19-3049; Rev 2; 10/07
IT
TION K
VALUA
E
BLE
AVAILA
5V, Differential Input, DirectDrive, 130mW
Stereo Headphone Amplifiers with Shutdown
General Description
The MAX9722A/MAX9722B stereo headphone amplifiers
are designed for portable equipment where board space
is at a premium. The MAX9722A/MAX9722B use a
unique DirectDrive architecture to produce a ground-ref-
erenced output from a single supply, eliminating the
need for large DC-blocking capacitors, which saves
cost, board space, and component height. Additionally,
the gain of the amplifier is set internally
(-2V/V, MAX9722B) or adjusted externally (MAX9722A).
The MAX9722A/MAX9722B deliver up to 70mW per
channel into a 16Ω load or 130mW into a 32Ω load and
have low 0.009% THD+N. An 80dB at 217Hz power-sup-
ply rejection ratio (PSRR) allows these devices to operate
from noisy digital supplies without an additional linear
regulator. The MAX9722A/MAX9722B include ±8kV ESD
protection on the headphone outputs. Comprehensive
anticlick-and-pop circuitry suppresses audible clicks
and pops on startup and shutdown. A low-power shut-
down mode reduces the supply current to 0.1µA.
The MAX9722A/MAX9722B operate from a single 2.4V
to 5.5V supply, consume only 5.5mA of supply current,
feature short-circuit and thermal-overload protection,
and are specified over the extended -40°C to +85°C
temperature range. The devices are available in tiny
16-pin thin QFN (3mm
✕
3mm
✕
0.8mm) and 16-pin
TSSOP packages.
Features
♦
2.4V to 5.5V Single-Supply Operation
♦
High PSRR (80dB at 217Hz) Eliminates LDO
♦
No Bulky DC-Blocking Capacitors Required
♦
Ground-Referenced Outputs Eliminate DC Bias
Voltage on Headphone Ground Pin
♦
No Degradation of Low-Frequency Response Due
to Output Capacitors
♦
Differential Inputs for Enhanced Noise
Cancellation
♦
Adjustable Gain (MAX9722A) or Fixed -2V/V Gain
(MAX9722B)
♦
130mW per Channel into 32Ω
♦
Low 0.009% THD+N
♦
Integrated Click-and-Pop Suppression
♦
Low Quiescent Current (5.5mA)
♦
Short-Circuit and Thermal-Overload Protection
♦
±8kV ESD-Protected Amplifier Outputs (Human
Body Model)
♦
Available in a Space-Saving 16-Pin Thin QFN
(3mm
✕
3mm
✕
0.8mm) Package
MAX9722A/MAX9722B
Applications
Notebook and
Desktop PCs
MP3 Players
Flat-Panel Monitors
Cellular Phones
Smart Phones
PDAs
Portable Audio
Equipment
Simplified Diagram
Ordering Information
PART
MAX9722AETE
MAX9722AEUE
MAX9722BETE
MAX9722BEUE
PIN-PACKAGE
16 Thin QFN-EP* (3mm
✕
3mm
✕
0.8mm)
16 TSSOP
16 Thin QFN-EP* (3mm
✕
3mm
✕
0.8mm)
16 TSSOP
TOP
MARK
AAX
—
AAY
—
PKG
CODE
LEFT
AUDIO
INPUT
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS.
SHDN
T1633-5
U16-1
T1633-5
U16-1
RIGHT
AUDIO
INPUT
MAX9722B
FIXED GAIN ELIMINATES
EXTERNAL RESISTOR
NETWORK.
Note:
All devices are specified over the -40°C to +85°C operating
temperature range.
*EP
= Exposed paddle.
Pin Configurations and Typical Application Circuit appear at
end of data sheet.
1
________________________________________________________________
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.
5V, Differential Input, DirectDrive, 130mW
Stereo Headphone Amplifiers with Shutdown
MAX9722A/MAX9722B
ABSOLUTE MAXIMUM RATINGS
PGND to SGND .....................................................-0.3V to +0.3V
PV
DD
and SV
DD
to PGND or SGND .........................-0.3V to +6V
PV
SS
and SV
SS
to PGND..........................................+0.3V to -6V
IN_ to SGND ................................(SV
SS
- 0.3V) to (SV
DD
+ 0.3V)
OUT_ to PGND ......................................................-3.0V to +3.0V
SHDN
to SGND..........................(SGND - 0.3V) to (SV
DD
+ 0.3V)
C1P to PGND ...........................................-0.3V to (PV
DD
+ 0.3V)
C1N to PGND............................................(SV
SS
- 0.3V) to +0.3V
PV
DD
to SV
DD
...........................................................................0V
PV
SS
to SV
SS
............................................................................0V
Output Short Circuit to GND.......................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
16-Pin Thin QFN (derate 14.7mW/°C above +70°C)....1176mW
16-Pin TSSOP (derate 9.4mW/°C above +70°C) .........755mW
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
(PV
DD
= SV
DD
= +5V, PGND = SGND = 0V,
SHDN
= SV
DD
, C1 = C2 = 1µF, R
L
=
∞,
resistive load referenced to ground, for
MAX9722A gain = -1V/V (R
IN
= R
F
= 10kΩ), for MAX9722B gain = -2V/V (internally set), T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
GENERAL
Supply Voltage Range
Quiescent Supply Current
Shutdown Supply Current
SHDN
Input Logic High
SHDN
Input Logic Low
SHDN
Input Leakage Current
SHDN
to Full Operation Time
AMPLIFIERS
Voltage Gain
Gain Matching
Input Offset Voltage
Input Bias Current
Input Impedance
Input Common-Mode Voltage
Range
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
(Note 3)
Output Power
Output Voltage
Output Impedance in Shutdown
V
IS
I
BIAS
R
IN
V
CM
CMRR
PSRR
Input referred, MAX9722A, T
A
= +25°C
DC, V
DD
= 2.4V to 5.5V, input referred
f = 217Hz, 100mV
P-P
ripple, input referred
f = 10kHz, 100mV
P-P
ripple, input referred
P
OUT
V
OUT
R
L
= 16Ω, THD+N = 1%, T
A
= +25°C
R
L
= 32Ω, THD+N = 1%, T
A
= +25°C
R
L
= 1kΩ
60
A
V
MAX9722B (Note 2)
MAX9722B, between the right and left channels
Between IN_+ and IN_-, AC-coupled (MAX9722A)
Between IN_+ and IN_-, AC-coupled (MAX9722B)
IN_+ and IN_-
MAX9722B, measured at IN_
10
-0.5
-60
-80
-70
-90
-80
-50
70
130
2
10
mW
V
RMS
kΩ
dB
-1.98
-2
±2
±0.5
±1.5
50
14.4
20
+0.7
±2.5
±5
-2.02
V/V
%
mV
nA
kΩ
V
dB
t
SON
V
DD
I
DD
I
SHDN
V
IH
V
IL
-1
+0.05
80
Guaranteed by PSRR test
R
L
=
∞
SHDN
= SGND
2
0.8
+1
2.4
5.5
0.1
5.5
13
2
V
mA
µA
V
V
µA
µs
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
5V, Differential Input, DirectDrive, 130mW
Stereo Headphone Amplifiers with Shutdown
ELECTRICAL CHARACTERISTICS (continued)
(PV
DD
= SV
DD
= +5V, PGND = SGND = 0V,
SHDN
= SV
DD
, C1 = C2 = 1µF, R
L
=
∞,
resistive load referenced to ground, for
MAX9722A gain = -1V/V (R
IN
= R
F
= 10kΩ), for MAX9722B gain = -2V/V (internally set), T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
Total Harmonic Distortion Plus
Noise (Note 4)
Signal-to-Noise Ratio
Noise
Slew Rate
Maximum Capacitive Load
Charge-Pump Oscillator
Frequency
Crosstalk
ESD Protection
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
SYMBOL
THD+N
SNR
V
n
SR
C
L
f
OSC
R
L
= 32Ω, V
IN
= 200mV
P-P
, f = 10kHz, A
V
= 1
Human Body Model (OUTR and OUTL)
No sustained oscillation
505
CONDITIONS
R
L
= 16Ω, P
OUT
= 55mW, f = 1kHz
R
L
= 32Ω, P
OUT
= 125mW, f = 1kHz
R
L
= 32Ω, P
OUT
= 20mW, f = 22Hz to 22kHz
22Hz to 22kHz bandwidth, input AC grounded
MIN
TYP
0.03
0.009
100
6
0.5
200
600
78
±8
145
5
800
MAX
UNITS
%
dB
µV
RMS
V/µs
pF
kHz
dB
kV
°C
°C
MAX9722A/MAX9722B
Note 1:
Note 2:
Note 3:
Note 4:
All specifications are 100% tested at T
A
= +25°C; temperature limits are guaranteed by design.
Gain for the MAX9722A is adjustable.
The amplifier inputs are AC-coupled to ground through C
IN
_.
Measurement bandwidth is 22Hz to 22kHz.
Typical Operating Characteristics
(MAX9722A, PV
DD
= SV
DD
= +5V, PGND = SGND = 0V,
SHDN
= SV
DD
, C1 = C2 = 1µF, R
L
=
∞,
gain = -1V/V, single-ended input,
THD+N measurement bandwidth = 22Hz to 22kHz, T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9722 toc01
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9722 toc02
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
V
DD
= 5V
A
V
= -1V/V
R
L
= 16Ω
P
OUT
= 5mW
THD+N (%)
0.1
P
OUT
= 60mW
MAX9722 toc03
10
V
DD
= 3V
A
V
= -1V/V
R
L
= 16Ω
10
V
DD
= 3V
A
V
= -1V/V
R
L
= 32Ω
P
OUT
= 5mW
THD+N (%)
0.1
P
OUT
= 20mW
10
1
P
OUT
= 15mW
P
OUT
= 5mW
1
1
THD+N (%)
0.1
0.01
P
OUT
= 30mW
0.01
0.01
P
OUT
= 40mW
0.001
0.001
P
OUT
= 40mW
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
_______________________________________________________________________________________
3
5V, Differential Input, DirectDrive, 130mW
Stereo Headphone Amplifiers with Shutdown
MAX9722A/MAX9722B
Typical Operating Characteristics (continued)
(MAX9722A, PV
DD
= SV
DD
= +5V, PGND = SGND = 0V,
SHDN
= SV
DD
, C1 = C2 = 1µF, R
L
=
∞,
gain = -1V/V, single-ended input,
THD+N measurement bandwidth = 22Hz to 22kHz, T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9722 toc04
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9722 toc05
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
V
DD
= 5V
A
V
= -2V/V
R
L
= 32Ω
MAX9722 toc06
10
V
DD
= 5V
A
V
= -2V/V
R
L
= 16Ω
10
V
DD
= 5V
A
V
= -1V/V
R
L
= 32Ω
P
OUT
= 5mW
10
1
P
OUT
= 20mW
P
OUT
= 5mW
1
1
P
OUT
= 5mW
THD+N (%)
THD+N (%)
0.1
0.1
THD+N (%)
P
OUT
= 20mW
0.1
P
OUT
= 20mW
0.01
P
OUT
= 40mW
0.001
0.01
P
OUT
= 80mW
0.01
P
OUT
= 80mW
0.001
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
MAX9722 toc07
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9722 toc08
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9722 toc09
100
10
1
THD+N (%)
100
10
1
THD+N (%)
100
10
1
THD+N (%)
f = 1kHz
0.1
0.01
f = 10kHz
f = 1kHz
0.1
0.01
0.001
f = 20Hz
f = 10kHz
f = 10kHz
f = 1kHz
0.1
0.01
0.0001
0
10
20
30
40
50
OUTPUT POWER (mW)
V
DD
= 3V
A
V
= -1V/V
R
L
= 16Ω
60
70
0.001
0.0001
0
10
20
f = 20Hz
V
DD
= 3V
A
V
= -1V/V
R
L
= 32Ω
50
60
70
80
0.001
0.0001
0
10
f = 20Hz
V
DD
= 5V
A
V
= -1V/V
R
L
= 16Ω
40
50
60
70
30
40
20
30
OUTPUT POWER (mW)
OUTPUT POWER (mW)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
V
DD
= 5V
A
V
= -2V/V
R
L
= 16Ω
MAX9722 toc10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9722 toc11
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
V
DD
= 5V
A
V
= -2V/V
R
L
= 32Ω
f = 10kHz
f = 1kHz
MAX9722 toc12
100
10
1
THD+N (%)
0.1
0.01
0.001
0.0001
0
100
10
1
THD+N (%)
f = 10kHz
V
DD
= 5V
A
V
= -1V/V
R
L
= 32Ω
f = 10kHz
f = 1kHz
100
10
1
THD+N (%)
0.1
0.01
0.001
0.0001
f = 1kHz
0.1
0.01
f = 20Hz
0.001
0.0001
f = 20Hz
0
20
40
60
80
100
120
140
f = 20Hz
10
20
30
40
50
60
70
0
20
40
60
80
100
120
140
OUTPUT POWER (mW)
OUTPUT POWER (mW)
OUTPUT POWER (mW)
4
_______________________________________________________________________________________
5V, Differential Input, DirectDrive, 130mW
Stereo Headphone Amplifiers with Shutdown
MAX9722A/MAX9722B
Typical Operating Characteristics (continued)
(MAX9722A, PV
DD
= SV
DD
= +5V, PGND = SGND = 0V,
SHDN
= SV
DD
, C1 = C2 = 1µF, R
L
=
∞,
gain = -1V/V, single-ended input,
THD+N measurement bandwidth = 22Hz to 22kHz, T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9722 toc13
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. COMMON-MODE VOLTAGE
V
DD
= 5V
A
V
= -1V/V
f = 1kHz
DIFFERENTIAL
R
L
= 16Ω
MAX9722 toc14
OUTPUT POWER
vs. SUPPLY VOLTAGE
90
80
OUTPUT POWER (mW)
70
60
50
40
30
20
10
f = 1kHz
R
L
= 16Ω
2.4
2.6
2.8
3.0
3.2
3.4
3.6
THD+N = 1%
THD+N = 10%
MAX9722 toc15
100
10
1
THD+N (%)
0.1
0.01
0.001
0.0001
0
V
DD
= 5V
A
V
= -1V/V
R
L
= 16Ω
DIFFERENTIAL
100
10
1
THD+N (%)
0.1
0.01
100
f = 10kHz
f = 1kHz
R
L
= 32Ω
f = 20Hz
0.001
0.0001
10
20
30
40
50
60
70
-0.5
-0.3
-0.1
0.1
0.3
0.5
OUTPUT POWER (mW)
COMMON-MODE VOLTAGE (V)
0
SUPPLY VOLTAGE (V)
OUTPUT POWER
vs. SUPPLY VOLTAGE
MAX9722 toc16
OUTPUT POWER
vs. LOAD RESISTANCE
MAX9722 toc17
OUTPUT POWER
vs. LOAD RESISTANCE
180
160
OUTPUT POWER (mW)
140
120
100
80
60
40
20
0
THD+N = 1%
THD+N = 10%
V
DD
= 5V
f = 1kHz
A
V
= -1V/V
MAX9722 toc18
200
180
160
OUTPUT POWER (mW)
140
120
100
80
60
40
20
0
2.4
2.9
3.4
3.9
4.4
f = 1kHz
R
L
= 32Ω
THD+N = 1%
THD+N = 10%
100
90
80
OUTPUT POWER (mW)
70
60
50
40
30
20
10
0
THD+N = 1%
THD+N = 10%
V
DD
= 3V
f = 1kHz
A
V
= -1V/V
200
4.9
10
100
LOAD RESISTANCE (Ω)
1000
10
100
LOAD RESISTANCE (Ω)
1000
SUPPLY VOLTAGE (V)
POWER DISSIPATION
vs. OUTPUT POWER
MAX9722 toc19
POWER DISSIPATION
vs. OUTPUT POWER
MAX9722 toc20
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-10
-20
-30
V
DD
= 3V
A
V
= -1V/V
R
L
= 32Ω
MAX9722 toc21
300
250
POWER DISSIPATION (mW)
200
150
100
50
0
0
10
20
30
40
50
60
V
DD
= 3V
f = 1kHz
P
OUT
= P
L
+ P
R
R
L
= 16Ω
600
500
POWER DISSIPATION (mW)
400
V
DD
= 5V
f = 1kHz
P
OUT
= P
L
+ P
R
0
R
L
= 16Ω
300
200
100
0
R
L
= 32Ω
PSRR (dB)
-40
-50
-60
-70
-80
-90
-100
RIGHT
LEFT
R
L
= 32Ω
70
0
20
40
60
80
100
10
100
1k
FREQUENCY (Hz)
10k
100k
OUTPUT POWER (mW)
OUTPUT POWER (mW)
_______________________________________________________________________________________
5
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