19-3006; Rev 8; 6/08
EVALUATION KIT
AVAILABLE
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
Features
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 architecture 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.
♦ No DC-Blocking Capacitors Required—Provides
Industry’s Most Compact Notebook Audio
Solution
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, logicselectable gain, and a headphone sense input. Industryleading 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 thermaloverload and output short-circuit protection, and are
specified over the extended -40°C to +85°C temperature range.
♦ High 90dB PSRR
Applications
Notebook PCs
Flat-Panel TVs
Tablet PCs
PC Displays
♦ PC2001 Compliant
♦ 5V Single-Supply Operation
♦ Class AB 2.6W Stereo BTL Speaker Amplifiers
♦ 110mW DirectDrive Headphone Amplifiers
♦ 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
Portable DVD Players LCD Projectors
Ordering Information
Simplified Block Diagrams
PINPACKAGE
MAXIMUM GAIN
(dB)
MAX9750AETI+
28 Thin QFN
13.5
MAX9750BETI+
28 Thin QFN
19.5
MAX9750CETI+
28 Thin QFN
10.5
MAX9751ETI+
28 Thin QFN
10.5
MAX9755ETI+
28 Thin QFN
10.5
PART*
+Denotes
a lead-free/RoHS-compliant package.
*All devices specified over the -40°C to +85°C temperature
range.
VOL
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
BEEP
MAX9750
Simplified Block Diagrams continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX9750/MAX9751/MAX9755
General Description
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
ABSOLUTE MAXIMUM RATINGS
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
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(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
Headphone Supply Voltage
VDD, PVDD
Inferred from PSRR test
4.5
5.5
V
CPVDD,
HPVDD
Inferred from PSRR test
3.0
5.5
V
Quiescent Supply Current
IDD
Shutdown Supply Current
ISHDN
Bias Voltage
VBIAS
Switching Time
Input Resistance
Turn-On Time
HPS = GND, speaker mode, RL = ∞
14
29
HPS = VDD, headphone mode, RL = ∞
7
13
SHDN = GND
tSW
Gain or input switching
RIN
Amplifier inputs
(Note 2)
MAX9750
MAX9751/MAX9755
mA
0.2
5
µA
1.7
1.8
1.9
V
10
4.5
20
6
10
tSON
µs
30
8.0
25
kΩ
ms
SPEAKER AMPLIFIER (HPS = GND)
Output Offset Voltage
Power-Supply Rejection Ratio
(Note 3)
2
VOS
PSRR
Measured
between OUT_+
and OUT_-,
TA = +25°C
MAX9750A/MAX9750B/
MAX9751/MAX9755
PVDD or VDD =
4.5V to 5.5V
(TA = +25°C)
MAX9750A/MAX9750B/
MAX9750C/MAX9751
MAX9755
±1
±15
±0.4
±6
mV
MAX9750C
75
72
90
90
f = 1kHz, VRIPPLE = 200mVP-P
80
f = 10kHz, VRIPPLE = 200mVP-P
55
_______________________________________________________________________________________
dB
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
(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
RL = 8Ω
Output Power (Note 4)
POUT
THD+N = 1%,
f = 1kHz,
TA = +25°C
RL = 4Ω
MAX9750A/
MAX9750B/
MAX9751/
MAX9755
MAX9750C
Total Harmonic Distortion Plus
Noise
THD+N
TYP
0.9
1.4
0.65
0.8
MAX9750A/
MAX9750B/
MAX9751/
MAX9755
MAX9750C
RL = 3Ω
MIN
MAX9750A/
MAX9750B/
MAX9751/
MAX9755
MAX9750C
MAX
UNITS
2.3
W
1.2
1.5
2.6
2.2
RL = 8Ω, POUT = 500mW, f = 1kHz
0.01
0.02
%
Noise
Vn
RL = 4Ω, POUT = 1W, f = 1kHz
RL = 8Ω, POUT = 500mW, BW = 22Hz to
22kHz
BW = 22Hz to 22kHz, A-weighted
22
µVRMS
Capacitive-Load Drive
CL
No 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
Signal-to-Noise Ratio
Slew Rate
SNR
SR
AVMAX(SPKR) MAX9750B
MAX9750C
Gain (MAX9751/MAX9755)
AV
dB
1.4
MAX9750A
Gain (Maximum Volume Setting)
96
GAIN1 = 0, GAIN2 = 0
9
GAIN1 = 1, GAIN2 = 0
10.5
GAIN1 = 0, GAIN2 = 1
12
GAIN1 = 1, GAIN2 = 1
13.5
GAIN1 = 0, GAIN2 = 0
15
GAIN1 = 1, GAIN2 = 0
16.5
GAIN1 = 0, GAIN2 = 1
18
GAIN1 = 1, GAIN2 = 1
19.5
GAIN1 = 0, GAIN2 = 0
6
GAIN1 = 1, GAIN2 = 0
7.5
GAIN1 = 0, GAIN2 = 1
9
GAIN1 = 1, GAIN2 = 1
10.5
GAIN = 1
9
GAIN = 0
10.5
dB
V/µs
dB
dB
_______________________________________________________________________________________
3
MAX9750/MAX9751/MAX9755
ELECTRICAL CHARACTERISTICS (continued)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
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
±2
±7
mV
HEADPHONE AMPLIFIER (HPS = VDD)
Output Offset Voltage
Power-Supply Rejection Ratio
(Note 3)
Output Power
Total Harmonic Distortion Plus
Noise
Signal-to-Noise Ratio
VOS
TA = +25°C
HPVDD = 3V to 5.5V, TA = +25°C
PSRR
POUT
THD+N
SNR
60
75
f = 1kHz, VRIPPLE = 200mVP-P
73
f = 10kHz, VRIPPLE = 200mVP-P
63
THD+N = 1%,
f = 1kHz, TA = +25°C
RL = 32Ω
40
dB
50
mW
RL = 16Ω
110
RL = 32Ω, POUT = 20mW, f = 1kHz
0.007
RL = 16Ω, POUT = 75mW, f = 1kHz
0.03
RL = 32Ω, POUT = 50mW, BW = 22Hz to
22kHz
101
dB
%
Noise
Vn
BW = 22Hz to 22kHz
11
µVRMS
Capacitive-Load Drive
CL
pF
No sustained oscillations
200
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
Slew Rate
SR
ESD
ESD
Gain
AV
IEC air discharge
dB
0.4
V/µs
±8
kV
GAIN2 = GAIN = 0, GAIN1 = X
3
GAIN2 = GAIN = 1, GAIN1 = X
0
dB
CHARGE PUMP
Charge-Pump Frequency
fOSC
500
550
600
kHz
VOLUME CONTROL (MAX9750_)
VOL Input Impedance
RVOL
VOL Input Hysteresis
Full Mute Input Voltage
(Note 5)
Channel Matching
AV = -25dB to +13.5dB
100
MΩ
10
mV
0.858 x
HPVDD
V
±0.2
dB
BEEP INPUT (MAX9750_)
Beep Signal Minimum Amplitude
VBEEP
Beep Signal Minimum Frequency
fBEEP
4
RB = 33kΩ (Note 6)
0.8
VP-P
300
Hz
_______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
(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
2
V
Logic Input Low Voltage
VIL
0.8
V
Logic Input Current
IIN
±1
µA
0.8
V
LOGIC INPUT HEADPHONE (HPS)
Logic Input High Voltage
VIH
Logic Input Low Voltage
VIL
Logic Input Current
IIN
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
2
V
10
µA
All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design.
Guaranteed by design. Not production tested.
PSRR is specified with the amplifier input connected to GND through CIN.
Output power levels are measured with the thin QFN’s exposed paddle soldered to the ground plane.
See Table 3 for details of the mute levels.
The value of RB dictates the minimum beep signal amplitude (see the Beep Input section).
_______________________________________________________________________________________
5
MAX9750/MAX9751/MAX9755
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
0.01
OUTPUT POWER = 1.25W
0.1
0.01
10k
100
1k
10k
10
100k
MAX9750/51 toc03
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
THD+N (%)
fIN = 10kHz
0.1
1
f = 10kHz
f = 1kHz
0.1
0.01
0.01
0.01
fIN = 20Hz
0.001
1.5
2.0
2.5
0
3.0
0.5
1.0
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
2.5
3.0
100
1
f = 10kHz
f = 1kHz
0.01
VCC = 5V
RL = 8Ω
AV = 10.5dB
MAX9750C
10
THD+N (%)
VDD = 5V
AV = 13.5dB
RL = 4Ω
1
fIN = 10kHz
0.1
f = 20Hz
fIN = 20Hz
0.5
1.0
1.5
2.0
OUTPUT POWER (W)
0.5
2.5
3.0
2.0
1.0
1.5
OUTPUT POWER (W)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
100
VDD = 5V
AV = 13.5dB
RL = 8Ω
10
1
f = 10kHz
f = 1kHz
0.1
fIN = 1kHz
0
0.2
0.4
0.6
0.8
OUTPUT POWER (W)
f = 20Hz
0.001
0.001
0
0
0.01
0.01
0.001
fIN = 1kHz
0.001
3.5
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9750/51 toc07
100
0.1
2.0
OUTPUT POWER (W)
OUTPUT POWER (W)
10
1.5
THD+N (%)
1.0
MAX9750/51 toc08
0.5
fIN = 10kHz
0.1
f = 20Hz
fIN = 1kHz
0.001
0
1
MAX9750/51 toc09
fIN = 20Hz
VCC = 5V
RL = 4Ω
AV = 10.5dB
MAX9750C
10
THD+N (%)
1
VDD = 5V
AV = 13.5dB
RL = 3Ω
10
100
MAX9750/51 toc05
100
MAX9750/51 toc04
VCC = 5V
RL = 3Ω
AV = 10.5dB
MAX9750C
MAX9750/51 toc06
FREQUENCY (Hz)
10
THD+N (%)
0.0001
10
100k
100
6
OUTPUT POWER = 600mW
0.0001
0.0001
1k
0.01
0.001
0.001
0.001
100
OUTPUT POWER = 100mW
0.1
OUTPUT POWER = 500mW
OUTPUT POWER = 500mW
10
VCC = 5V
RL = 8Ω
AV = 10.5dB
1
THD+N (%)
THD+N (%)
THD+N (%)
OUTPUT POWER = 1.5W
0.1
VCC = 5V
RL = 4Ω
AV = 10.5dB
1
10
MAX9750/51 toc02
VCC = 5V
RL = 3Ω
AV = 10.5dB
1
10
MAX9750/51 toc01
10
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
THD+N (%)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
1.0
1.2
0
0.5
1.0
OUTPUT POWER (W)
_______________________________________________________________________________________
1.5
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
OUTPUT POWER
vs. LOAD RESISTANCE (SPEAKER MODE)
OUTPUT POWER
vs. LOAD RESISTANCE (SPEAKER MODE)
THD+N = 10%
VCC = 5V
f = 1kHz
AV = 10.5dB
MAX9750C
2.5
OUTPUT POWER (W)
2.5
2.0
THD+N = 1%
1.5
1.0
2.0
THD+N = 10%
1.5
1.0
THD+N = 1%
0.5
0.5
0
0
10
1
100
10
POWER DISSIPATION vs. OUTPUT POWER
(SPEAKER MODE)
POWER DISSIPATION vs. OUTPUT POWER
(SPEAKER MODE)
RL = 4Ω
2
RL = 8Ω
1
VRIPPLE = 200mVP-P
AV = 10.5dB
OUTPUT REFERRED
-10
-20
-30
RL = 4Ω
3
0
MAX9750/51 toc13
VDD = 5V
f = 1kHz
POUT = POUTL + POUTR
MAX9750C
4
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY (SPEAKER MODE)
PSRR (dB)
3
5
POWER DISSIPATION (W)
MAX9750/51 toc12
VDD = 5V
f = 1kHz
POUT = POUTL + POUTR
2
-40
-50
-60
-70
RL = 8Ω
1
-80
-90
0
0
0
1
2
0
4
3
-100
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
10
OUTPUT POWER (W)
OUTPUT POWER (W)
100
1k
10k
100k
FREQUENCY (Hz)
TURN-ON RESPONSE
(SPEAKER MODE)
CROSSTALK vs. FREQUENCY
(SPEAKER MODE)
MAX9750/51 toc15
MAX9750/51 toc16
0
VCC = 5V
VRIPPLE = 200mVP-P
RL = 4Ω
-10
-20
CROSSTALK (dB)
POWER DISSIPATION (W)
5
100
LOAD RESISTANCE (Ω)
LOAD RESISTANCE (Ω)
MAX9750/51 toc14
1
4
MAX9750/51 toc11
3.0
OUTPUT POWER (W)
3.0
MAX9750/51 toc10
3.5
-30
-40
-50
5V/div
SHDN
OUT_+
AND
OUT_-
-60
-70
-80
2V/div
LEFT TO RIGHT
-90
-100
-110
OUT_+
- OUT_-
RIGHT TO LEFT
100mV/div
RL = 8Ω
-120
10
100
1k
10k
100k
20ms/div
FREQUENCY (Hz)
_______________________________________________________________________________________
7
MAX9750/MAX9751/MAX9755
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
TURN-OFF RESPONSE
(SPEAKER MODE)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (HEADPHONE MODE)
MAX9750/51 toc17
VDD = 5V
RL = 16Ω
AV = 3dB
1
SHDN
MAX9750/51 toc18
10
5V/div
THD+N (%)
OUTPUT POWER = 90mW
OUT_+
AND
OUT_-
2V/div
OUT_+
- OUT_-
0.1
0.01
OUTPUT POWER = 30mW
20mV/div
0.001
RL = 8Ω
0.0001
10
20ms/div
100
1k
10k
100k
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (HEADPHONE MODE)
1
OUTPUT POWER = 30mW
THD+N (%)
0.1
0.01
OUTPUT POWER = 10mW
OUTPUT POWER = 10mW
0.001
100
1k
0.01
0.001
0.0001
0.0001
10
0.1
OUTPUT POWER = 10mW
0.001
10k
0.0001
10
100k
100
1k
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
THD+N (%)
1
fIN = 10kHz
10
fIN = 1kHz
1
fIN = 10kHz
0.1
0.1
0.01
0
25
50
75
100
OUTPUT POWER (mW)
125
150
fIN = 20Hz
fIN = 10kHz
0.01
0.001
0.001
fIN = 1kHz
1
0.1
fIN = 20Hz
0.01
fIN = 1kHz
fIN = 20Hz
VDD = 3.3V
RL = 16Ω
AV = 3dB
100
10
10
MAX9750/51 toc24
VDD = 5V
RL = 32Ω
AV = 3dB
100
1000
MAX9750/51 toc23
VDD = 5V
RL = 16Ω
AV = 3dB
100
1000
MAX9750/51 toc22
1000
8
OUTPUT POWER = 45mW
0.1
0.01
VDD = 3.3V
RL = 32Ω
AV = 3dB
1
THD+N (%)
THD+N (%)
OUTPUT POWER = 45mW
10
MAX9750/51 toc21
VDD = 3.3V
RL = 16Ω
AV = 3dB
THD+N (%)
VDD = 5V
RL = 32Ω
AV = 3dB
1
10
MAX9750/51 toc19
10
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (HEADPHONE MODE)
MAX9750/51 toc20
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (HEADPHONE MODE)
THD+N (%)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
0.001
0
20
40
60
OUTPUT POWER (mW)
80
100
0
10
20
30
40
OUTPUT POWER (mW)
_______________________________________________________________________________________
50
60
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
fIN = 10kHz
0.1
120
100
80
60
40
0.01
0.001
30
40
50
60 70
OUTPUT POWER (mW)
90
80
100
RL = 32Ω
75
VDD = 5V
f = 1kHz
POUT = POUTL + POUTR
0
10
0
1000
100
25 50 75 100 125 150 175 200 225 250
OUTPUT POWER (mW)
LOAD RESISTANCE (Ω)
OUTPUT POWER vs. SUPPLY VOLTAGE
(HEADPHONE MODE)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY (HEADPHONE MODE)
0
MAX9750/51 toc28
125
RL = 16Ω
100
MAX9750/51 toc27
125
VRIPPLE = 200mVP-P
AV = 10.5dB
OUTPUT REFERRED
-10
-20
-30
PSRR (dB)
75
RL = 32Ω
50
-40
-50
-60
-70
25
-80
-90
f = 1kHz
0
-100
0
3.5
4.0
4.5
5.0
10
100
1k
10k
100k
FREQUENCY (Hz)
CROSSTALK vs. FREQUENCY
(HEADPHONE MODE)
OUTPUT POWER vs. CHARGE-PUMP
CAPACITANCE AND LOAD RESISTANCE
VCC = 5V
VRIPPLE = 200mVP-P
RL = 32Ω
200
-40
-60
-80
RIGHT TO LEFT
VDD = 5V
f = 1kHz
THD+N = 1%
180
160
OUTPUT POWER (mW)
-20
5.5
SUPPLY VOLTAGE (V)
MAX9750/51 toc30
3.0
140
120
C1 = C2 = 2.2μF
100
80
60
C1 = C2 = 1μF
40
-100
MAX9750/51 toc31
20
OUTPUT POWER (mW)
10
150
25
0
0
175
50
THD+N = 1%
20
RL = 16Ω
200
MAX9750/51 toc29
fIN = 20Hz
225
POWER DISSIPATION (mW)
fIN = 1kHz
CROSSTALK (dB)
THD+N (%)
10
1
THD+N = 10%
140
250
MAX9750/51 toc26
160
OUTPUT POWER (mW)
VDD = 3.3V
RL = 32Ω
AV = 3dB
100
180
MAX9750/51 toc25
1000
POWER DISSIPATION vs. OUTPUT POWER
(HEADPHONE MODE)
OUTPUT POWER vs. LOAD RESISTANCE
(HEADPHONE MODE)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
20
LEFT TO RIGHT
-120
0
10
100
1k
FREQUENCY (Hz)
10k
100k
10
20
30
40
50
LOAD RESISTANCE (Ω)
_______________________________________________________________________________________
9
MAX9750/MAX9751/MAX9755
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
TURN-ON RESPONSE
(HEADPHONE MODE)
HEADPHONE OUTPUT SPECTRUM
MAX9750/51 toc33
MAX9750/51 toc32
0
VDD = 5V
f = 1kHz
VOUT = -60dB
RL = 32Ω
-20
MAGNITUDE (dB)
-40
5V/div
SHDN
-60
-80
20mV/div
HPOUT_
-100
-120
RL = 32Ω
-140
0
5
10
20
15
10ms/div
FREQUENCY (Hz)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
TURN-OFF RESPONSE
(HEADPHONE MODE)
MAX9750/51 toc34
16
20mV/div
HPOUT_
HPS = GND
14
SUPPLY CURRENT (mA)
SHDN
MAX9750/51 toc35
18
5V/div
12
HPS = VDD
10
8
6
4
2
RL = 32Ω
0
4.50
10ms/div
4.75
5.00
5.25
5.50
SUPPLY VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9750/51 toc36
0.35
0.30
SUPPLY CURRENT (μA)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
0.25
0.20
0.15
0.10
0.05
0
4.50
4.75
5.00
5.25
5.50
SUPPLY VOLTAGE (V)
10
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
NAME
PIN
MAX9750
MAX9751
FUNCTION
MAX9755
1
—
2
INL
2
—
—
BEEP
Left-Channel Audio Input
Audible Alert Beep Input
Power Ground. Connect PGND to GND at a single point on the PCB near
the device.
3, 19
3, 19
3, 19
PGND
4
4
4
OUTL+
Left-Channel Positive Speaker Output
5
5
5
OUTL-
Left-Channel Negative Speaker Output
6, 16
6, 16
6, 16
PVDD
Speaker Amplifier Power Supply
7
7
7
CPVDD
8
8
8
C1P
9
9
9
CPGND
Charge-Pump Ground. Connect CPGND to PGND.
10
10
10
C1N
Charge-Pump Flying-Capacitor Negative Terminal
11
11
11
CPVSS
Charge-Pump Power Supply
Charge-Pump Flying-Capacitor Positive Terminal
Charge-Pump Output. Connect to VSS.
12
12
12
VSS
13
13
13
HPOUTR
Headphone Amplifier Negative Power Supply
14
14
14
HPOUTL
15
15
15
HPVDD
Headphone Positive Power Supply
17
17
17
OUTR-
Right-Channel Negative Speaker Output
18
18
18
OUTR+
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 VDD
for normal operation.
23
—
—
GAIN2
Gain Control Input 2
24
—
—
GAIN1
25
25
25
VDD
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
—
IN1/2
Input 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
Right-Channel Headphone Output
Left-Channel Headphone Output
Right-Channel Positive Speaker Output
Gain Control Input 1
Exposed Paddle. Connect to GND.
______________________________________________________________________________________
11
MAX9750/MAX9751/MAX9755
Pin Description
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
MAX9750 ONLY
VDD
IN_
VOUT
VDD/2
GND
OUT_+
BIAS
BIAS
CONVENTIONAL DRIVER-BIASING SCHEME
+VDD
VOL
VOLUME
CONTROL
OUT_
BIAS
GND
HPOUT_
-VDD
GND
DirectDrive BIASING SCHEME
Figure 1. MAX9750/MAX9751 Signal Path
Detailed Description
The MAX9750/MAX9751/MAX9755 combine a 2.6W BTL
speaker amplifier and a 110mW DirectDrive headphone
amplifier with integrated headphone sensing and comprehensive 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 lowpower 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 DCblocking 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-blocking capacitors required by traditional headphone amplifiers. A charge pump inverts the positive supply
(CPV DD ), creating a negative supply (CPV SS ). The
headphone amplifiers operate from these bipolar supplies with their outputs biased about GND (Figure 2).
12
Figure 2. Traditional Headphone Amplifier Output Waveform
vs. DirectDrive Headphone Amplifier Output Waveform
The amplifiers have almost twice the supply range
compared to other single-supply amplifiers, nearly quadrupling 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 conventional 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 voltage applied at VOL. Both devices feature an undervoltage lockout that prevents operation from an insufficient
power supply and click-and-pop suppression that eliminates 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 (typically half the supply) for maximum dynamic range.
Large coupling capacitors are needed to block this DC
bias from the headphones. Without these capacitors, a
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
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 conflict 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 DCblocking capacitors limit the low-frequency response of
the amplifier and distort the audio signal:
1) The impedance of the headphone load to the DCblocking capacitor forms a highpass filter with the
-3dB point determined by:
f−3dB =
1
2πRLCOUT
where RL is the impedance of the headphone and
COUT is the value of the DC-blocking capacitor.
The highpass filter is required by conventional single-ended, single-supply headphone amplifiers to
block the midrail DC component of the audio signal
from the headphones. Depending on the -3dB point,
LOW-FREQUENCY ROLLOFF
(RL = 16Ω)
0
-3
DirectDrive
ATTENUATION (dB)
-6
-9
330μF
-12
220μF
-15
100μF
-18
33μF
-21
-24
-27
-30
10
100
1k
10k
100k
FREQUENCY (Hz)
Figure 3. Low-Frequency Attenuation of Common DC-Blocking
Capacitor Values
the filter can attenuate low-frequency signals within
the audio band. Larger values of COUT reduce the
attenuation but are physically larger, more expensive capacitors. Figure 3 shows the relationship
between the size of COUT and the resulting low-frequency attenuation. Note that the -3dB point for a
16Ω headphone 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 frequency-dependent distortion compromises audio
reproduction. DirectDrive improves low-frequency
reproduction in portable audio equipment that emphasizes low-frequency effects such as multimedia laptops, 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 turnon and turn-off transients. Limiting the switching speed of
the charge pump minimizes the di/dt noise caused by the
______________________________________________________________________________________
13
MAX9750/MAX9751/MAX9755
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 output to be biased about GND, almost doubling the dynamic 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 frequency 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 values.
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:
VDD
ADDITIONAL THD+N DUE
TO DC-BLOCKING CAPACITORS
MAX9750/
MAX9751/
MAX9755
10
1
THD+N (%)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
10μA
SHUTDOWN
CONTROL
20
HPS
0.1
14
HPOUTL
TANTALUM
0.01
13
HPOUTR
1kΩ
0.001
1kΩ
ALUM/ELEC
0.0001
10
100
1k
10k
100k
FREQUENCY (Hz)
Figure 4. Distortion Contributed by DC-Blocking Capacitors
parasitic bond wire and trace inductance. Although not
typically required, additional high-frequency ripple attenuation can be achieved by increasing the size of C2 (see
the Block Diagrams).
Headphone Sense Input (HPS)
The headphone sense input (HPS) monitors the headphone 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 voltage 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 impedance 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 performance of the device.
14
Figure 5. HPS Configuration
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 voltage at VOL (see the Analog Volume Control (VOL) section). 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 amplifiers to 0dB. Driving GAIN low sets the gain of the
speaker amplifiers to 10.5dB, and the gain of the headphone 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.
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
SPEAKER MODE GAIN (dB)
GAIN2
GAIN1
0
0
9
15
6
0
0
1
10.5
16.5
7.5
0
1
0
12
18
9
3
1
1
13.5
19.5
10.5
3
MAX9750A
MAX9750B
HEADPHONE MODE GAIN (dB)
MAX9750C
Table 2. MAX9751/MAX9755 Gain Settings
GAIN
SPEAKER MODE
GAIN (dB)
HEADPHONE
MODE GAIN (dB)
0
10.5
3
1
9
0
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
RB based on:
RB ≤
VIN × RINT
0.3
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).
MAX9750
HPVDD
VREF
DAC
VOL
Figure 6. Volume Control Circuit
Input Multiplexer
The MAX9751 features a 2:1 input multiplexer on each
amplifier, allowing input selection between two stereo
sources. The logic input IN1/2 controls both multiplexers. 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 current 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 clickand-pop suppression. During startup, the click-pop
suppression circuitry eliminates any audible transient
sources internal to the device. When entering shutdown, both amplifier outputs ramp to GND quickly and
simultaneously.
______________________________________________________________________________________
15
MAX9750/MAX9751/MAX9755
Table 1. MAX9750 Maximum Gain Settings
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
Table 3A. MAX9750A Volume Levels
VVOL (V)
VMIN*
SPEAKER MODE GAIN (dB)
VMAX*
HPVDD*
GAIN1 = 0,
GAIN2 = 0
GAIN1 = 1,
GAIN2 = 0
HEADPHONE MODE GAIN (dB)
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
*Based on HPVDD = 3.3V
X = Don’t care.
16
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
VVOL (V)
VMIN*
HEADPHONE MODE GAIN
(dB)
SPEAKER MODE GAIN (dB)
VMAX*
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
*Based on HPVDD = 3.3V
X = Don’t care.
______________________________________________________________________________________
17
MAX9750/MAX9751/MAX9755
Table 3B. MAX9750B Volume Levels
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
Table 3C. MAX9750C Volume Levels
VVOL (V)
VMIN*
SPEAKER MODE GAIN (dB)
VMAX*
HPVDD*
GAIN1 = 0,
GAIN2 = 0
GAIN1 = 1,
GAIN2 = 0
HEADPHONE MODE GAIN (dB)
GAIN1 = 0,
GAIN2 = 1
GAIN1 = 1
GAIN2 = 1
GAIN1 = X,
GAIN2 = 0
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
*Based on HPVDD = 3.3V
X = Don’t care.
18
GAIN1 = X,
GAIN2 = 1
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
MAX9750B
VOLUME CONTROL TRANSFER FUNCTION
20
20
GAIN1 = GAIN2 = 0
10
0
0
SPEAKER MODE
AUDIO
TAPER POT
-20
-30
-40
-50
SPEAKER MODE
-10
GAIN (dB)
-10
GAIN (dB)
GAIN1 = GAIN2 = 0
10
AUDIO
TAPER POT
-20
-30
-40
-50
HEADPHONE MODE
-60
-60
-70
-70
-80
HEADPHONE MODE
-80
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
0.5
1.0
VVOL (V)
GAIN1 = GAIN2 = 0
0
GAIN (dB)
SPEAKER MODE
AUDIO
TAPER POT
-30
-40
-50
HEADPHONE MODE
-60
-80
0.5
1.0
1.5
2.0
3.5
4.0
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 TurnOff 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.
-70
0
3.0
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, typically 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.
20
-20
2.5
Figure 7b. Volume Control Transfer Function
MAX9750C
VOLUME CONTROL TRANSFER FUNCTION
-10
2.0
VVOL (V)
Figure 7a. Volume Control Transfer Function
10
1.5
2.5
3.0
3.5
4.0
VVOL (V)
Figure 7c. Volume Control Transfer Function
0.47μF
RB1
47kΩ
RINT
47kΩ
SOURCE 1
0.47μF
RB2
47kΩ
0.47μF
RB3
47kΩ
SOURCE 2
BEEP
SOURCE 3
VOUT(BEEP)
SPEAKER/HEADPHONE
AMPLIFER INPUTS
WINDOW
DETECTOR
(0.8VP-P THRESHOLD)
BIAS
FREQUENCY
DETECTOR
(300Hz THRESHOLD)
MAX9750
Figure 8. BEEP Input
______________________________________________________________________________________
19
MAX9750/MAX9751/MAX9755
MAX9750A
VOLUME CONTROL TRANSFER FUNCTION
1000
VDD = 5V
RL = 16Ω
AV = 3dB
100
10
VOUT(P-P)
+1
2 x VOUT(P-P)
THD+N (%)
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
OUTPUTS IN PHASE
1
0.1
-1
VOUT(P-P)
0.01
OUTPUTS 180° OUT OF PHASE
0.001
0
25
50
75
100
125
150
OUTPUT POWER (mW)
Figure 9. Bridge-Tied Load Configuration
Applications Information
BTL Speaker Amplifiers
The MAX9750/MAX9751/MAX9755 feature speaker
amplifiers designed to drive a load differentially, a configuration referred to as bridge-tied load (BTL). The BTL
configuration (Figure 9) offers advantages over the single-ended configuration, where one side of the load is
connected to ground. Driving the load differentially
doubles the output voltage compared to a singleended 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:
A VD = 2 ×
RF
RIN
Substituting 2 x VOUT(P-P) into the following equation
yields four times the output power due to double the
output voltage:
VRMS =
VOUT(P−P)
2 2
2
V
POUT = RMS
RL
Since the differential outputs are biased at midsupply,
there is no net DC voltage across the load. This eliminates 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.
20
Figure 10. Total Harmonic Distortion Plus Noise vs. Output Power
with Inputs In/Out of Phase (Headphone Mode)
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 calculated by the following equation:
PDISSPKG(MAX) =
TJ(MAX) − TA
θJA
where TJ(MAX) is +150°C, TA is the ambient temperature, 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 configuration directly results in an increase in internal power dissipation over the single-ended configuration. The
maximum power dissipation for a given VDD and load is
given by the following equation:
PDISS(MAX) =
2VDD2
π 2RL
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.
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
PHONE
FAX
Taiyo Yuden
SUPPLIER
800-348-2496
847-925-0899
www.t-yuden.com
TDK
807-803-6100
847-390-4405
www.component.tdk.com
Thermal-overload protection limits total power dissipation in these devices. When the junction temperature
exceeds +160°C, the thermal-protection circuitry disables the amplifier output stage. The amplifiers are
enabled once the junction temperature cools by 15°C.
This results in a pulsing output under continuous thermal-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 magnitude 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 supplies for each portion of the device, allowing for the optimum combination of headroom and power dissipation
and noise immunity. The speaker amplifiers are powered 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 negative supply of the headphone amplifiers. Connect VSS to
CPV SS . The charge pump is powered by CPV DD .
CPVDD ranges from 3V to 5.5V and should be the same
potential as HPVDD. The charge pump inverts the voltage 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 amplifier 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:
WEBSITE
f−3dB =
1
2πRINCIN
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-voltage coefficient dielectrics, such as tantalum or aluminum 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 100mΩ for optimum performance. Low-ESR ceramic capacitors minimize 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
______________________________________________________________________________________
21
MAX9750/MAX9751/MAX9755
Table 4. Suggested Capacitor Manufacturers
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
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.
CPVDD 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 chargepump 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 voltage (CPV SS ). CPV SS 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 operation 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.
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 components 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 chargepump 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 impedance decreases, the current drawn from the device outputs increase. At higher current, the resistance of the
output traces decrease the power delivered to the load.
For example, when compared to a 0Ω trace, a 100mΩ
trace reduces the power delivered to a 4Ω load 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 providing a direct heat conduction path from the die to the
printed circuit board. Connect the exposed thermal
pad to GND by using a large pad and multiple vias to a
GND plane on the bottom of the PCB.
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 performance, minimizes crosstalk between channels, and
prevents any switching noise from coupling into the
audio signal. Connect CPGND, PGND and GND
22
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
MUX
MAX9751
MAX9755
______________________________________________________________________________________
23
MAX9750/MAX9751/MAX9755
Simplified Block Diagrams (continued)
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
MAX9750/MAX9751/MAX9755
Block Diagrams
4.5V TO 5.5V
0.1μF
VDD
25
6, 16 PVDD
MAX9750
CIN
1μF
LEFT-CHANNEL
AUDIO INPUT
CIN
1μF
RIGHT-CHANNEL
AUDIO INPUT
INL 1
INR 27
4.5V TO 5.5V
0.1μF
4 OUTL+
GAIN/
VOLUME
CONTROL
BTL
AMPLIFIER
GAIN/
VOLUME
CONTROL
BTL
AMPLIFIER
5 OUTL-
18 OUTR+
17 OUTR-
BIAS 21
CBIAS
1μF
VOL 28
24
VDD GAIN1
RB VDD
47kΩ
1μF
GAIN2 23
HEADPHONE
DETECTION
BEEP 2
BEEP
DETECTION
22
VDD SHDN
20 HPS
3V TO 5.5V
10μF
14 HPOUTL
SHUTDOWN
CONTROL
13 HPOUTR
CPVDD 7
3V TO 5.5V
C3
1μF
15 HPVDD
GAIN/
VOLUME
CONTROL
C1P 8
C1
1μF
10
CHARGE
PUMP
C1N
CPGND 9
11
CPVSS
24
26
12
VSS
C2
1μF
3, 19
GND
PGND
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
4.5V TO 5.5V
0.1μF
VDD
25
6, 16 PVDD
MAX9751
CIN
LEFT CHANNEL 1μF
AUDIO INPUT CIN
LEFT CHANNEL 1μF
AUDIO INPUT
INL1 1
INL2 2
CIN
RIGHT CHANNEL 1μF
AUDIO INPUT C
IN
RIGHT CHANNEL 1μF
AUDIO INPUT
4 OUTL+
INPUT
MUX
BTL
AMPLIFIER
INPUT
MUX
BTL
AMPLIFIER
INR1 27
INR2 28
4.5V TO 5.5V
0.1μF
5 OUTL-
18 OUTR+
17 OUTR-
BIAS 21
CBIAS
1μF
15 HPVDD
GAIN 24
VDD
IN1/2 23
VDD
SHDN 22
VDD
20 HPS
3V TO 5.5V
10μF
14 HPOUTL
HEADPHONE
DETECTION
SHUTDOWN
CONTROL
13 HPOUTR
CPVDD 7
3V TO 5.5V
C3
1μF
MUX AND
GAIN
CONTROL
C1P 8
C1
1μF
10
CHARGE
PUMP
C1N
CPGND 9
11
12
CVSS
26
VSS
C2
1μF
3, 19
GND
PGND
LOGIC PINS CONFIGURED FOR:
GAIN = 1, 9dB SPEAKER GAIN/0dB HEADPHONE GAIN.
IN1/2 = 1, SELECTED INPUT LINE 1.
SHDN = 1, PART ACTIVE.
______________________________________________________________________________________
25
MAX9750/MAX9751/MAX9755
Block Diagrams (continued)
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
MAX9750/MAX9751/MAX9755
Block Diagrams (continued)
4.5V TO 5.5V
0.1μF
VDD
25
6, 16 PVDD
MAX9755
CIN
LEFT CHANNEL 1μF
AUDIO INPUT
INL 2
CIN
RIGHT CHANNEL 1μF
AUDIO INPUT
INR 28
4.5V TO 5.5V
0.1μF
4 OUTL+
BTL
AMPLIFIER
5 OUTL-
18 OUTR+
BTL
AMPLIFIER
17 OUTR-
BIAS 21
CBIAS
1μF
15 HPVDD
GAIN 24
VDD
GAIN
CONTROL
20 HPS
HEADPHONE
DETECTION
14 HPOUTL
SHDN 22
VDD
SHUTDOWN
CONTROL
13 HPOUTR
CPVDD 7
3V TO 5.5V
C3
1μF
3V TO 5.5V
10μF
C1P 8
C1
1μF
10
CHARGE
PUMP
C1N
CPGND 9
11
CPVSS
23, 26
12
VSS
C2
1μF
GND
3, 19
PGND
LOGIC PINS CONFIGURED FOR:
GAIN = 1, 9dB SPEAKER GAIN/0dB HEADPHONE GAIN.
SHDN = 1, PART ACTIVE.
26
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
4.5V TO 5.5V
3V TO 5.5V
10μF
0.1μF
VDD
PVDD
HPVDD
BIAS
OUTL+
1μF
OUTL-
MAX9750
1μF
1μF
AUX_IN
OUTR+
INL
1μF
OUT
OUTR-
CODEC
INR
1μF
2kΩ
HPOUTL
33kΩ
MAX4060
BEEP
BIAS
HPS
HPOUTR
2kΩ
SHDN
1μF
1μF
IN+
IN-
μC
HPVDD
GAIN1
3V TO 5.5V
1μF
GAIN2
VOL
CPVDD
CPVSS
VSS
C1P
1μF
1μF
CPGND
C1N
GND
PGND
______________________________________________________________________________________
27
MAX9750/MAX9751/MAX9755
System Diagrams
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
MAX9750/MAX9751/MAX9755
System Diagrams (continued)
4.5V TO 5.5V
3V TO 5.5V
10μF
0.1μF
VDD
PVDD
HPVDD
1μF
OUTL+
INL1
OUTL-
CODEC
INL2
MAX9751
1μF
AUX_IN
OUTR+
1μF
INR1
OUT
OUTR-
INR2
2kΩ
HPOUTL
MAX4060
BIAS
HPS
SHDN
μC
2kΩ
1μF
1μF
IN1/2
GAIN
IN+
3V TO 5.5V
IN-
HPOUTR
CPVSS
CPVDD
1μF
VSS
C1P
1μF
1μF
CPGND
C1N
BIAS
GND
28
PGND
1μF
______________________________________________________________________________________
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
SHDN
BIAS
HPS
PGND
OUTR+
OUTR-
PVDD
HPVDD
BIAS
HPS
PGND
OUTR+
OUTR-
PVDD
HPVDD
TOP VIEW
21
20
19
18
17
16
15
21
20
19
18
17
16
15
22
HPOUTL
SHDN
22
14
HPOUTL
13
HPOUTR
IN1/2
23
13
HPOUTR
12
VSS
GAIN
24
12
VSS
11
CPVSS
VDD
25
11
CPVSS
14
GAIN2
23
GAIN1
24
VDD
25
GND
26
10
C1N
GND
26
10
C1N
INR
27
9
CPGND
INR1
27
9
CPGND
VOL
28
8
C1P
INR2
28
8
C1P
BIAS
HPS
PGND
OUTR+
OUTR-
PVDD
HPVDD
21
20
19
18
17
16
15
4
5
6
PVDD
THIN QFN
SHDN
22
14
HPOUTL
GND
23
13
HPOUTR
GAIN
24
12
VSS
MAX9755
CPGND
INR
28
8
C1P
1
2
3
4
5
6
7
CPVDD
9
PVDD
27
OUTL-
C1N
N.C.
PGND
CPVSS
10
OUTL+
11
26
INL
25
N.C.
VDD
GND
+
7
CPVDD
3
OUTL-
PVDD
CPVDD
THIN QFN
2
PGND
7
1
OUTL+
6
+
INL2
5
MAX9751
INL1
4
OUTL-
BEEP
3
OUTL+
2
PGND
1
INL
+
MAX9750
THIN QFN
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
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
29
MAX9750/MAX9751/MAX9755
Pin Configurations
MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
Revision History
REVISION
NUMBER
REVISION
DATE
8
6/08
DESCRIPTION
Removed TSSOP package
PAGES
CHANGED
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 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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