General Description
The MAX9750/MAX9751/MAX9755 combine a stereo,
2.6W audio power amplifier and stereo DirectDrive®
110mW headphone amplifier in a single device. The
headphone amplifier uses Maxim’s DirectDrive architec-
ture that produces a ground-referenced output from a
single supply, eliminating the need for large DC-blocking
capacitors, saving cost, space, and component height.
A high 90dB PSRR and low 0.01% THD+N ensures
clean, low-distortion amplification of the audio signal.
The MAX9750 features an analog volume control, and a
BEEP input. The MAX9751 features a 2:1 input multiplexer,
allowing multiple audio sources to be selected. All devices
feature a single-supply voltage, a shutdown mode, logic-
selectable gain, and a headphone sense input. Industry-
leading click-and-pop suppression eliminates audible
transients during power and shutdown cycles.
The MAX9750/MAX9751/MAX9755 are offered in a
space-saving, thermally efficient 28-pin thin QFN (5mm
x 5mm x 0.8mm) package. These devices have thermal-
overload and output short-circuit protection, and are
specified over the extended -40°C to +85°C tempera-
ture range.
Applications
Notebook PCs Flat-Panel TVs
Tablet PCs PC Displays
Portable DVD Players LCD Projectors
Features
♦No DC-Blocking Capacitors Required—Provides
Industry’s Most Compact Notebook Audio
Solution
♦PC2001 Compliant
♦5V Single-Supply Operation
♦Class AB 2.6W Stereo BTL Speaker Amplifiers
♦110mW DirectDrive Headphone Amplifiers
♦High 90dB PSRR
♦Low-Power Shutdown Mode
♦Industry-Leading Click-and-Pop Suppression
♦Low 0.01% THD+N at 1kHz
♦Short-Circuit and Thermal Protection
♦Selectable Gain Settings
♦Analog Volume Control (MAX9750)
♦BEEP Input with Glitch Filter (MAX9750)
♦2:1 Stereo Input MUX (MAX9751)
♦±8kV ESD-Protected Headphone Driver Outputs
♦Available in Space-Saving, Thermally Efficient
28-Pin Thin QFN (5mm x 5mm x 0.8mm) Package
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-3006; Rev 8; 6/08
EVALUATION KIT
AVAILABLE
PART* PIN-
PACKAGE
M A XIM U M GA IN
( d B )
MAX9750AETI+28 Thi n QFN 13.5
MAX9750BETI+28 Thi n QFN 19.5
MAX9750CETI+28 Thi n QFN 10.5
MAX9751ETI+28 Thi n QFN 10.5
MAX9755ETI+28 Thi n QFN 10.5
+
Denotes a lead-free/RoHS-compliant package.
*
All devices specified over the -40°C to +85°C temperature
range.
VOL
BEEP
MAX9750
Simplified Block Diagrams
Simplified Block Diagrams continued at end of data sheet.
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.
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
Supply Voltage (VDD, PVDD, HPVDD, CPVDD to GND)..........+6V
GND to PGND.....................................................................±0.3V
CPVSS, C1N, VSS to GND .........................-6.0V to (GND + 0.3V)
HPOUT_ to GND ....................................................................±3V
Any Other Pin .............................................-0.3V to (VDD + 0.3V)
Duration of OUT_ Short Circuit to GND or PVDD........Continuous
Duration of OUT_+ Short Circuit to OUT_- .................Continuous
Duration of HPOUT_ Short Circuit to GND,
VSS or HPVDD.........................................................Continuous
Continuous Current (PVDD, OUT_, PGND) ...........................1.7A
Continuous Current (CPVDD, C1N, C1P, CPVSS, VSS, HPVDD,
HPOUT_) .......................................................................850mA
Continuous Input Current (All Other Pins) ........................±20mA
Continuous Power Dissipation (TA= +70°C, multilayer board)
28-Pin Thin QFN (derate 23.8mW/°C above +70°C) .1900mW
Junction-to-Case Thermal Resistance (θJC)
28-Pin Thin QFN...........................................................24°C/W
Junction Temperature......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(VDD = PVDD = CPVDD = HPVDD = 5V, VGND = VPGND = VCPGND = 0V, SHDN = VDD, CBIAS = 1µF, C1 = C2 = 1µF, speaker load
terminated between OUT_+ and OUT_-, headphone load terminated between HPOUT_ and GND, VGAIN1 = VGAIN2 = VVOL = VGAIN = 0V,
TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
GENERAL
Supply Voltage Range VDD, PVDD Inferred from PSRR test 4.5 5.5 V
Headphone Supply Voltage CPVDD,
HPVDD Inferred from PSRR test 3.0 5.5 V
HPS = GND, speaker mode, RL = ∞14 29
Quiescent Supply Current IDD HPS = VDD, headphone mode, RL = ∞713
mA
Shutdown Supply Current ISHDN SHDN = GND 0.2 5 µA
Bias Voltage VBIAS 1.7 1.8 1.9 V
Switching Time tSW Gain or input switching 10 µs
MAX9750 10 20 30
Input Resistance RIN Amplifier inputs
(Note 2) MAX9751/MAX9755 4.5 6 8.0 kΩ
Turn-On Time tSON 25 ms
SPEAKER AMPLIFIER (HPS = GND)
MAX9750A/MAX9750B/
MAX9751/MAX9755 ±1±15
Output Offset Voltage VOS
Measured
between OUT_+
and OUT_-,
TA = +25°C MAX9750C ±0.4 ±6
mV
MAX9750A/MAX9750B/
MAX9750C/MAX9751 75 90
PVDD or VDD =
4.5V to 5.5V
(TA = +25°C) MAX9755 72 90
f = 1kHz, VRIPPLE = 200mVP-P 80
Power-Supply Rejection Ratio
(Note 3) PSRR
f = 10kHz, VRIPPLE = 200mVP-P 55
dB
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD = PVDD = CPVDD = HPVDD = 5V, VGND = VPGND = VCPGND = 0V, SHDN = VDD, CBIAS = 1µF, C1 = C2 = 1µF, speaker load
terminated between OUT_+ and OUT_-, headphone load terminated between HPOUT_ and GND, VGAIN1 = VGAIN2 = VVOL = VGAIN = 0V,
TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX9750A/
MAX9750B/
MAX9751/
MAX9755
0.9 1.4
RL = 8Ω
MAX9750C 0.65 0.8
MAX9750A/
MAX9750B/
MAX9751/
MAX9755
2.3
RL = 4Ω
MAX9750C 1.2 1.5
MAX9750A/
MAX9750B/
MAX9751/
MAX9755
2.6
Output Power (Note 4) POUT
THD+N = 1%,
f = 1kHz,
TA = +25°C
RL = 3Ω
MAX9750C 2.2
W
RL = 8Ω, POUT = 500mW, f = 1kHz 0.01
Total Harmonic Distortion Plus
Noise THD+N RL = 4Ω, POUT = 1W, f = 1kHz 0.02 %
Signal-to-Noise Ratio SNR RL = 8Ω, POUT = 500mW, BW = 22Hz to
22kHz 96 dB
Noise VnBW = 22Hz to 22kHz, A-weighted 22 µVRMS
Capacitive-Load Drive CLNo sustained oscillations 200 pF
Crosstalk L to R, R to L, f = 10kHz 75
Off-Isolation Any unselected input to any active input,
f = 10kHz (MAX9751), input referred 75 dB
Slew Rate SR 1.4 V/µs
GAIN1 = 0, GAIN2 = 0 9
GAIN1 = 1, GAIN2 = 0 10.5
GAIN1 = 0, GAIN2 = 1 12
MAX9750A
GAIN1 = 1, GAIN2 = 1 13.5
GAIN1 = 0, GAIN2 = 0 15
GAIN1 = 1, GAIN2 = 0 16.5
GAIN1 = 0, GAIN2 = 1 18
MAX9750B
GAIN1 = 1, GAIN2 = 1 19.5
GAIN1 = 0, GAIN2 = 0 6
GAIN1 = 1, GAIN2 = 0 7.5
GAIN1 = 0, GAIN2 = 1 9
Gain (Maximum Volume Setting) AVMAX
(
SPKR
)
MAX9750C
GAIN1 = 1, GAIN2 = 1 10.5
dB
GAIN = 1 9
Gain (MAX9751/MAX9755) AVGAIN = 0 10.5 dB
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VDD = PVDD = CPVDD = HPVDD = 5V, VGND = VPGND = VCPGND = 0V, SHDN = VDD, CBIAS = 1µF, C1 = C2 = 1µF, speaker load
terminated between OUT_+ and OUT_-, headphone load terminated between HPOUT_ and GND, VGAIN1 = VGAIN2 = VVOL = VGAIN = 0V,
TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
HEADPHONE AMPLIFIER (HPS = VDD)
Output Offset Voltage VOS TA = +25°C ±2±7mV
HPVDD = 3V to 5.5V, TA = +25°C 60 75
f = 1kHz, VRIPPLE = 200mVP-P 73
Power-Supply Rejection Ratio
(Note 3) PSRR
f = 10kHz, VRIPPLE = 200mVP-P 63
dB
RL = 32Ω40 50
Output Power POUT THD+N = 1%,
f = 1kHz, TA = +25°C RL = 16Ω110
mW
RL = 32Ω, POUT = 20mW, f = 1kHz 0.007
Total Harmonic Distortion Plus
Noise THD+N RL = 16Ω, POUT = 75mW, f = 1kHz 0.03 %
Signal-to-Noise Ratio SNR RL = 32Ω, POUT = 50mW, BW = 22Hz to
22kHz 101 dB
Noise VnBW = 22Hz to 22kHz 11 µVRMS
Capacitive-Load Drive CLNo sustained oscillations 200 pF
Crosstalk L to R, R to L, f = 10kHz 88
Off-Isolation Any unselected input to any active input,
f = 10kHz (MAX9751), input referred 74 dB
Slew Rate SR 0.4 V/µs
ESD ESD IEC air discharge ±8 kV
GAIN2 = GAIN = 0, GAIN1 = X 3
Gain AVGAIN2 = GAIN = 1, GAIN1 = X 0 dB
CHARGE PUMP
Charge-Pump Frequency fOSC 500 550 600 kHz
VOLUME CONTROL (MAX9750_)
VOL Input Impedance RVOL 100 MΩ
VOL Input Hysteresis 10 mV
Full Mute Input Voltage (Note 5) 0.858 x
HPVDD V
Channel Matching AV = -25dB to +13.5dB ±0.2 dB
BEEP INPUT (MAX9750_)
Beep Signal Minimum Amplitude VBEEP RB = 33kΩ (Note 6) 0.8 VP-P
Beep Signal Minimum Frequency fBEEP 300 Hz
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(VDD = PVDD = CPVDD = HPVDD = 5V, VGND = VPGND = VCPGND = 0V, SHDN = VDD, CBIAS = 1µF, C1 = C2 = 1µF, speaker load
terminated between OUT_+ and OUT_-, headphone load terminated between HPOUT_ and GND, VGAIN1 = VGAIN2 = VVOL = VGAIN = 0V,
TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
LOGIC INPUT (SHDN, GAIN1, GAIN2, GAIN, VOL, IN1/2)
Logic Input High Voltage VIH 2V
Logic Input Low Voltage VIL 0.8 V
Logic Input Current IIN ±1µA
LOGIC INPUT HEADPHONE (HPS)
Logic Input High Voltage VIH 2V
Logic Input Low Voltage VIL 0.8 V
Logic Input Current IIN 10 µA
Note 1: All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design.
Note 2: Guaranteed by design. Not production tested.
Note 3: PSRR is specified with the amplifier input connected to GND through CIN.
Note 4: Output power levels are measured with the thin QFN’s exposed paddle soldered to the ground plane.
Note 5: See Table 3 for details of the mute levels.
Note 6: The value of RBdictates the minimum beep signal amplitude (see the
Beep Input
section).
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
6 _______________________________________________________________________________________
Typical Operating Characteristics
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
10
1
0.1
0.01
0.001
0.0001
10 1k 10k100 100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9750/51 toc01
FREQUENCY (Hz)
THD+N (%)
VCC = 5V
RL = 3Ω
AV = 10.5dB
OUTPUT POWER = 1.5W
OUTPUT POWER = 500mW
10
1
0.1
0.01
0.001
0.0001
10 1k 10k100 100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9750/51 toc02
FREQUENCY (Hz)
THD+N (%)
VCC = 5V
RL = 4Ω
AV = 10.5dB
OUTPUT POWER = 1.25W
OUTPUT POWER = 500mW
10
1
0.1
0.01
0.001
0.0001
10 1k 10k100 100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9750/51 toc03
FREQUENCY (Hz)
THD+N (%)
VCC = 5V
RL = 8Ω
AV = 10.5dB
OUTPUT POWER = 100mW
OUTPUT POWER = 600mW
100
0 0.5 1.0 1.5 2.0 2.5 3.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9750/51 toc04
OUTPUT POWER (W)
THD+N (%)
VCC = 5V
RL = 3Ω
AV = 10.5dB
MAX9750C
fIN = 10kHz
fIN = 1kHz
fIN = 20Hz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9750/51 toc05
OUTPUT POWER (W)
THD+N (%)
3.53.02.52.01.51.00.5
0.01
0.1
1
10
100
0.001
0
VDD = 5V
AV = 13.5dB
RL = 3Ω
f = 1kHz
f = 10kHz
f = 20Hz
100
00.5 1.0 1.5 2.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9750/51 toc06
OUTPUT POWER (W)
THD+N (%)
fIN = 1kHz
fIN = 20Hz
VCC = 5V
RL = 4Ω
AV = 10.5dB
MAX9750C
fIN = 10kHz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9750/51 toc07
OUTPUT POWER (W)
THD+N (%)
2.52.01.51.00.5
0.01
0.1
1
10
100
0.001
0 3.0
VDD = 5V
AV = 13.5dB
RL = 4Ω
f = 1kHz
f = 10kHz
f = 20Hz
100
00.2 0.4 0.6 0.8 1.0 1.2
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9750/51 toc08
OUTPUT POWER (W)
THD+N (%)
fIN = 20Hz fIN = 1kHz
fIN = 10kHz
VCC = 5V
RL = 8Ω
AV = 10.5dB
MAX9750C
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
_______________________________________________________________________________________
7
OUTPUT POWER
vs. LOAD RESISTANCE (SPEAKER MODE)
MAX9750/51 toc10
LOAD RESISTANCE (Ω)
OUTPUT POWER (W)
10
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
1 100
THD+N = 10%
THD+N = 1%
OUTPUT POWER
vs. LOAD RESISTANCE (SPEAKER MODE)
MAX9750/51 toc11
LOAD RESISTANCE (Ω)
OUTPUT POWER (W)
3.0
0
0.5
1.0
1.5
2.0
2.5
1 10 100
THD+N = 10%
THD+N = 1%
VCC = 5V
f = 1kHz
AV = 10.5dB
MAX9750C
POWER DISSIPATION vs. OUTPUT POWER
(SPEAKER MODE)
MAX9750/51 toc12
OUTPUT POWER (W)
POWER DISSIPATION (W)
321
1
2
3
4
5
0
04
RL = 4Ω
RL = 8Ω
VDD = 5V
f = 1kHz
POUT = POUTL + POUTR
POWER DISSIPATION vs. OUTPUT POWER
(SPEAKER MODE)
MAX9750/51 toc13
OUTPUT POWER (W)
POWER DISSIPATION (W)
3.53.02.52.01.51.00.5
1
2
3
4
5
0
0 4.0
RL = 4Ω
RL = 8Ω
VDD = 5V
f = 1kHz
POUT = POUTL + POUTR
MAX9750C
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY (SPEAKER MODE)
MAX9750/51 toc14
FREQUENCY (Hz)
PSRR (dB)
10k1k100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
10 100k
VRIPPLE = 200mVP-P
AV = 10.5dB
OUTPUT REFERRED
0
-120
10 1k 10k100 100k
CROSSTALK vs. FREQUENCY
(SPEAKER MODE)
MAX9750/51 toc15
FREQUENCY (Hz)
CROSSTALK (dB)
-100
-110
-80
-90
-60
-70
-40
-50
-20
-10
-30
VCC = 5V
VRIPPLE = 200mVP-P
RL = 4Ω
LEFT TO RIGHT
RIGHT TO LEFT
TURN-ON RESPONSE
(SPEAKER MODE)
MAX9750/51 toc16
20ms/div
SHDN
5V/div
2V/div
100mV/div
OUT_+
AND
OUT_-
OUT_+
- OUT_-
RL = 8Ω
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
8 _______________________________________________________________________________________
10
1
0.1
0.01
0.001
0.0001
10 1k 10k100 100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (HEADPHONE MODE)
MAX9750/51 toc19
FREQUENCY (Hz)
THD+N (%)
VDD = 5V
RL = 32Ω
AV = 3dB
OUTPUT POWER = 45mW
OUTPUT POWER = 10mW
10
1
0.1
0.01
0.001
0.0001
10 1k 10k100 100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (HEADPHONE MODE)
MAX9750/51 toc20
FREQUENCY (Hz)
THD+N (%)
VDD = 3.3V
RL = 16Ω
AV = 3dB
OUTPUT POWER = 30mW
OUTPUT POWER = 10mW
10
1
0.1
0.01
0.001
0.0001
10 1k 10k100 100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (HEADPHONE MODE)
MAX9750/51 toc21
FREQUENCY (Hz)
THD+N (%)
VDD = 3.3V
RL = 32Ω
AV = 3dB
OUTPUT POWER = 45mW
OUTPUT POWER = 10mW
1000
100
10
1
0.1
0.01
0.001
075
100 12550
25 150
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
MAX9750/51 toc22
OUTPUT POWER (mW)
THD+N (%)
VDD = 5V
RL = 16Ω
AV = 3dB
fIN = 10kHz
fIN = 1kHz
fIN = 20Hz
1000
100
10
1
0.1
0.01
0.001
0608040
20 100
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
MAX9750/51 toc23
OUTPUT POWER (mW)
THD+N (%)
VDD = 5V
RL = 32Ω
AV = 3dB
fIN = 10kHz
fIN = 1kHz
fIN = 20Hz
1000
100
10
1
0.1
0.01
0.001
030
40 5020
10 60
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
MAX9750/51 toc24
OUTPUT POWER (mW)
THD+N (%)
VDD = 3.3V
RL = 16Ω
AV = 3dB
fIN = 10kHz
fIN = 1kHz
fIN = 20Hz
TURN-OFF RESPONSE
(SPEAKER MODE)
MAX9750/51 toc17
20ms/div
SHDN
5V/div
2V/div
20mV/div
OUT_+
AND
OUT_-
OUT_+
- OUT_-
RL = 8Ω
10
1
0.1
0.01
0.001
0.0001
10 1k 10k100 100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (HEADPHONE MODE)
MAX9750/51 toc18
FREQUENCY (Hz)
THD+N (%)
VDD = 5V
RL = 16Ω
AV = 3dB
OUTPUT POWER = 90mW
OUTPUT POWER = 30mW
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
_______________________________________________________________________________________ 9
OUTPUT POWER vs. SUPPLY VOLTAGE
(HEADPHONE MODE)
MAX9750/51 toc28
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
5.04.54.03.5
25
50
75
100
125
0
3.0 5.5
RL = 16Ω
RL = 32Ω
f = 1kHz
10 1k 10k100 100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY (HEADPHONE MODE)
MAX9750/51 toc29
FREQUENCY (Hz)
PSRR (dB)
VRIPPLE = 200mVP-P
AV = 10.5dB
OUTPUT REFERRED
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
10 100 1k 10k 100k
CROSSTALK vs. FREQUENCY
(HEADPHONE MODE)
MAX9750/51 toc30
FREQUENCY (Hz)
CROSSTALK (dB)
VCC = 5V
VRIPPLE = 200mVP-P
RL = 32Ω
LEFT TO RIGHT
RIGHT TO LEFT
-100
-80
-60
-40
-20
0
-120
OUTPUT POWER vs. CHARGE-PUMP
CAPACITANCE AND LOAD RESISTANCE
MAX9750/51 toc31
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
403020
20
40
60
80
100
120
140
160
180
200
0
10 50
VDD = 5V
f = 1kHz
THD+N = 1%
C1 = C2 = 2.2μF
C1 = C2 = 1μF
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
OUTPUT POWER vs. LOAD RESISTANCE
(HEADPHONE MODE)
MAX9750/51 toc26
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
100
20
40
60
80
100
120
140
160
180
0
10 1000
THD+N = 10%
THD+N = 1%
POWER DISSIPATION vs. OUTPUT POWER
(HEADPHONE MODE)
MAX9750/51 toc27
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
225200150 17550 75 100 12525
25
50
75
100
125
150
175
200
225
250
0
0 250
VDD = 5V
f = 1kHz
POUT = POUTL + POUTR
RL = 16Ω
RL = 32Ω
1000
100
10
0.1
1
0.01
0.001
070
80
20 30 40 50 60
10 90
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
MAX9750/51 toc25
OUTPUT POWER (mW)
THD+N (%)
VDD = 3.3V
RL = 32Ω
AV = 3dB
fIN = 10kHz
fIN = 1kHz
fIN = 20Hz
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
10 ______________________________________________________________________________________
HEADPHONE OUTPUT SPECTRUM
MAX9750/51 toc32
FREQUENCY (Hz)
MAGNITUDE (dB)
15105
0
020
-120
-100
-80
-60
-40
-20
-140
VDD = 5V
f = 1kHz
VOUT = -60dB
RL = 32Ω
TURN-ON RESPONSE
(HEADPHONE MODE)
MAX9750/51 toc33
10ms/div
SHDN
5V/div
20mV/div
HPOUT_
RL = 32Ω
TURN-OFF RESPONSE
(HEADPHONE MODE)
MAX9750/51 toc34
10ms/div
SHDN
5V/div
20mV/div
HPOUT_
RL = 32Ω
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9750/51 toc35
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.255.004.75
4
2
6
8
12
10
14
16
18
0
4.50 5.50
HPS = GND
HPS = VDD
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9750/51 toc36
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (μA)
5.255.004.754.50 5.50
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 11
Pin Description
PIN
MAX9750 MAX9751 MAX9755
NAME FUNCTION
1 — 2 INL Left-Channel Audio Input
2 — — BEEP Audible Alert Beep Input
3, 19 3, 19 3, 19 PGND Power Ground. Connect PGND to GND at a single point on the PCB near
the device.
4 4 4 OUTL+ Left-Channel Positive Speaker Output
5 5 5 OUTL- Left-Channel Negative Speaker Output
6, 16 6, 16 6, 16 PV
DD
Speaker Amplifier Power Supply
7 7 7 CPV
DD
Charge-Pump Power Supply
8 8 8 C1P Charge-Pump Flying-Capacitor Positive Terminal
9 9 9 CPGND Charge-Pump Ground. Connect CPGND to PGND.
10 10 10 C1N Charge-Pump Flying-Capacitor Negative Terminal
11 11 11 CPV
SS
Charge-Pump Output. Connect to V
SS
.
12 12 12 V
SS
Headphone Amplifier Negative Power Supply
13 13 13 HPOUTR Right-Channel Headphone Output
14 14 14 HPOUTL Left-Channel Headphone Output
15 15 15 HPV
DD
Headphone Positive Power Supply
17 17 17 OUTR- Right-Channel Negative Speaker Output
18 18 18 OUTR+ Right-Channel Positive Speaker Output
20 20 20 HPS Headphone Sense Input
21 21 21 BIAS Common-Mode Bias Voltage. Bypass with a 1µF capacitor to GND.
22 22 22 SHDN Shutdown. Drive SHDN low to disable the device. Connect SHDN to V
DD
for normal operation.
23 — — GAIN2 Gain Control Input 2
24 — — GAIN1 Gain Control Input 1
25 25 25 V
DD
Power Supply
26 26 23, 26 GND Ground. Connect GND to PGND at a single point on the PCB near the
device.
27 — 28 INR Right-Channel Audio Input
28 — — VOL Analog Volume Control Input
— 1 — INL1 Left-Channel Audio Input 1
— 2 — INL2 Left-Channel Audio Input 2
— 23 — IN1/2Input Select
— 24 24 GAIN Gain Select
— 27 — INR1 Right-Channel Audio Input 1
— 28 — INR2 Right-Channel Audio Input 2
— — 1, 27 N.C. No Connection. Not internally connected.
— — 1, 27 N.C. No Connection. Not internally connected.
EP EP EP EP Exposed Paddle. Connect to GND.
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
12 ______________________________________________________________________________________
Detailed Description
The MAX9750/MAX9751/MAX9755 combine a 2.6W BTL
speaker amplifier and a 110mW DirectDrive headphone
amplifier with integrated headphone sensing and com-
prehensive click-and-pop suppression. The MAX9750
features an analog volume control, BEEP input, and
four-level gain control. The MAX9751 features a 2:1
input stereo multiplexer and two-level gain control. All
devices feature high 90dB PSRR, low 0.01% THD+N,
industry-leading click-pop performance, and a low-
power shutdown mode.
Each signal path consists of an input amplifier that sets
the gain of the signal path and feeds both the speaker
and headphone amplifier (Figure 1). The speaker
amplifier uses a BTL architecture, doubling the voltage
drive to the speakers and eliminating the need for DC-
blocking capacitors. The output consists of two signals,
identical in magnitude, but 180° out of phase.
The headphone amplifiers use Maxim’s DirectDrive
architecture that eliminates the bulky output DC-block-
ing capacitors required by traditional headphone ampli-
fiers. A charge pump inverts the positive supply
(CPVDD), creating a negative supply (CPVSS). The
headphone amplifiers operate from these bipolar sup-
plies with their outputs biased about GND (Figure 2).
The amplifiers have almost twice the supply range
compared to other single-supply amplifiers, nearly qua-
drupling the available output power. The benefit of the
GND bias is that the amplifier outputs no longer have a
DC component (typically VDD / 2). This eliminates the
large DC-blocking capacitors required with convention-
al headphone amplifiers, conserving board space and
system cost, and improving frequency response.
The MAX9750 features an analog volume control that
varies the gain of the amplifiers based on the DC volt-
age applied at VOL. Both devices feature an undervolt-
age lockout that prevents operation from an insufficient
power supply and click-and-pop suppression that elim-
inates audible transients on startup and shutdown. The
amplifiers include thermal-overload and short-circuit
protection, and can withstand ±8kV ESD strikes on the
headphone amplifier outputs (IEC air discharge). An
additional feature of the speaker amplifiers is that there
is no phase inversion from input to output.
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 headphones. Without these capacitors, a
OUT_+
OUT_
VOLUME
CONTROL BIAS
IN_
VOL
BIAS
MAX9750 ONLY
BIAS
HPOUT_
GND
Figure 1. MAX9750/MAX9751 Signal Path
+VDD
-VDD
GND
CONVENTIONAL DRIVER-BIASING SCHEME
DirectDrive BIASING SCHEME
VDD/2
VDD
GND
VOUT
Figure 2. Traditional Headphone Amplifier Output Waveform
vs. DirectDrive Headphone Amplifier Output Waveform
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 13
significant amount of DC current flows to the headphone,
resulting in unnecessary power dissipation and possible
damage to both headphone and headphone amplifier.
Maxim’s DirectDrive architecture uses a charge pump to
an internal negative supply voltage. This allows the
MAX9750/MAX9751/MAX9755 headphone amplifier out-
put to be biased about GND, almost doubling the dynam-
ic range while operating from a single supply. With no DC
component, there is no need for the large DC-blocking
capacitors. Instead of two large capacitors (220µF typ),
the MAX9750/MAX9751/MAX9755 charge pump requires
only two small ceramic capacitors (1µF typ), conserving
board space, reducing cost, and improving the frequen-
cy response of the headphone amplifier. See the Output
Power vs. Charge-Pump Capacitance and Load
Resistance graph in the
Typical Operating
Characteristics
for details of the possible capacitor val-
ues.
Previous attempts to eliminate the output coupling
capacitors involved biasing the headphone return
(sleeve) to the DC bias voltage of the headphone
amplifiers. This method raised some issues:
1) The sleeve is typically grounded to the chassis. Using
this biasing approach, the sleeve must be isolated
from system ground, complicating product design.
2) During an ESD strike, the amplifier’s ESD structures
are the only path to system ground. The amplifier
must be able to withstand the full ESD strike.
3) When using the headphone jack as a lineout to other
equipment, the bias voltage on the sleeve may con-
flict with the ground potential from other equipment,
resulting in large ground-loop current and possible
damage to the amplifiers.
Low-Frequency Response
In addition to the cost and size disadvantages, the DC-
blocking capacitors limit the low-frequency response of
the amplifier and distort the audio signal:
1) The impedance of the headphone load to the DC-
blocking capacitor forms a highpass filter with the
-3dB point determined by:
where RLis the impedance of the headphone and
COUT is the value of the DC-blocking capacitor.
The highpass filter is required by conventional sin-
gle-ended, single-supply headphone amplifiers to
block the midrail DC component of the audio signal
from the headphones. Depending on the -3dB point,
the filter can attenuate low-frequency signals within
the audio band. Larger values of COUT reduce the
attenuation but are physically larger, more expen-
sive capacitors. Figure 3 shows the relationship
between the size of COUT and the resulting low-fre-
quency attenuation. Note that the -3dB point for a
16Ωheadphone with a 100µF blocking capacitor is
100Hz, well within the audio band.
2) The voltage coefficient of the capacitor, the change
in capacitance due to a change in the voltage
across the capacitor, distorts the audio signal. At
frequencies around the -3dB point, the reactance of
the capacitor dominates, and the voltage coefficient
appears as frequency-dependent distortion. Figure
4 shows the THD+N introduced by two different
capacitor dielectrics. Note that around the -3dB
point, THD+N increases dramatically.
The combination of low-frequency attenuation and fre-
quency-dependent distortion compromises audio
reproduction. DirectDrive improves low-frequency
reproduction in portable audio equipment that empha-
sizes low-frequency effects such as multimedia lap-
tops, and MP3, CD, and DVD players.
Charge Pump
The MAX9750/MAX9751/MAX9755 feature a low-noise
charge pump. The 550kHz switching frequency is well
beyond the audio range, and does not interfere with the
audio signals. The switch drivers feature a controlled
switching speed that minimizes noise generated by turn-
on and turn-off transients. Limiting the switching speed of
the charge pump minimizes the di/dt noise caused by the
fRC
dB L OUT
−=
3
1
2π
0
-30
10 100 1k 10k 100k
LOW-FREQUENCY ROLLOFF
(RL = 16Ω)
-24
-27
-12
-15
-18
-21
-6
-9
-3
FREQUENCY (Hz)
ATTENUATION (dB)
DirectDrive
330μF
220μF
100μF
33μF
Figure 3. Low-Frequency Attenuation of Common DC-Blocking
Capacitor Values
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
14 ______________________________________________________________________________________
parasitic bond wire and trace inductance. Although not
typically required, additional high-frequency ripple atten-
uation can be achieved by increasing the size of C2 (see
the
Block Diagrams
).
Headphone Sense Input (HPS)
The headphone sense input (HPS) monitors the head-
phone jack and automatically configures the device
based upon the voltage applied at HPS. A voltage of
less than 0.8V sets the device to speaker mode. A volt-
age of greater than 2V disables the bridge amplifiers
and enables the headphone amplifiers.
For automatic headphone detection, connect HPS to the
control pin of a 3-wire headphone jack as shown in
Figure 5. With no headphone present, the output imped-
ance of the headphone amplifier pulls HPS low. When a
headphone plug is inserted into the jack, the control pin
is disconnected from the tip contact and HPS is pulled
to VDD through a 10µA current source.
BIAS
The MAX9750/MAX9751/MAX9755 feature an internally
generated, power-supply independent, common-mode
bias voltage of 1.8V referenced to GND. BIAS provides
both click-and-pop suppression and sets the DC bias
level for the amplifiers. Choose the value of the bypass
capacitor as described in the
BIAS Capacitor
section.
No external load should be applied to BIAS. Any load
lowers the BIAS voltage, affecting the overall perfor-
mance of the device.
Gain Selection
MAX9750
The MAX9750 features an internally set, selectable gain.
The GAIN1 and GAIN2 inputs set the maximum gain of
the MAX9750 speaker and headphone amplifiers (Table
1). The gain of the device can vary based upon the volt-
age at VOL (see the
Analog Volume Control (VOL)
sec-
tion). However, the maximum gain cannot be exceeded.
MAX9751/MAX9755
The gain of the MAX9751/MAX9755 is set by the GAIN
input. Driving GAIN high sets the gain of the speaker
amplifiers to 9dB and the gain of the headphone ampli-
fiers to 0dB. Driving GAIN low sets the gain of the
speaker amplifiers to 10.5dB, and the gain of the head-
phone amplifiers to 3dB (Table 2).
Analog Volume Control (VOL)
The MAX9750 features an analog volume control that
varies the gain of the device in 31 discrete steps based
upon the DC voltage applied to VOL. The input range of
VVOL is from 0 (full volume) to 0.858 x HPVDD (full mute),
with example step sizes shown in Table 3. Connect the
reference of the device driving VOL (Figure 6) to HPVDD.
Since the volume control ADC is ratiometric to HPVDD,
any changes in HPVDD are negated. The gain step sizes
are not constant; the step sizes are 0.5dB/step at the
upper extreme, 2dB/step in the midrange, and 4dB/step
at the lower extreme. Figure 7 shows the transfer function
of the volume control for a 3.3V supply.
ADDITIONAL THD+N DUE
TO DC-BLOCKING CAPACITORS
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.001
0.01
0.1
1
10
0.0001
10 100k
TANTALUM
ALUM/ELEC
Figure 4. Distortion Contributed by DC-Blocking Capacitors
MAX9750/
MAX9751/
MAX9755 10μA
1kΩ1kΩ
20
14
13
VDD
HPS
HPOUTL
HPOUTR
SHUTDOWN
CONTROL
Figure 5. HPS Configuration
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 15
BEEP Input
The MAX9750 features an audible alert beep input
(BEEP) that accepts a mono system alert signal and
mixes it into the stereo audio path. When the amplitude
of VBEEP(OUT) exceeds 800mVP-P (Figure 8) and the
frequency of the beep signal is greater than 300Hz, the
beep signal is mixed into the active audio path (speaker
or headphone). If the signal at VBEEP(OUT) is either
< 800mVP-P or < 300Hz, the BEEP signal is not mixed
into the audio path. The amplitude of the BEEP signal at
the device output is roughly the amplitude of VBEEP(OUT)
times the gain of the selected signal path.
The input resistor (RB) sets the gain of the BEEP input
amplifier, and thus the amplitude of VBEEP(OUT). Choose
RBbased on:
where RINT is the value of the BEEP amplifier feedback
resistor (47kΩ) and VIN is the BEEP input amplitude.
Note that the BEEP amplifier can be set up as either an
attenuator, if the original alert signal amplitude is too
large, or set to gain up the alert signal if it is below
800mVP-P. AC couple the alert signal to BEEP. Choose
the value of the coupling capacitor as described in the
Input Filtering
section. Multiple beep inputs can be
summed (Figure 8).
Input Multiplexer
The MAX9751 features a 2:1 input multiplexer on each
amplifier, allowing input selection between two stereo
sources. The logic input IN1/2controls both multiplex-
ers. A logic high selects input IN_1 and a logic low
selects input IN_2.
Shutdown
The MAX9750/MAX9751/MAX9755 features a 0.2µA,
low-power shutdown mode that reduces quiescent cur-
rent consumption and extends battery life. Driving
SHDN low disables the drive amplifiers, bias circuitry,
and charge pump, and drives BIAS and all outputs to
GND. Connect SHDN to VDD for normal operation.
Click-and-Pop Suppression
Speaker Amplifier
The MAX9750/MAX9751/MAX9755 speaker amplifiers
feature Maxim’s comprehensive, industry-leading click-
and-pop suppression. During startup, the click-pop
suppression circuitry eliminates any audible transient
sources internal to the device. When entering shut-
down, both amplifier outputs ramp to GND quickly and
simultaneously.
RVR
BIN INT
.
≤×
03
MAX9750
VREF
DAC
HPVDD
VOL
Figure 6. Volume Control Circuit
GAIN SPEAKER MODE
GAIN (dB)
HEADPHONE
MODE GAIN (dB)
0 10.5 3
19 0
Table 2. MAX9751/MAX9755 Gain Settings
SPEAKER MODE GAIN (dB)
GAIN2 GAIN1 MAX9750A MAX9750B MAX9750C HEADPHONE MODE GAIN (dB)
009 15 6 0
01 10.5 16.5 7.5 0
1012 18 9 3
11 13.5 19.5 10.5 3
Table 1. MAX9750 Maximum Gain Settings
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
16 ______________________________________________________________________________________
VVOL (V) SPEAKER MODE GAIN (dB) HEADPHONE MODE GAIN (dB)
VMIN*V
MAX* HPVDD*GAIN1 = 0,
GAIN2 = 0
GAIN1 = 1,
GAIN2 = 0
GAIN1 = 0,
GAIN2 = 1
GAIN1 = 1
GAIN2 = 1
GAIN1 = X,
GAIN2 = 0
GAIN1 = X,
GAIN2 = 1
0 0.49 0.074 9 10.5 12 13.5 0 3
0.49 0.5673 0.160 8 10 11.5 13 -1 2.5
0.5673 0.6447 0.183 7 9 11 12.5 -2 2
0.6447 0.722 0.207 6 8 10.5 12 -3 1.5
0.722 0.7994 0.230 4 7 10 11.5 -5 1
0.7994 0.8767 0.253 2 6 9 11 -7 0
0.8767 0.9541 0.277 0 4 8 10.5 -9 -1
0.9541 1.0314 0.300 -2 2 7 10 -11 -2
1.0314 1.1088 0.324 -4 0 6 9 -13 -3
1.1088 1.1861 0.347 -6 -2 4 8 -15 -5
1.1861 1.2635 0.371 -8 -4 2 7 -17 -7
1.2635 1.3408 0.394 -10 -6 0 6 -19 -9
1.3408 1.4182 0.418 -12 -8 -2 4 -21 -11
1.4182 1.4955 0.441 -14 -10 -4 2 -23 -13
1.4955 1.5728 0.464 -16 -12 -6 0 -25 -15
1.5728 1.6502 0.488 -18 -14 -8 -2 -27 -17
1.6502 1.7275 0.511 -20 -16 -10 -4 -29 -19
1.7275 1.8049 0.535 -22 -18 -12 -6 -31 -21
1.8094 1.8822 0.558 -24 -20 -14 -8 -33 -23
1.8822 1.9596 0.582 -26 -22 -16 -10 -35 -25
1.9596 2.0369 0.605 -28 -24 -18 -12 -37 -27
2.0369 2.1143 0.628 -30 -26 -20 -14 -39 -29
2.1143 2.1916 0.652 -32 -28 -22 -16 -41 -31
2.1916 2.269 0.675 -34 -30 -24 -18 -43 -33
2.269 2.3463 0.699 -38 -32 -26 -20 -47 -35
2.3463 2.4237 0.722 -42 -34 -28 -22 -51 -37
2.4237 2.501 0.746 -46 -38 -30 -24 -55 -39
2.501 2.5783 0.769 -50 -42 -32 -26 -59 -41
2.5783 2.6557 0.793 -54 -46 -34 -28 -63 -43
2.6557 2.733 0.816 -58 -50 -38 -30 -67 -47
2.733 2.8104 0.839 -62 -54 -42 -32 -71 -51
2.8104 3.3 0.858 MUTE MUTE MUTE MUTE MUTE MUTE
Table 3A. MAX9750A Volume Levels
*
Based on HPVDD = 3.3V
X = Don’t care.
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 17
VVOL (V) SPEAKER MODE GAIN (dB) HEADPHONE MODE GAIN
(dB)
VMIN*V
MAX* HPVDD*GAIN1 = 0,
GAIN2 = 0
GAIN1 = 1,
GAIN2 = 0
GAIN1 = 0,
GAIN2 = 1
GAIN1 = 1
GAIN2 = 1
GAIN1 = X,
GAIN2 = 0
GAIN1 = X,
GAIN2 = 1
0 0.49 0.074 15 16.5 18 19.5 0 3
0.49 0.5673 0.160 14 16 17.5 19 -1 2.5
0.5673 0.6447 0.183 13 15 17 18.5 -2 2
0.6447 0.722 0.207 12 14 16.5 18 -3 1.5
0.722 0.7994 0.230 10 13 16 17.5 -5 1
0.7994 0.8767 0.253 8 12 15 17 -7 0
0.8767 0.9541 0.277 6 10 14 16.5 -9 -1
0.9541 1.0314 0.300 4 8 13 16 -11 -2
1.0314 1.1088 0.324 2 6 12 15 -13 -3
1.1088 1.1861 0.347 0 4 10 14 -15 -5
1.1861 1.2635 0.371 -2 2 8 13 -17 -7
1.2635 1.3408 0.394 -4 0 6 12 -19 -9
1.3408 1.4182 0.418 -6 -2 4 10 -21 -11
1.4182 1.4955 0.441 -8 -4 2 8 -23 -13
1.4955 1.5728 0.464 -10 -6 0 6 -25 -15
1.5728 1.6502 0.488 -12 -8 -2 4 -27 -17
1.6502 1.7275 0.511 -14 -10 -4 2 -29 -19
1.7275 1.8049 0.535 -16 -12 -6 0 -31 -21
1.8049 1.8822 0.558 -18 -14 -8 -2 -33 -23
1.8822 1.9596 0.582 -20 -16 -10 -4 -35 -25
1.9596 2.0369 0.605 -22 -18 -12 -6 -37 -27
2.0369 2.1143 0.628 -24 -20 -14 -8 -39 -29
2.1143 2.1916 0.652 -26 -22 -16 -10 -41 -31
2.1916 2.269 0.675 -28 -24 -18 -12 -43 -33
2.269 2.3463 0.699 -32 -26 -20 -14 -47 -35
2.3463 2.4237 0.722 -36 -28 -22 -16 -51 -37
2.4237 2.501 0.746 -40 -32 -24 -18 -55 -39
2.501 2.5783 0.769 -44 -36 -26 -20 -59 -41
2.5783 2.6557 0.793 -48 -40 -28 -22 -63 -43
2.6557 2.733 0.816 -52 -44 -32 -24 -67 -47
2.733 2.8104 0.839 -56 -48 -36 -26 -71 -51
2.8104 3.3 0.858 MUTE MUTE MUTE MUTE MUTE MUTE
Table 3B. MAX9750B Volume Levels
*
Based on HPVDD = 3.3V
X = Don’t care.
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
18 ______________________________________________________________________________________
VVOL (V) SPEAKER MODE GAIN (dB) HEADPHONE MODE GAIN (dB)
VMIN*V
MAX* HPVDD*GAIN1 = 0,
GAIN2 = 0
GAIN1 = 1,
GAIN2 = 0
GAIN1 = 0,
GAIN2 = 1
GAIN1 = 1
GAIN2 = 1
GAIN1 = X,
GAIN2 = 0
GAIN1 = X,
GAIN2 = 1
0 0.49 0.074 6 7.5 9 10.5 0 3
0.49 0.5673 0.160 5 7 8.5 10 -1 2.5
0.5673 0.6447 0.183 4 6 8 9.5 -2 2
0.6447 0.722 0.207 3 5 7.5 9 -3 1.5
0.722 0.7994 0.230 1 4 7 8.5 -5 1
0.7994 0.8767 0.253 -1 3 6 8 -7 0
0.8767 0.9541 0.277 -3 1 5 7.5 -9 -1
0.9541 1.0314 0.300 -5 -1 4 7 -11 -2
1.0314 1.1088 0.324 -7 -3 3 6 -13 -3
1.1088 1.1861 0.347 -9 -5 1 5 -15 -5
1.1861 1.2635 0.371 -11 -7 -1 4 -17 -7
1.2635 1.3408 0.394 -13 -9 -3 3 -19 -9
1.3408 1.4182 0.418 -15 -11 -5 1 -21 -11
1.4182 1.4955 0.441 -17 -13 -7 -1 -23 -13
1.4955 1.5728 0.464 -19 -15 -9 -3 -25 -15
1.5728 1.6502 0.488 -21 -17 -11 -5 -27 -17
1.6502 1.7275 0.511 -23 -19 -13 -7 -29 -19
1.7275 1.8049 0.535 -25 -21 -15 -9 -31 -21
1.8049 1.8822 0.558 -27 -23 -17 -11 -33 -23
1.8822 1.9596 0.582 -29 -25 -9 -13 -35 -25
1.9596 2.0369 0.605 -31 -27 -21 -15 -37 -27
2.0369 2.1143 0.628 -33 -29 -23 -17 -39 -29
2.1143 2.1916 0.652 -35 -31 -2 -19 -41 -31
2.1916 2.269 0.675 -37 -3 -27 -21 -43 -33
2.269 2.3463 0.699 -41 -35 -29 -23 -47 -35
2.3463 2.4237 0.722 -45 -37 -31 -25 -51 -37
2.4237 2.501 0.746 -48 -41 -33 -27 -55 -39
2.501 2.5783 0.769 -53 -45 -35 -29 -59 -41
2.5783 2.6557 0.793 -57 -49 -37 -31 -63 -43
2.6557 2.733 0.816 -61 -53 -41 -33 -67 -47
2.733 2.8104 0.839 -65 -57 -45 -35 -71 -51
2.8104 3.3 0.858 MUTE MUTE MUTE MUTE MUTE MUTE
Table 3C. MAX9750C Volume Levels
*
Based on HPVDD = 3.3V
X = Don’t care.
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 19
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-
cally half the supply. Likewise, during shutdown, the
capacitor is discharged to GND. A DC shift across the
capacitor results, which in turn appears as an audible
transient at the speaker. Since the MAX9750/MAX9751/
MAX9755 do not require output-coupling capacitors, no
audible transient occurs.
Additionally, the MAX9750/MAX9751/MAX9755 features
extensive click-and-pop suppression that eliminates
any audible transient sources internal to the device.
The Turn-On Response (Headphone Mode) and Turn-
Off Response (Headphone Mode) graphs in the
Typical
Operating Characteristics
shows that there are minimal
transient components in the audible range at the output
upon startup and shutdown.
Figure 7a. Volume Control Transfer Function
-80
-60
-70
-40
-50
-20
-30
-10
10
0
20
0 1.0 1.50.5 2.0 2.5 3.0 3.5 4.0
MAX9750A
VOLUME CONTROL TRANSFER FUNCTION
VVOL (V)
GAIN (dB)
AUDIO
TAPER POT
GAIN1 = GAIN2 = 0
SPEAKER MODE
HEADPHONE MODE
Figure 7b. Volume Control Transfer Function
-80
-60
-70
-40
-50
-20
-30
-10
10
0
20
0 1.0 1.50.5 2.0 2.5 3.0 3.5 4.0
MAX9750B
VOLUME CONTROL TRANSFER FUNCTION
VVOL (V)
GAIN (dB)
AUDIO
TAPER POT
GAIN1 = GAIN2 = 0
SPEAKER MODE
HEADPHONE MODE
Figure 7c. Volume Control Transfer Function
-80
-60
-70
-40
-50
-20
-30
-10
10
0
20
0 1.0 1.50.5 2.0 2.5 3.0 3.5 4.0
MAX9750C
VOLUME CONTROL TRANSFER FUNCTION
VVOL (V)
GAIN (dB)
AUDIO
TAPER POT
GAIN1 = GAIN2 = 0
SPEAKER MODE
HEADPHONE MODE
MAX9750
RB3
47kΩ
BEEP
0.47μF
SOURCE 3
RB2
47kΩ
0.47μF
SOURCE 2
RB1
47kΩ
0.47μF
SOURCE 1 RINT
47kΩ
BIAS
WINDOW
DETECTOR
(0.8VP-P THRESHOLD)
SPEAKER/HEADPHONE
AMPLIFER INPUTS
VOUT(BEEP)
FREQUENCY
DETECTOR
(300Hz THRESHOLD)
Figure 8. BEEP Input
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
20 ______________________________________________________________________________________
Applications Information
BTL Speaker Amplifiers
The MAX9750/MAX9751/MAX9755 feature speaker
amplifiers designed to drive a load differentially, a con-
figuration referred to as bridge-tied load (BTL). The BTL
configuration (Figure 9) offers advantages over the sin-
gle-ended configuration, where one side of the load is
connected to ground. Driving the load differentially
doubles the output voltage compared to a single-
ended amplifier under similar conditions. Thus, the
device’s differential gain is twice the closed-loop gain
of the input amplifier. The effective gain is given by:
Substituting 2 x VOUT(P-P) into the following equation
yields four times the output power due to double the
output voltage:
Since the differential outputs are biased at midsupply,
there is no net DC voltage across the load. This elimi-
nates the need for DC-blocking capacitors required for
single-ended amplifiers. These capacitors can be large
and expensive, can consume board space, and can
degrade low-frequency performance.
Power Dissipation and Heat Sinking
Under normal operating conditions, the MAX9750/
MAX9751/MAX9755 can dissipate a significant amount
of power. The maximum power dissipation for each
package is given in the
Absolute Maximum Ratings
under Continuous Power Dissipation, or can be calcu-
lated by the following equation:
where TJ(MAX) is +150°C, TAis the ambient tempera-
ture, and θJA is the reciprocal of the derating factor in
°C/W as specified in the
Absolute Maximum Ratings
section. For example, θJA of the thin QFN package is
+42°C/W. For optimum power dissipation, the exposed
paddle of the package should be connected to the
ground plane (see the
Layout and Grounding
section).
Output Power (Speaker Amplifier)
The increase in power delivered by the BTL configura-
tion directly results in an increase in internal power dis-
sipation over the single-ended configuration. The
maximum power dissipation for a given VDD and load is
given by the following equation:
If the power dissipation for a given application exceeds
the maximum allowed for a given package, either reduce
VDD, increase load impedance, decrease the ambient
temperature, or add heatsinking to the device. Large
output, supply, and ground PC board traces improve the
maximum power dissipation in the package.
PV
R
DISS MAX DD
L
()
=22
2
π
PTT
DISSPKG MAX J MAX A
JA
() ()
=−
θ
VV
PV
R
RMS OUT P P
OUT RMS
L
=
=
−()
22
2
AR
R
VD F
IN
=×2
+1 VOUT(P-P)
2 x VOUT(P-P)
VOUT(P-P)
-1
Figure 9. Bridge-Tied Load Configuration
OUTPUT POWER (mW)
THD+N (%)
125100755025
0.01
0.1
1
10
100
1000
0.001
0 150
VDD = 5V
RL = 16Ω
AV = 3dB
OUTPUTS IN PHASE
OUTPUTS 180° OUT OF PHASE
Figure 10. Total Harmonic Distortion Plus Noise vs. Output Power
with Inputs In/Out of Phase (Headphone Mode)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 21
Thermal-overload protection limits total power dissipa-
tion in these devices. When the junction temperature
exceeds +160°C, the thermal-protection circuitry dis-
ables the amplifier output stage. The amplifiers are
enabled once the junction temperature cools by 15°C.
This results in a pulsing output under continuous ther-
mal-overload conditions as the device heats and cools.
Output Power (Headphone Amplifier)
The headphone amplifiers have been 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
headroom of VSS. 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 10 shows
the two extreme cases for in and out of phase. In reality,
the available power lies between these extremes.
Power Supplies
The MAX9750/MAX9751/MAX9755 have different sup-
plies for each portion of the device, allowing for the opti-
mum combination of headroom and power dissipation
and noise immunity. The speaker amplifiers are pow-
ered from PVDD. PVDD ranges from 4.5V to 5.5V. The
headphone amplifiers are powered from HPVDD and
VSS. HPVDD is the positive supply of the headphone
amplifiers and ranges from 3V to 5.5V. VSS is the nega-
tive supply of the headphone amplifiers. Connect VSS to
CPVSS. The charge pump is powered by CPVDD.
CPVDD ranges from 3V to 5.5V and should be the same
potential as HPVDD. The charge pump inverts the volt-
age at CPVDD, and the resulting voltage appears at
CPVSS. The remainder of the device is powered by VDD.
Component Selection
Input Filtering
The input capacitor (CIN), in conjunction with the ampli-
fier input resistance (RIN), forms a highpass filter that
removes the DC bias from an incoming signal (see the
Block Diagrams
). The AC-coupling capacitor allows the
amplifier to bias the signal to an optimum DC level.
Assuming zero source impedance, the -3dB point of
the highpass filter is given by:
RIN is the amplifier’s internal input resistance value
given in the
Electrical Characteristics
table. Choose CIN
such that f-3dB is well below the lowest frequency of
interest. Setting f-3dB too high affects the amplifier’s
low-frequency response. Use capacitors with low-volt-
age coefficient dielectrics, such as tantalum or alu-
minum electrolytic. Capacitors with high-voltage
coefficients, such as ceramics, may result in increased
distortion at low frequencies.
BIAS Capacitor
BIAS is the output of the internally generated DC bias
voltage. The BIAS bypass capacitor, CBIAS, improves
PSRR and THD+N by reducing power supply and other
noise sources at the common-mode bias node, and
also generates the clickless/popless, startup/shutdown
DC bias waveforms for the speaker amplifiers. Bypass
BIAS with a 1µF capacitor to GND.
Charge-Pump Capacitor Selection
Use capacitors with an ESR less than 100mΩfor 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. Table 4
lists suggested manufacturers.
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. Increasing the value of C1 improves
load regulation and reduces the charge-pump output
resistance to an extent. See the Output Power vs.
Charge-Pump Capacitance and Load Resistance
graph in the
Typical Operating Characteristics
. Above
2.2µF, the on-resistance of the switches and the ESR of
C1 and C2 dominate.
Output Capacitor (C2)
The output capacitor value and ESR directly affect the
ripple at CPVSS. Increasing the value of C2 reduces
output ripple. Likewise, decreasing the ESR of C2
fRC
dB IN IN
−=
3
1
2π
SUPPLIER PHONE FAX WEBSITE
Taiyo Yuden 800-348-2496 847-925-0899 www.t-yuden.com
TDK 807-803-6100 847-390-4405 www.component.tdk.com
Table 4. Suggested Capacitor Manufacturers
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
22 ______________________________________________________________________________________
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. Charge-Pump Capacitance and Load Resistance
graph in the
Typical Operating Characteristics
.
CPV
DD
Bypass Capacitor (C3)
The CPVDD bypass capacitor (C3) lowers the output
impedance of the power supply and reduces the
impact of the MAX9750/MAX9751/MAX9755’s charge-
pump switching transients. Bypass CPVDD with C3, the
same value as C1, and place it physically close to
CPVDD and PGND (refer to the MAX9750 Evaluation Kit
for a suggested layout).
Powering Other Circuits from a
Negative Supply
An additional benefit of the MAX9750/MAX9751/
MAX9755 is the internally generated negative supply volt-
age (CPVSS). CPVSS is used by the MAX9750/
MAX9751/MAX9755 to provide the negative supply for
the headphone amplifiers. It can also be used to power
other devices within a design. Current draw from CPVSS
should be limited to 5mA, exceeding this affects the oper-
ation of the headphone amplifier. A typical application is
a negative supply to adjust the contrast of LCD modules.
When considering the use of CPVSS in this manner,
note that the charge-pump voltage of CPVSS is roughly
proportional to CPVDD and is not a regulated voltage.
The charge-pump output impedance plot appears in
the
Typical Operating Characteristics
.
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 head away
from the device. Good grounding improves audio per-
formance, minimizes crosstalk between channels, and
prevents any switching noise from coupling into the
audio signal. Connect CPGND, PGND and GND
together at a single point on the PC board. Route
CPGND and all traces that carry switching transients
away from GND, PGND, and the traces and compo-
nents in the audio signal path.
Connect all components associated with the charge
pump (C2 and C3) to the CPGND plane. Connect VSS
and CPVSS together at the device. Place the charge-
pump capacitors (C1, C2, and C3) as close to the
device as possible. Bypass HPVDD and PVDD with a
0.1µF capacitor to GND. Place the bypass capacitors
as close to the device as possible.
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, when compared to a 0Ωtrace, a 100mΩ
trace reduces the power delivered to a 4Ωload from
2.1W to 2W. Large output, supply, and GND traces also
improve the power dissipation of the device.
The MAX9750/MAX9751/MAX9755 thin QFN package
features an exposed thermal pad on its underside. This
pad lowers the package’s thermal resistance by provid-
ing 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 a
GND plane on the bottom of the PCB.
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 23
Simplified Block Diagrams (continued)
MAX9751 MAX9755
MUX
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
24 ______________________________________________________________________________________
HPVDD
HPS
INR
BIAS
VOL
GAIN1
GAIN2
BEEP
3V TO 5.5V CPVDD
C1P
C1N
CPVSS VSS GND PGND
C1
1μF
CBIAS
1μF
CIN
1μF
CIN
1μF
C2
1μF
1μF
C3
1μF
CPGND
INL
27
21
28
24
23
2
22
7
8
10
9
11 12 26 3, 19
1
10μF
3V TO 5.5V
6, 16
4
25
5
18
17
15
20
14
13
HPOUTL
HPOUTR
MAX9750
0.1μF
0.1μF
4.5V TO 5.5V
GAIN/
VOLUME
CONTROL
BTL
AMPLIFIER
RIGHT-CHANNEL
AUDIO INPUT
OUTR+
OUTR-
CHARGE
PUMP
GAIN/
VOLUME
CONTROL
HEADPHONE
DETECTION
BEEP
DETECTION
SHUTDOWN
CONTROL
GAIN/
VOLUME
CONTROL
BTL
AMPLIFIER
LEFT-CHANNEL
AUDIO INPUT
OUTL+
PVDD
4.5V TO 5.5V
VDD
OUTL-
VDD
VDD
VDD SHDN
RB
47kΩ
Block Diagrams
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 25
HPVDD
HPS
INR1
BIAS
GAIN
IN1/2
SHDN
3V TO 5.5V CPVDD
VDD
VDD
VDD
C1P
C1N
CVSS VSS GND PGND
C1
1μF
CBIAS
1μF
CIN
1μF
CIN
1μF
C2
1μF
1μF
CPGND
INL1
27
21
28
24
23
2
22
7
8
10
9
11 12 26 3, 19
1
10μF
3V TO 5.5V
6, 16
4
25
5
18
17
15
20
14
13
HPOUTL
HPOUTR
MAX9751
0.1μF
0.1μF
4.5V TO 5.5V
BTL
AMPLIFIER
RIGHT CHANNEL
AUDIO INPUT
INR2
CIN
1μF
RIGHT CHANNEL
AUDIO INPUT
OUTR+
OUTR-
CHARGE
PUMP
MUX AND
GAIN
CONTROL
HEADPHONE
DETECTION
SHUTDOWN
CONTROL
INPUT
MUX
INPUT
MUX
BTL
AMPLIFIER
LEFT CHANNEL
AUDIO INPUT CIN
1μFINL2
LEFT CHANNEL
AUDIO INPUT
OUTL+
PVDD
4.5V TO 5.5V
VDD
OUTL-
LOGIC PINS CONFIGURED FOR:
GAIN = 1, 9dB SPEAKER GAIN/0dB HEADPHONE GAIN.
IN1/2 = 1, SELECTED INPUT LINE 1.
SHDN = 1, PART ACTIVE.
C3
Block Diagrams (continued)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
26 ______________________________________________________________________________________
HPVDD
HPS
BIAS
GAIN
SHDN
3V TO 5.5V CPVDD
VDD
VDD
C1P
C1N
CPVSS VSS GND PGND
C1
1μF
CBIAS
1μF
C2
1μF
1μF
CPGND
21
28
24
2
22
7
8
10
9
11 12 23, 26 3, 19
10μF
3V TO 5.5V
6, 16
4
25
5
18
17
15
20
14
13
HPOUTL
HPOUTR
MAX9755
0.1μF
0.1μF
4.5V TO 5.5V
BTL
AMPLIFIER
INR
CIN
1μF
RIGHT CHANNEL
AUDIO INPUT
OUTR+
OUTR-
CHARGE
PUMP
GAIN
CONTROL
HEADPHONE
DETECTION
SHUTDOWN
CONTROL
BTL
AMPLIFIER
CIN
1μFINL
LEFT CHANNEL
AUDIO INPUT
OUTL+
PVDD
4.5V TO 5.5V
VDD
OUTL-
LOGIC PINS CONFIGURED FOR:
GAIN = 1, 9dB SPEAKER GAIN/0dB HEADPHONE GAIN.
SHDN = 1, PART ACTIVE.
C3
Block Diagrams (continued)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 27
CODEC
MAX4060
AUX_IN
BIAS
IN+
IN-
OUT
3V TO 5.5V
MAX9750
INR
4.5V TO 5.5V 3V TO 5.5V
INL
CPVDD
BIAS
BEEP
1μF
0.1μF
1μF1μF
1μF
1μF
1μF1μF
1μF
1μF
1μF
μC
2kΩ
2kΩ
C1P
C1N
GND PGND
SHDN
OUTL+
OUTL-
VOL
CPVSS
VSS
CPGND
OUTR+
GAIN1
GAIN2
OUTR-
HPS
HPOUTL
HPOUTR
VDD HPVDD
PVDD
10μF
HPVDD
33kΩ
System Diagrams
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
28 ______________________________________________________________________________________
CODEC
MAX4060
AUX_IN
BIAS
IN+
IN-
OUT
3V TO 5.5V
MAX9751
INL2
4.5V TO 5.5V 3V TO 5.5V
INL1
CPVDD
0.1μF
1μF1μF
1μF
1μF
1μF
1μF
1μF
μC
2kΩ
2kΩ
C1P
C1N
GND PGND
SHDN
OUTL+
OUTL-
OUTR+
IN1/2
GAIN
OUTR-
HPS
HPOUTL
HPOUTR
VDD HPVDD
PVDD
INR1
INR2
1μF
10μF
1μF
BIAS
CPVSS
VSS
CPGND
System Diagrams (continued)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 29
BIAS
HPS
PGND
OUTR+
OUTR-
PVDD
HPVDD
12+
+
+34567
21 20 19 18 17 16 15
INL
BEEP
PGND
OUTL+
OUTL-
PVDD
CPVDD
8
9
10
11
12
13
14
C1P
CPGND
C1N
CPVSS
VSS
HPOUTR
HPOUTL
28
27
26
25
24
23
22
VOL
INR
GND
VDD
GAIN1
GAIN2
SHDN
MAX9750
THIN QFN
TOP VIEW
THIN QFN
BIAS
HPS
PGND
OUTR+
OUTR-
PVDD
HPVDD
1234567
21 20 19 18 17 16 15
INL1
INL2
PGND
OUTL+
OUTL-
PVDD
CPVDD
8
9
10
11
12
13
14
C1P
CPGND
C1N
CPVSS
VSS
HPOUTR
HPOUTL
28
27
26
25
24
23
22
INR2
INR1
GND
VDD
GAIN
IN1/2
SHDN
MAX9751
THIN QFN
BIAS
HPS
PGND
OUTR+
OUTR-
PVDD
HPVDD
1234567
21 20 19 18 17 16 15
N.C.
INL
PGND
OUTL+
OUTL-
PVDD
CPVDD
8
9
10
11
12
13
14
C1P
CPGND
C1N
CPVSS
VSS
HPOUTR
HPOUTL
28
27
26
25
24
23
22
INR
N.C.
GND
VDD
GAIN
GND
SHDN
MAX9755
Pin Configurations
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
28 TQFN T2855N-1 21-0140
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
8 6/08 Removed TSSOP package 1, 2, 11, 20, 24, 25, 26, 29
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.
30
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