likewise, decreasing the ESR of C2
reduces both ripple and output resistance. Lower
capacitance values can be used in systems with low
maximum output power levels. See the Output Power
vs. Load Resistance graph in the Typical Operating
Characteristics.
ESD Protection
To pass module level ESD requirements, it may be nec-
essary to add ESD diodes to the MAX13330/MAX13331
outputs. Connect the anode to the CPVSS supply, and
connect the cathode to an output pin, as shown in the
Typical Application Circuits.
0/MAX31
Power-Supply Bypass Capacitor (C3)
The power-supply bypass capacitor (C3) lowers the
output impedance of the power supply and reduces the
impact of the MAX13330/MAX13331 charge-pump
switching transients. Bypass CPVDD with C3, the same
value as C1, and place it physically close to the CPVDD
and PGND pins.
12 ______________________________________________________________________________________
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
0/MAX31
Typical Application Circuits
4V to 5.5V
0.33μF
C3
LEFT CHANNEL
AUDIO IN
1μF
V
DD
INL
CPVDD
SHDN
45kΩ
V
DD
30kΩ
UVLO/
SHUTDOWN
CONTROL
OUTL
DIAG
OUTR
1nF
C1P
C1N
V
SS
C1
1μF
CHARGE
PUMP
CLICK-AND-POP
SUPPRESSION
10nF
V
SS
30kΩ
MAX13330
V
DD
1nF
45kΩ
ESD PROTECTION
DIODES
V
CPVSS
PGND
SGND
INR
SS
RIGHT CHANNEL
AUDIO IN
C2
1μF
CPVSS
0.33μF
______________________________________________________________________________________ 13
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
Typical Application Circuits (continued)
C
IN
R
IN
0.33μF
30kΩ
LEFT CHANNEL
AUDIO IN
4V to 5.5V
R
F
C3
1μF
45kΩ
V
INL
CPVDD
SHDN
DD
V
DD
UVLO/
SHUTDOWN
CONTROL
OUTL
DIAG
OUTR
1nF
C1P
C1N
V
SS
C1
1μF
CHARGE
PUMP
CLICK-AND-POP
SUPPRESSION
0/MAX31
10nF
V
SS
MAX13331
V
DD
1nF
ESD PROTECTION
DIODES
V
CPVSS
PGND
SGND
INR
SS
C2
1μF
CPVSS
R
F
R
IN
45kΩ
30kΩ
RIGHT CHANNEL
AUDIO IN
C
IN
0.33μF
Package Information
For the latest package outline information and land patterns (footprints), 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.
21-0055
LAND PATTERN NO.
90-0167
16 QSOP
E16+4
14 ______________________________________________________________________________________
Automotive DirectDrive Headphone Amplifiers
with Output Protection and Diagnostics
0/MAX31
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
10/08
4/09
0
1
Initial release
—
Corrected the Features section for THD+N, style edits
1, 2, 3, 15
Updated the continuous power dissipation numbers in the Absolute Maximum Ratings
section; added the Package Thermal Characteristics section; added the ESD
Protection section; updated the Typical Application Circuits to add the ESD protection
diodes
2
1
5/11
7/11
2, 12, 13, 14
Corrected the units for the click-and-pop level parameter from V to dB in the Electrical
Characteristics table
3
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
© 2011 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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