19-3882; Rev 0; 10/05
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
General Description
The MAX9787 combines a stereo, 2.2W audio power
amplifier with an analog volume control in a single device.
A high 90dB PSRR and low 0.01% THD+N ensures clean,
low-distortion amplification of the audio signal.
The analog volume control can be driven with a poten-
tiometer, an RC-filtered PWM source, or a DAC output.
A BEEP input allows the addition of alert signals from
the controller to the audio path.
Industry-leading, click-and-pop suppression eliminates
audible transients during power and shutdown cycles.
Other features include single-supply voltage, a shut-
down mode, logic-selectable gain, thermal-overload,
and output short-circuit protection.
The MAX9787 is offered in a space-saving, thermally
efficient, 28-pin, thin QFN (5mm x 5mm x 0.8mm) pack-
age, and is specified over the extended -40°C to +85°C
temperature range.
♦
Analog Volume Control
♦
BEEP Input with Glitch Filter
♦
5V Single-Supply Operation
♦
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
♦
Space-Saving 28-Pin TQFN (5mm x 5mm x 0.8mm)
Features
♦
Class AB, 2.2W, Stereo BTL Speaker Amplifiers
MAX9787
Applications
Notebook PCs
Flat-Panel TVs
Tablet PCs
PC Displays
Portable DVD Players
LCD Projectors
Multimedia Monitors
PART
MAX9787ETI+
Ordering Information
PIN-PACKAGE
28 TQFN-EP*
PKG CODE
T2855N-1
Note:
This device is specified for -40°C to +85°C operation.
+Denotes
lead-free package.
*EP
= Exposed paddle.
Typical Operating Circuit
PGND
BIAS
Pin Configuration
OUTR-
PV
DD
PV
DD
GND
TOP VIEW
+5V
21
20
19
18
OUTR+
17
16
15
14
13
12
N.C.
N.C.
V
SS
CPV
SS
C1N
CPGND
C1P
Σ
Σ
BEEP
SHDN
GAIN2
GAIN1
V
DD
GND
INR
22
23
24
25
26
27
28
*EP
MAX9787
11
10
9
8
MAX9787
VOLUME
VOL
+
1
INL
2
BEEP
3
PGND
4
OUTL+
5
OUTL-
6
PV
DD
7
CPV
DD
*EXPOSED PAD.
THIN QFN
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
MAX9787
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V
DD
, PV
DD
, CPV
DD
to GND) .......................+6V
GND to PGND.....................................................................±0.3V
CPV
SS
, C1N, V
SS
to GND .........................-6.0V to (GND + 0.3V)
Any Other Pin .............................................-0.3V to (V
DD
+ 0.3V)
Duration of OUT_ Short Circuit to GND or PV
DD
........Continuous
Duration of OUT_+ Short Circuit to OUT_- .................Continuous
Continuous Current (PV
DD
, OUT_, PGND) ...........................1.7A
Continuous Current (CPV
DD
, C1N, C1P, CPV
SS,
V
SS
)......850mA
Continuous Input Current (all other pins) .........................±20mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin Thin QFN (derate 23.8mW/°C above +70°C) .......1.9W
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
(V
DD
= PV
DD
= CPV
DD
= 5V, GND = PGND = CPGND = 0V,
SHDN
= V
DD
, C
BIAS
= 1µF, C1 = C2 = 1µF, speaker load
terminated between OUT_+ and OUT_-, GAIN1 = GAIN2 = VOL = 0V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are
at T
A
= +25°C.) (Note 1)
PARAMETER
GENERAL
Supply Voltage Range
Quiescent Supply Current
Shutdown Supply Current
Bias Voltage
Switching Time
Input Resistance
Turn-On Time
Output Offset Voltage
Power-Supply Rejection Ratio
(Note 3)
V
DD
, PV
DD
I
DD
I
SHDN
V
BIAS
t
SW
R
IN
t
SON
V
OS
Measured between OUT_+ and OUT_-,
T
A
= +25°C
PV
DD
or V
DD
= 4.5V to 5.5V (T
A
= +25°C)
PSRR
f = 1kHz, V
RIPPLE
= 200mV
P-P
f = 10kHz, V
RIPPLE
= 200mV
P-P
Output Power (Note 4)
Total Harmonic Distortion Plus
Noise
P
OUT
THD+N = 1%,
f = 1kHz,
T
A
= +25°C
R
L
= 8Ω
R
L
= 4Ω
R
L
= 3Ω
0.65
1.2
75
Gain or input switching
Amplifier inputs (Note 2)
10
SHDN
= GND
1.7
Inferred from PSRR test
4.5
14
0.2
1.8
10
20
25
±0.4
90
80
55
0.8
1.5
2.2
0.01
0.02
%
W
dB
±6
30
5.5
29
5
1.9
V
mA
µA
V
µs
kΩ
ms
mV
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
THD+N
R
L
= 8Ω, P
OUT
= 500mW, f = 1kHz
R
L
= 4Ω, P
OUT
= 1W, f = 1kHz
2
_______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
= CPV
DD
= 5V, GND = PGND = CPGND = 0V,
SHDN
= V
DD
, C
BIAS
= 1µF, C1 = C2 = 1µF, speaker load
terminated between OUT_+ and OUT_-, GAIN1 = GAIN2 = VOL = 0V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are
at T
A
= +25°C.) (Note 1)
PARAMETER
Signal-to-Noise Ratio
Noise
Capacitive-Load Drive
Crosstalk
Slew Rate
SR
GAIN1 = 0, GAIN2 = 0
Gain (Maximum Volume Setting)
A
VMAX(SPKR)
GAIN1 = 1, GAIN2 = 0
GAIN1 = 0, GAIN2 = 1
GAIN1 = 1, GAIN2 = 1
CHARGE PUMP
Charge-Pump Frequency
VOLUME CONTROL
VOL Input Impedance
VOL Input Hysteresis
Full-Mute Input Voltage
Channel Matching
BEEP INPUT
Beep Signal Minimum Amplitude
Beep Signal Minimum Frequency
Logic Input High Voltage
Logic Input Low Voltage
Logic Input Current
V
BEEP
f
BEEP
V
IH
V
IL
I
IN
R
B
= 33kΩ (Note 6)
0.3
300
2
0.8
±1
V
P-P
Hz
V
V
µA
(Note 5)
A
V
= -25dB to +13.5dB
R
VOL
100
10
4.29
±0.2
MΩ
mV
V
dB
f
OSC
500
550
600
kHz
SYMBOL
SNR
V
n
C
L
CONDITIONS
R
L
= 8Ω, P
OUT
= 500mW, BW = 22Hz to
22kHz
BW = 22Hz to 22kHz, A-weighted
No sustained oscillations
L to R, R to L, f = 10kHz
MIN
TYP
90
80
200
75
1.4
6
7.5
9
10.5
dB
MAX
UNITS
dB
µV
RMS
pF
dB
V/µs
MAX9787
LOGIC INPUT (SHDN, GAIN1, GAIN2, VOL)
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
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 C
IN
.
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 R
B
dictates the minimum beep signal amplitude (see the
BEEP Input
section).
_______________________________________________________________________________________
3
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
MAX9787
Typical Operating Characteristics
(Measurement BW = 22Hz to 22kHz, T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX9787 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX9787 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
V
CC
= 5V
R
L
= 8Ω
A
V
= 10.5dB
OUTPUT POWER = 100mW
MAX9787 toc03
10
1
V
CC
= 5V
R
L
= 3Ω
A
V
= 10.5dB
OUTPUT POWER = 1.5W
10
1
V
CC
= 5V
R
L
= 4Ω
A
V
= 10.5dB
OUTPUT POWER = 1.25W
10
1
THD+N (%)
THD+N (%)
0.1
0.1
THD+N (%)
0.1
0.01
OUTPUT POWER = 500mW
0.001
0.01
OUTPUT POWER = 500mW
0.001
0.01
OUTPUT POWER = 600mW
0.001
0.0001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.0001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.0001
10
100
1k
FREQUENCY (Hz)
10k
100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9787 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9787 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
V
CC
= 5V
R
L
= 8Ω
A
V
= 10.5dB
MAX9787 toc06
100
V
CC
= 5V
R
L
= 3Ω
A
V
= 10.5dB
100
10
10
V
CC
= 5V
R
L
= 4Ω
A
V
= 10.5dB
100
10
THD+N (%)
THD+N (%)
1
f
IN
= 10kHz
0.1
THD+N (%)
1
f
IN
= 10kHz
0.1
1
0.1
f
IN
= 10kHz
0.01
f
IN
= 20Hz
0.001
0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT POWER (W)
f
IN
= 1kHz
0.01
f
IN
= 20Hz
0.001
0
0.5
1.0
1.5
OUTPUT POWER (W)
2.0
f
IN
= 1kHz
0.01
f
IN
= 20Hz
0.001
0
0.2
0.4
0.6
0.8
OUTPUT POWER (W)
1.0
1.2
f
IN
= 1kHz
OUTPUT POWER
vs. LOAD RESISTANCE
MAX9787 toc07
POWER DISSIPATION vs. OUTPUT POWER
MAX9787 toc08
3.0
2.5
OUTPUT POWER (W)
2.0
THD+N = 10%
1.5
1.0
0.5
0
1
10
LOAD RESISTANCE (Ω)
THD+N = 1%
V
CC
= 5V
f = 1kHz
A
V
= 10.5dB
5
V
DD
= 5V
f = 1kHz
P
OUT
= P
OUTL
+ P
OUTR
R
L
= 4Ω
POWER DISSIPATION (W)
4
3
2
R
L
= 8Ω
1
0
100
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
OUTPUT POWER (W)
4
_______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
MAX9787
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, T
A
= +25°C, unless otherwise noted.)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX9787 toc09
CROSSTALK vs. FREQUENCY
-10
-20
CROSSTALK (dB)
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
LEFT TO RIGHT
RIGHT TO LEFT
V
CC
= 5V
V
RIPPLE
= 200mV
P-P
R
L
= 4Ω
MAX9787 toc10
0
-10
-20
-30
PSRR (dB)
-40
-50
-60
-70
-80
-90
-100
10
V
RIPPLE
= 200mV
P-P
A
V
= 10.5dB
OUTPUT REFERRED
0
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
TURN-ON RESPONSE
MAX9787 toc11
TURN-OFF RESPONSE
MAX9787 toc12
5V/div
SHDN
OUT_+
AND
OUT_-
SHDN
OUT_+
AND
OUT_-
5V/div
2V/div
2V/div
OUT_+
- OUT_-
R
L
= 8Ω
20ms/div
100mV/div
OUT_+
- OUT_-
R
L
= 8Ω
20ms/div
20mV/div
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
16
SUPPLY CURRENT (mA)
14
12
10
8
6
4
2
0
4.50
4.75
5.00
5.25
5.50
SUPPLY VOLTAGE (V)
0.05
0
4.50
MAX9787 toc13
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9787 toc14
18
0.35
0.30
SUPPLY CURRENT (µA)
0.25
0.20
0.15
0.10
4.75
5.00
5.25
5.50
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
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