General Description
The MAX9724A/MAX9724B stereo headphone ampli-
fiers are designed for portable equipment where board
space is at a premium. These devices use a unique
DirectDrive®architecture to produce a ground-refer-
enced output from a single supply, eliminating the need
for large DC-blocking capacitors, saving cost, board
space, and component height. The MAX9724 sup-
presses RF radiation received by input and supply
traces acting as antennas and prevents the amplifier
from demodulating the coupled noise. The MAX9724A
offers an externally adjustable gain while the
MAX9724B has an internally preset gain of -1.5V/V. The
MAX9724A/MAX9724B deliver up to 60mW per channel
into a 32Ωload and have low 0.02% THD+N. An 80dB
at 1kHz power-supply rejection ratio (PSRR) allows
these devices to operate from noisy digital supplies
without an additional linear regulator. Comprehensive
click-and-pop circuitry suppresses audible clicks and
pops on startup and shutdown.
The MAX9724A/MAX9724B operate from a single 2.7V
to 5.5V supply, consume only 3.5mA 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 12-
bump UCSP™ (1.5mm x 2mm) and 12-pin thin QFN
(3mm x 3mm x 0.8mm) packages.
Applications
Features
♦Improved RF Noise Rejection (Up to 67dB Over
Typical Amplifiers)
♦No Bulky DC-Blocking Capacitors Required
♦Low-Power Shutdown Mode, < 0.1μA
♦Adjustable Gain (MAX9724A) or Fixed -1.5V/V
Gain (MAX9724B)
♦Low 0.02% THD+N
♦High PSRR (80dB at 1kHz) Eliminates LDO
♦Integrated Click-and-Pop Suppression
♦2.7V to 5.5V Single-Supply Operation
♦Low Quiescent Current (3.5mA)
♦Available in Space-Saving Packages
12-Bump UCSP (1.5mm x 2mm)
12-Pin Thin QFN (3mm x 3mm x 0.8mm)
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-3597; Rev 6; 3/09
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.
EVALUATION KIT
AVAILABLE
PART GAIN
(V/V)
PIN-
PACKAGE
TOP
MARK
MAX9724AEBC+TG45
Adj. 12 UCSP
+ADH
MAX9724AETC+ Adj.
12 TQFN-EP*
+AAT
MAX9724BEBC+TG45
-1.5 12 UCSP +ADI
MAX9724BETC+ -1.5
12 TQFN-EP*
+AAU
Note: All devices specified over the -40°C to +85°C operating
range.
+
Denotes lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*
EP = Exposed paddle.
Cellular Phones
MP3 Players
Notebook PCs
Handheld Gaming Consoles
LEFT
AUDIO
INPUT
RIGHT
AUDIO
INPUT
SHDN
MAX9724A
LEFT
AUDIO
INPUT
RIGHT
AUDIO
INPUT
MAX9724B
SHDN
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
FIXED GAIN ELIMINATES
EXTERNAL RESISTOR
NETWORK
Block Diagrams
Pin Configurations appear at end of data sheet.
DVD Players
Smart Phones
PDAs
UCSP is a trademark of Maxim Integrated Products, Inc.
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
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.
VDD to GND..............................................................-0.3V to +6V
PVSS to SVSS .........................................................-0.3V to +0.3V
PGND to SGND .....................................................-0.3V to +0.3V
C1P to PGND..............................................-0.3V to (VDD + 0.3V)
C1N to PGND............................................(PVSS - 0.3V) to +0.3V
PVSS and SVSS to PGND..........................................-6V to +0.3V
IN_ to SGND (MAX9724A)..........................-0.3V to (VDD + 0.3V)
IN_ to SGND (MAX9724B) .............(SVSS - 0.3V) to (VDD + 0.3V)
OUT_ to SVSS (Note 1) ....-0.3V to Min (VDD - SVSS + 0.3V, +9V)
OUT_ to VDD (Note 2) ......+0.3V to Max (SVSS - VDD - 0.3V, -9V)
SHDN to _GND.........................................................-0.3V to +6V
OUT_ Short Circuit to GND ........................................Continuous
Short Circuit between OUTL and OUTR ....................Continuous
Continuous Input Current into PVSS..................................260mA
Continuous Input Current (any other pin) .........................±20mA
Continuous Power Dissipation (TA= +70°C, Multilayer board)
12-Bump UCSP (derate 6.5mW/°C above +70°C) ........519mW
θJA ................................................................................154 C/W
12-Pin TQFN (derate 16.7mW/°C above +70°C) .........1333mW
θJA..................................................................................60°C/W
θJC..................................................................................11°C/W
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Bump Temperature (soldering) Reflow............................+235°C
ELECTRICAL CHARACTERISTICS
(VDD = 5V, PGND = SGND, SHDN = 5V, C1 = C2 = 1µF, RL= ∞, resistive load reference to ground; for MAX9724A gain = -1.5V/V
(RIN = 20kΩ, RF= 30kΩ); for MAX9724B gain = -1.5V/V (internally set), TA= -40°C to +85°C, unless otherwise noted. Typical values
are at TA= +25°C, unless otherwise noted.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
GENERAL
Supply Voltage Range VDD Guaranteed by PSRR test 2.7 5.5 V
Quiescent Current ICC 3.5 5.5 mA
Shutdown Current ISHDN SHDN = SGND = PGND 0.1 1 µA
Shutdown to Full Operation tSON 180 µs
Input Impedance RIN MAX9724B, measured at IN_ 12 19 28 kΩ
Output Offset Voltage VOS (Note 4) ±1.5 ±10 mV
VDD = 2.7V to 5.5V, TA = +25°C 69 86
f = 1kHz, 100mVP-P (Note 4) 80Power-Supply Rejection Ratio PSRR
f = 20kHz, 100mVP-P (Note 4) 65
dB
RL = 32Ω, THD+N = 1% 30 63
Output Power (TQFN) POUT RL = 16Ω, THD+N = 1% 42 mW
RL = 32Ω, THD+N = 1% 25 45
Output Power (UCSP) POUT RL = 16Ω, THD+N = 1% 35 mW
Voltage Gain AVMAX9724B (Note 5) -1.52 -1.5 -1.48 V/V
Channel-to-Channel Gain Tracking MAX9724B ±0.15 %
RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz 0.003
RL = 32Ω, POUT = 50mW, fIN = 1kHz 0.02
Total Harmonic Distortion Plus
Noise (TQFN) (Note 6) THD+N
RL = 16Ω, POUT = 35mW, fIN = 1kHz 0.04
%
RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz 0.003
RL = 32Ω, POUT = 45mW, fIN = 1kHz 0.03
Total Harmonic Distortion Plus
Noise (UCSP) (Note 6) THD+N
RL = 16Ω, POUT = 32mW, fIN = 1kHz 0.05
%
BW = 22Hz to 22kHz 102
RL = 1kΩ,
VOUT = 2VRMS A-weighted 105
BW = 22Hz to 22kHz 98
Signal-to-Noise Ratio SNR RL = 32Ω,
POUT = 50mW A-weighted 101
dB
Note 1: OUTR and OUTL should be limited to no more than 9V above SVSS, or above VDD + 0.3V, whichever limits first.
Note 2: OUTR and OUTL should be limited to no more than 9V below VDD, or below SVSS - 0.3V, whichever limits first.
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 5V, PGND = SGND, SHDN = 5V, C1 = C2 = 1µF, RL= ∞, resistive load reference to ground; for MAX9724A gain = -1.5V/V
(RIN = 20kΩ, RF= 30kΩ); for MAX9724B gain = -1.5V/V (internally set), TA= -40°C to +85°C, unless otherwise noted. Typical values
are at TA= +25°C, unless otherwise noted.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Slew Rate SR 0.5 V/µs
Capacitive Drive CLNo sustained oscillations 100 pF
Crosstalk L to R, R to L, f = 10kHz, RL = 16Ω,
POUT = 15mW -70 dB
Charge-Pump Oscillator
Frequency fOSC 190 270 400 kHz
Into shutdown -67
Click-and-Pop Level KCP
RL = 32Ω, peak voltage,
A-weighted, 32 samples per
second (Notes 4, 7)
Out of
shutdown -64 dB
DIGITAL INPUTS (SHDN)
Input-Voltage High VINH (TQFN only) 2 V
Input-Voltage Low VINL (TQFN only) 0.8 V
Input-Voltage High VINH (UCSP only) 1.4 V
Input-Voltage Low VINL (UCSP only) 0.9 V
Input Leakage Current ±1 µA
ELECTRICAL CHARACTERISTICS
(VDD = 3V, PGND = SGND, SHDN = 3V, C1 = C2 = 1µF, RL= ∞, resistive load reference to ground; for MAX9724A gain = -1.5V/V
(RIN = 20kΩ, RF= 30kΩ); for MAX9724B gain = -1.5V/V (internally set), TA= -40°C to +85°C, unless otherwise noted. Typical values
are at TA= +25°C, unless otherwise noted.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Quiescent Current ICC 3.0 mA
Shutdown Current ISHDN SHDN = SGND = PGND 0.1 µA
f = 1kHz, 100mVP-P 80
Power-Supply Rejection Ratio
(Note 4) PSRR f = 20kHz, 100mVP-P 65 dB
RL = 32Ω, THD+N = 1% 20
Output Power (TQFN) POUT RL = 16Ω, THD+N = 1% 14 mW
RL = 32Ω, THD+N = 1% 17
Output Power (UCSP) POUT RL = 16Ω, THD+N = 1% 12 mW
RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz 0.05
RL = 32Ω, POUT = 15mW, fIN = 1kHz 0.03
Total Harmonic Distortion Plus
Noise (TQFN) (Note 6) THD+N
RL = 16Ω, POUT = 10mW, fIN = 1kHz 0.06
%
RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz 0.003
RL = 32Ω, POUT = 15mW, fIN = 1kHz 0.04
Total Harmonic Distortion Plus
Noise (UCSP) (Note 6) THD+N
RL = 16Ω, POUT = 10mW, fIN = 1kHz 0.06
%
Note 3: All specifications are 100% tested at TA= +25°C; temperature limits are guaranteed by design.
Note 4: The amplifier inputs are AC-coupled to GND.
Note 5: Gain for the MAX9724A is adjustable.
Note 6: Measurement bandwidth is 22Hz to 22kHz.
Note 7: Test performed with a 32Ωresistive load connected to GND. Mode transitions are controlled by SHDN. KCP level is calculated
as 20log[(peak voltage during mode transition, no input signal)/(peak voltage under normal operation at rated power level)].
Units are expressed in dB.
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL= ∞, gain = -1.5V/V (RIN = 20kΩ, RF= 30kΩfor the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA= +25°C, unless otherwise noted.)
100
010203040
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (TQFN)
MAX9724 toc01
OUTPUT POWER (mW)
THD+N (%)
VDD = 3V
RL = 16Ω
fIN = 1kHz
fIN = 20Hz
fIN = 10kHz
10
0 5 15 2510 20 30
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (UCSP)
MAX9724 toc02
OUTPUT POWER (mW)
THD+N (%)
VDD = 3V
RL = 16Ω
fIN = 1kHz
fIN = 20Hz
fIN = 10kHz
100
010 3020 40 50
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (TQFN)
MAX9724toc03
OUTPUT POWER (mW)
THD+N (%)
VDD = 3V
RL = 32Ω
fIN = 1kHz
fIN = 20Hz
fIN = 10kHz
10
05 1510 20 25 30 35 40
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (USCP)
MAX9724toc04
OUTPUT POWER (mW)
THD+N (%)
VDD = 3V
RL = 32Ω
fIN = 1kHz fIN = 10kHz
fIN = 20Hz
100
020 6040 80 100
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (TQFN)
MAX9724 toc05
OUTPUT POWER (mW)
THD+N (%)
VDD = 5V
RL = 16Ω
fIN = 1kHz
fIN = 20Hz
fIN = 10kHz
10
010 3020 40 50 60 70 80
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (UCSP)
MAX9724 toc06
OUTPUT POWER (mW)
THD+N (%)
VDD = 5V
RL = 16Ω
fIN = 1kHz
fIN = 20Hz
fIN = 10kHz
100
020 6040 80 120
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (TQFN)
MAX9724 toc07
OUTPUT POWER (mW)
THD+N (%)
100
VDD = 5V
RL = 32Ω
fIN = 1kHz
fIN = 20Hz
fIN = 10kHz
10
05025 75 100
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (UCSP)
MAX9724 toc08
OUTPUT POWER (mW)
THD+N (%)
VDD = 5V
RL = 32Ω
fIN = 1kHz
fIN = 20Hz
fIN = 10kHz
10 1k100 10k 100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (TQFN)
MAX9724 toc09
FREQUENCY (Hz)
THD+N (%)
1
0.1
0.001
0.01
VDD = 3V
RL = 16Ω
POUT = 5mW
POUT = 10mW
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
_______________________________________________________________________________________
5
Typical Operating Characteristics (continued)
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL= ∞, gain = -1.5V/V (RIN = 20kΩ, RF= 30kΩfor the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA= +25°C, unless otherwise noted.)
10 1k100 10k 100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (UCSP)
MAX9724 toc10
FREQUENCY (Hz)
THD+N (%)
1
0.1
0.001
0.01
VDD = 3V
RL = 16ΩPOUT = 5mW
POUT = 10mW
10 1k100 10k 100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (TQFN)
MAX9724 toc11
FREQUENCY (Hz)
THD+N (%)
1
0.1
0.001
0.01
VDD = 3V
RL = 32Ω
POUT = 8mW
POUT = 15mW
10 1k100 10k 100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (UCSP)
MAX9724 toc12
FREQUENCY (Hz)
THD+N (%)
1
0.1
0.001
0.01
VDD = 3V
RL = 32Ω
POUT = 8mW
POUT = 13mW
10 1k100 10k 100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (TQFN)
MAX9724 toc13
FREQUENCY (Hz)
THD+N (%)
1
0.1
0.001
0.01
VDD = 5V
RL = 16Ω
POUT = 20mW
POUT = 37mW
10 1k100 10k 100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (UCSP)
MAX9724 toc14
FREQUENCY (Hz)
THD+N (%)
1
0.1
0.001
0.01
VDD = 5V
RL = 16Ω
POUT = 20mW
POUT = 32mW
10 1k100 10k 100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (TQFN)
MAX9724 toc15
FREQUENCY (Hz)
THD+N (%)
1
0.1
0.001
0.01
VDD = 5V
RL = 32Ω
POUT = 50mW
POUT = 30mW
10 1k100 10k 100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (UCSP)
MAX9724 toc16
FREQUENCY (Hz)
THD+N (%)
1
0.1
0.001
0.01
VDD = 5V
RL = 32Ω
POUT = 45mW
POUT = 20mW
0
20
10
40
30
60
50
70
2.5 3.5 4.03.0 4.5 5.0 5.5
OUTPUT POWER
vs. SUPPLY VOLTAGE (TQFN)
MAX9724 toc17
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
fIN = 1kHz
RL = 16Ω
1% THD+N
10% THD+N
0
20
10
40
30
60
50
70
2.5 3.5 4.03.0 4.5 5.0 5.5
OUTPUT POWER
vs. SUPPLY VOLTAGE (UCSP)
MAX9724 toc18
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
fIN = 1kHz
RL = 16Ω
1% THD+N
10% THD+N
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL= ∞, gain = -1.5V/V (RIN = 20kΩ, RF= 30kΩfor the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA= +25°C, unless otherwise noted.)
0
40
20
80
60
100
120
2.5 3.5 4.03.0 4.5 5.0 5.5
OUTPUT POWER
vs. SUPPLY VOLTAGE (TQFN)
MAX9724 toc19
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
fIN = 1kHz
RL = 32Ω
1% THD+N
10% THD+N
0
40
20
80
60
100
120
2.5 3.5 4.03.0 4.5 5.0 5.5
OUTPUT POWER
vs. SUPPLY VOLTAGE (UCSP)
MAX9724 toc20
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
fIN = 1kHz
RL = 32Ω
1% THD+N
10% THD+N
35
0
10 100 1000
OUTPUT POWER
vs. LOAD RESISTANCE (TQFN)
5
MAX9724 toc21
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
15
10
20
25
30
VDD = 3V
fIN = 1kHz
1% THD+N
10% THD+N
35
0
10 100 1000
OUTPUT POWER
vs. LOAD RESISTANCE (UCSP)
5
MAX9724 toc22
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
15
10
20
25
30
VDD = 3V
fIN = 1kHz
THD+N = 1%
THD+N = 10%
100
0
10 100
OUTPUT POWER
vs. LOAD RESISTANCE (TQFN)
10
MAX9724 toc23
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
30
20
50
70
90
40
60
80
THD+N = 1%
VDD = 5V
fIN = 1kHz
THD+N = 10%
100
0
10 100
OUTPUT POWER
vs. LOAD RESISTANCE (UCSP)
10
MAX9724 toc24
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
30
20
50
70
90
40
60
80
THD+N = 1%
VDD = 5V
fIN = 1kHz
THD+N = 10%
0
50
150
100
200
250
POWER DISSIPATION
vs. OUTPUT POWER (TQFN)
MAX9724t oc25
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
04020 60 80
VDD = 3V
fIN = 1kHz
POUT = POUTL + POUTR
OUTPUTS IN PHASE
RL = 16Ω
RL = 32Ω
0
20
100
80
60
40
120
140
160
POWER DISSIPATION
vs. OUTPUT POWER (UCSP)
MAX9724t oc26
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
010152025305404535 50
VDD = 3V
fIN = 1kHz
POUT = POUTL + POUTR
OUTPUTS IN PHASE
RL = 16Ω
RL = 32Ω
0
-120
10 100 10k 100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-100
-80
-40
-60
-20
MAX9724 toc27
FREQUENCY (Hz)
PSRR (dB)
1k
VDD = 5V
VDD = 3V
RL = 32Ω
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
_______________________________________________________________________________________
7
0
-120
10 100 10k 100k
CROSSTALK vs. FREQUENCY
-100
-80
-40
-60
-20
MAX9724 toc28
FREQUENCY (Hz)
CROSSTALK (dB)
1k
RIGHT TO LEFT
LEFT TO RIGHT
POUT = 15mW
RL = 16Ω
20
40
30
60
50
70
80
0 100 15050
OUTPUT POWER vs. LOAD RESISTANCE AND
CHARGE-PUMP CAPACITOR SIZE (TQFN)
MAX9724 toc29
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
VDD = 5V
fIN = 1kHz
THD+N = 1%
C1 = C2 = 2.2μFC1 = C2 = 1μF
C1 = C2 = 0.47μF
0
40
30
20
10
60
50
70
80
0 100 15050
OUTPUT POWER vs. LOAD RESISTANCE AND
CHARGE-PUMP CAPACITOR SIZE (UCSP)
MAX9724 toc30
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
VDD = 5V
fIN = 1kHz
THD+N = 1%
C1 = C2 = 2.2μF
C1 = C2 = 1μF
C1 = C2 = 0.47μF
-140
-110
-130
-70
-90
-50
-120
-80
-100
-60
-40
0 5 10 15 20
OUTPUT SPECTRUM vs. FREQUENCY
MAX9724 toc31
FREQUENCY (kHz)
AMPLITUDE (dBV)
RL = 32Ω
VDD = 3V
fIN = 1kHz
VOUT = -60dBV
2.8
3.1
2.9
3.3
3.0
3.4
3.2
3.5
2.5 3.0 4.03.5 4.5 5.0 5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX9724 toc32
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
NO LOAD
INPUTS
GROUND
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE (TQFN)
MAX9724 toc33
SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT (nA)
5.04.54.03.53.0
20
40
60
80
100
120
140
0
2.5 5.5
NO LOAD INPUTS GND
Typical Operating Characteristics (continued)
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL= ∞, gain = -1.5V/V (RIN = 20kΩ, RF= 30kΩfor the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA= +25°C, unless otherwise noted.)
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
8 _______________________________________________________________________________________
Pin Description
PIN
TQFN UCSP NAME FUNCTION
1 C1 C1P Flying Capacitor Positive Terminal. Connect a 1µF ceramic capacitor from C1P to C1N.
2 C2 PGND Power Ground. Connect to SGND.
3 C3 C1N Flying Capacitor Negative Terminal. Connect a 1µF ceramic capacitor from C1P to C1N.
4C4PV
SS Charge-Pump Output. Connect to SVSS and bypass with a 1µF ceramic capacitor to PGND.
5A2SHDN Active-Low Shutdown Input
6 B3 INL Left-Channel Input
7 A1 SGND Signal Ground. Connect to PGND.
8 B2 INR Right-Channel Input
9B4SV
SS Amplifier Negative Supply. Connect to PVSS.
10 A3 OUTR Right-Channel Output
11 A4 OUTL Left-Channel Output
12 B1 VDD Positive Power-Supply Input. Bypass with a 1µF capacitor to PGND.
EP — EP Exposed Paddle. Internally connected to SVSS. Connect to SVSS or leave unconnected.
EXITING SHUTDOWN
MAX9724 toc34
VSHDN
5V/div
VOUT_
500mV/div
VIN_
1V/div
40μs/div
ENTERING SHUTDOWN
MAX9724 toc35
VSHDN
5V/div
VOUT_
500mV/div
VIN_
1V/div
20μs/div
Typical Operating Characteristics (continued)
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL= ∞, gain = -1.5V/V (RIN = 20kΩ, RF= 30kΩfor the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA= +25°C, unless otherwise noted.)
MAX9724A/MAX9724B
Detailed Description
The MAX9724A/MAX9724B stereo headphone ampli-
fiers feature Maxim’s DirectDrive architecture, eliminat-
ing the large output-coupling capacitors required by
conventional single-supply headphone amplifiers. The
device consists of two 60mW Class AB headphone
amplifiers, undervoltage lockout (UVLO)/shutdown con-
trol, charge pump, and comprehensive click-and-pop
suppression circuitry (see the
Functional
Diagram/Typical Operating Circuits
). The charge pump
inverts the positive supply (VDD), creating a negative
supply (PVSS). The headphone amplifiers operate from
these bipolar supplies with their outputs biased about
PGND (Figure 1). The benefit of this PGND bias is that
the amplifier outputs do not have a DC component. The
large DC-blocking capacitors required with convention-
al headphone amplifiers are unnecessary, conserving
board space, reducing system cost, and improving fre-
quency response. The MAX9724A/MAX9724B feature
an undervoltage lockout that prevents operation from
an insufficient power supply and click-and-pop sup-
pression that eliminates audible transients on startup
and shutdown. The MAX9724A/MAX9724B also feature
thermal-overload and short-circuit protection.
DirectDrive
Conventional single-supply headphone amplifiers have
their outputs biased about a nominal DC voltage (typi-
cally half the supply) for maximum dynamic range.
Large-coupling capacitors are needed to block this DC
bias from the headphone. Without these capacitors, a
significant amount of DC current flows to the head-
phone, resulting in unnecessary power dissipation and
possible damage to both headphone and headphone
amplifier.
Maxim’s DirectDrive architecture uses a charge pump
to create an internal negative supply voltage, allowing
the MAX9724A/MAX9724B outputs to be biased about
GND. With no DC component, there is no need for the
large DC-blocking capacitors. The MAX9724A/
MAX9724B charge pumps require two small ceramic
capacitors, conserving board space, reducing cost,
and improving the frequency response of the head-
phone amplifier. See the Output Power vs. Load
Resistance and Charge-Pump Capacitor Size graph in
the
Typical Operating Characteristics
for details of the
possible capacitor sizes. There is a low DC voltage on
the amplifier outputs due to amplifier offset. However,
the offsets of the MAX9724A/MAX9724B are typically
1.5mV, which, when combined with a 32Ωload, results
in less than 47µA of DC current flow to the head-
phones.
Charge Pump
The MAX9724A/MAX9724B feature a low-noise charge
pump. The 270kHz switching frequency is well beyond
the audio range and does not interfere with audio sig-
nals. The switch drivers feature a controlled switching
speed that minimizes noise generated by turn-on and
turn-off transients. The di/dt noise caused by the para-
sitic bond wire and trace inductance is minimized by
limiting the switching speed of the charge pump.
Although not typically required, additional high-fre-
quency noise attenuation can be achieved by increas-
ing the value of C2 (see the
Functional Diagram/Typical
Operating Circuits
).
RF Susceptibility
Modern audio systems are often subject to RF radiation
from sources like wireless networks and cellular phone
networks. Although the RF radiation is out of the audio
band, many signals, in particular GSM signals, contain
bursts or modulation at audible frequencies. Most ana-
log amplifiers demodulate the low-frequency envelope,
adding noise to the audio signal. The architecture of
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
_______________________________________________________________________________________ 9
VDD
-VDD
GND
VOUT
CONVENTIONAL DRIVER-BIASING SCHEME
DirectDrive BIASING SCHEME
VDD/2
VDD
VDD
GND
VOUT
2VDD
Figure 1. Conventional Driver Output Waveform vs.
MAX9724A/MAX9724B Output Waveform
MAX9724A/MAX9724B
the MAX9724 addresses the problem of the RF suscep-
tibility by rejecting RF noise and preventing it from cou-
pling into the audio band.
The RF susceptibility of an amplifier can be measured
by placing the amplifier in an isolated chamber and sub-
jecting it to an electric field of known strength. If the
electric field is modulated with an audio band signal, a
percentage of the modulated signal will be demodulat-
ed and amplified by the device in the chamber. Figure 2
shows the signal level at the outputs of an unoptimized
amplifier and the MAX9724. The test conditions are
shown in Table 1.
Click-and-Pop Suppression
In conventional single-supply audio amplifiers, the out-
put-coupling capacitor contributes significantly to audi-
ble clicks and pops. Upon startup, the amplifier charges
the coupling capacitor to its bias voltage, typically half
the supply. Likewise, on shutdown, the capacitor is dis-
charged. This results in a DC shift across the capacitor,
which appears as an audible transient at the speaker.
Since the MAX9724A/ MAX9724B do not require output-
coupling capacitors, this problem does not arise.
Additionally, the MAX9724A/MAX9724B feature exten-
sive click-and-pop suppression that eliminates any audi-
ble transient sources internal to the device.
Typically, the output of the device driving the
MAX9724A/MAX9724B has a DC bias of half the supply
voltage. At startup, the input-coupling capacitor, CIN, is
charged to the preamplifier’s DC bias voltage through
the MAX9724A/MAX9724B input resistor, RIN, and a
series 15kΩresistor. This DC shift across the capacitor
results in an audible click-and-pop. Delay the rise of
SHDN 4 to 5 time constants based on RIN x 15kΩx CIN
to eliminate clicks-and-pops caused by the input filter.
Shutdown
The MAX9724A/MAX9724B feature a < 0.1µA, low-
power shutdown mode that reduces quiescent current
consumption and extends battery life for portable appli-
cations. Drive SHDN low to disable the amplifiers and
the charge pump. In shutdown mode, the amplifier out-
put impedance is set to 14kΩ||RF(RFis 30kΩfor the
MAX9724B). The amplifiers and charge pump are
enabled once SHDN is driven high.
Applications Information
Power Dissipation
Under normal operating conditions, linear power ampli-
fiers can dissipate a significant amount of power. The
maximum power dissipation for each package is given
in the
Absolute Maximum Ratings
section under
Continuous Power Dissipation or can be calculated 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
PTT
DISSPKG MAX J MAX A
JA
() ()
=−
θ
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
10 ______________________________________________________________________________________
TEST PARAMETER SETTING
RF Field Strength 50V/m
RF Modulation Type Sine wave
RF Modulation Index 100%
RF Modulation Frequency 1kHz
Table 1. RF Susceptibility Test Conditions
MAX9724 fig02
RF CARRIER FREQUENCY (MHz)
AMPLIFIER OUTPUT AMPLITUDE (dBV)
1600 21001100
600
-80
-60
-40
-20
0
20
40
RF SUSCEPTIBLE
AMPLIFIER
MAX9724
62dB IMPROVEMENT
AT 850MHz 39dB IMPROVEMENT
AT 900MHz
67dB IMPROVEMENT
AT 1800MHz
49dB IMPROVEMENT
AT 1900MHz
-100
100 2600
Figure 2. RF Susceptibility of the MAX9724 and a Typical Headphone Amplifier
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
______________________________________________________________________________________ 11
°C/W as specified in the
Absolute Maximum Ratings
section. For example, θJA of the thin QFN package is
+68°C/W, and 154.2°C/W for the UCSP package.
The MAX9724A/MAX9724B have two power dissipation
sources; a charge pump and the two output amplifiers.
If power dissipation for a given application exceeds the
maximum allowed for a particular package, reduce
VDD, increase load impedance, decrease the ambient
temperature, or add heatsinking to the device. Large
output, supply, and ground traces decrease θJA, allow-
ing more heat to be transferred from the package to the
surrounding air.
Thermal-overload protection limits total power dissipa-
tion in the MAX9724A/MAX9724B. When the junction
temperature exceeds +150°C, the thermal protection
circuitry disables the amplifier output stage. The ampli-
fiers are enabled once the junction temperature cools
by approximately 12°C. This results in a pulsing output
under continuous thermal-overload conditions.
Output Dynamic Range
Dynamic range is the difference between the noise floor
of the system and the output level at 1% THD+N.
Determine the system’s dynamic range before setting the
maximum output gain. Output clipping occurs if the out-
put signal is greater than the dynamic range of the sys-
tem. The DirectDrive architecture of the MAX9724A/
MAX9724B has increased the dynamic range compared
to other single-supply amplifiers.
Maximum Output Swing
V
DD
< 4.35V
If the output load impedance is greater than 1kΩ, the
MAX9724A/MAX9724B can swing within a few millivolts
of their supply rail. For example, with a 3.3V supply, the
output swing is 2VRMS, or 2.83V peak while maintaining
a low 0.003% THD+N. If the supply voltage drops to
3V, the same 2.83V peak has only 0.05% THD+N.
V
DD
> 4.35V
Internal device structures limit the maximum voltage
swing of the MAX9724A/MAX9724B when operated at
supply voltages greater than 4.35V. The output must not
be driven such that the peak output voltage exceeds the
opposite supply voltage by 9V. For example, if VDD =
5V, the charge pump sets PVSS = -5V. Therefore, the
peak output swing must be less than ±4V to prevent
exceeding the absolute maximum ratings.
UVLO
The MAX9724A/MAX9724B feature an undervoltage
lockout (UVLO) function that prevents the device from
operating if the supply voltage is less than 2.7V. This fea-
ture ensures proper operation during brownout condi-
tions and prevents deep battery discharge. Once the
supply voltage exceeds the UVLO threshold, the
MAX9724A/MAX9724B charge pump is turned on and
the amplifiers are powered, provided that SHDN is high.
Component Selection
Input-Coupling Capacitor
The input capacitor (CIN), in conjunction with the input
resistor (RIN), forms a highpass filter that removes the
DC bias from an incoming signal (see the
Functional
Diagram/Typical Operating Circuits
). The AC-coupling
capacitor allows the device to bias the signal to an opti-
mum DC level. Assuming zero-source impedance, the -
3dB point of the highpass filter is given by:
Choose the CIN such that f-3dB is well below the lowest
frequency of interest. Setting f-3dB too high affects the
device’s low-frequency response. Use capacitors
whose dielectrics have low-voltage coefficients, such
as tantalum or aluminum electrolytic. Capacitors with
high-voltage coefficients, such as ceramics, can result
in increased distortion at low frequencies.
Charge-Pump Capacitor Selection
Use ceramic capacitors with a low ESR for optimum
performance. For optimal performance over the extend-
ed temperature range, select capacitors with an X7R
dielectric. Table 2 lists suggested manufacturers.
Flying Capacitor (C1)
The value of the flying capacitor (see the
Functional
Diagram/Typical Operating Circuits
) affects the charge
fRC
dB IN IN
−=
3
1
2π
SUPPLIER PHONE FAX WEBSITE
Taiyo Yuden 800-348-2496 847-925-0899 www.t-yuden.com
TDK 847-803-6100 847-390-4405 www.component.tdk.com
Murata 770-436-1300 770-436-3030 www.murata.com
Table 2. Suggested Capacitor Manufacturers
MAX9724A/MAX9724B
pump’s load regulation and output resistance. A C1
value that is too small degrades the device’s ability to
provide sufficient current drive, which leads to a loss of
output voltage. Increasing the value of C1 improves load
regulation and reduces the charge-pump output resis-
tance to an extent. See the Output Power vs. Load
Resistance and Charge-Pump Capacitor Size graph in
the
Typical Operating Characteristics
. Above 1µF, the
on-resistance of the switches and the ESR of C1 and C2
dominate.
Hold Capacitor (C2)
The hold capacitor value (see the
Functional
Diagram/Typical Operating Circuits
) and ESR directly
affect the ripple at PVSS. Increasing the value of C2
reduces output ripple. Likewise, decreasing the ESR of
C2 reduces both ripple and output resistance. Lower
capacitance values can be used in systems with low
maximum output power levels. See the Output Power
vs. Load Resistance and Charge-Pump Capacitor Size
graph in the
Typical Operating Characteristics
.
Power-Supply Bypass Capacitor (C3)
The power-supply bypass capacitor (see the
Functional
Diagram/Typical Operating Circuits
) lowers the output
impedance of the power supply, and reduces the
impact of the MAX9724A/MAX9724B’s charge-pump
switching transients. Bypass VDD with C3, the same
value as C1, and place it physically close to the VDD
and PGND pins.
Amplifier Gain
The gain of the MAX9724B amplifier is internally set to
-1.5V/V. All gain-setting resistors are integrated into the
device, reducing external component count. The inter-
nally set gain, in combination with DirectDrive, results in
a headphone amplifier that requires only five small
capacitors to complete the amplifier circuit: two for the
charge pump, two for audio input coupling, and one for
power-supply bypassing (see the
Functional
Diagram/Typical Operating Circuits
).
The gain of the MAX9724A amplifier is set externally as
shown in Figure 3, the gain is:
AV= -RF/RIN (V/V)
Choose feedback resistor values in the tens of kΩ
range. Lower values may cause excessive power dissi-
pation and require impractically small values of RIN for
large gain settings. The high-impedance state of the
outputs can also be degraded during shutdown mode
if an inadequate feedback resistor is used since the
equivalent output impedance during shutdown is
14kΩ||Rf(RFis equal to 30kΩfor the MAX9724B). The
source resistance of the input device may also need to
be taken into consideration. Since the effective value of
RIN is equal to the sum of the source resistance of the
input device and the value of the input resistor connect-
ed to the inverting terminal of the headphone amplifier
(20kΩfor the MAX9724B), the overall closed-loop gain
of the headphone amplifier can be reduced if the input
resistor is not significantly larger than the source resis-
tance of the input device.
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
12 ______________________________________________________________________________________
LEFT
AUDIO
INPUT
RIGHT
AUDIO
INPUT
OUTL
INL
INR
OUTR
MAX9724A
RIN
RIN
RF
RF
Figure 3. Gain Setting for the MAX9724A
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
______________________________________________________________________________________ 13
Lineout Amplifier and Filter Block
The MAX9724A can be used as an audio line driver
capable of providing 2VRMS into 10kΩloads with a sin-
gle 5V supply (see Figure 4 for the RMS Output Voltage
vs. Supply Voltage plot). 2VRMS is a popular audio line
level, first used in CD players, but now common in DVD
and set-top box (STB) interfacing standards. A 2VRMS
sinusoidal signal equates to approximately 5.7VP-P,
which means that the audio system designer cannot
simply run the lineout stage from a (typically common)
5V supply—the resulting output swing would be inade-
quate. A common solution to this problem is to use op
amps driven from split supplies (±5V typically), or to
use a high-voltage supply rail (9V to 12V). This can
mean adding extra cost and complexity to the system
power supply to meet this output level requirement.
Having the ability to derive 2VRMS from a 5V supply, or
even 3.3V supply, can often simplify power-supply
design in some systems.
When the MAX9724A is used as a line driver to provide
outputs that feed stereo equipment (receivers, STBs,
notebooks, and desktops) with a digital-to-analog con-
verter (DAC) used as an audio input source, it is often
desirable to eliminate any high-frequency quantization
noise produced by the DAC output before it reaches
the load. This high-frequency noise can cause the input
stages of the line-in equipment to exceed slew-rate lim-
itations or create excessive EMI emissions on the
cables between devices.
LEFT
AUDIO
INPUT
RIGHT
AUDIO
INPUT
OUTL
INL
INR
OUTR
MAX9724A
7.5kΩ 7.5kΩ
7.5kΩ 7.5kΩ
15kΩ
10kΩ
10kΩ
15kΩ
1.2nF
1.2nF
220pF
220pF
LINE IN DEVICE
STEREO
DAC
1μF
1μF
Figure 5. MAX9724A Line Out Amplifier and Filter Block Configuration
RMS OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
RMS OUTPUT VOLTAGE (V)
5.04.54.03.53.0
2.0
2.5
3.0
3.5
1.5
2.5 5.5
RL = 10kΩ
1% THD+N
fIN = 1kHz
RL = 1kΩ
1% THD+N
LIMITED BY
ABS. MAXIMUM
RATINGS
Figure 4. RMS Output Voltage vs. Supply Voltage
To suppress this noise, and to provide a 2VRMS stan-
dard audio output level from a single 5V supply, the
MAX9724A can be configured as a line driver and
active lowpass filter. Figure 5 shows the MAX9724A
connected as 2-pole Rauch/multiple feedback filter with
a passband gain of 6dB and a -3dB (below passband)
cutoff frequency of approximately 27kHz (see Figure 6
for the Gain vs. Frequency plot).
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Connect PGND and SGND together at a
single point on the PC Board. Connect PVSS to SVSS
and bypass with a 1µF capacitor. Place the power-sup-
ply bypass capacitor and the charge-pump hold
capacitor as close to the MAX9724 as possible. Route
PGND and all traces that carry switching transients
away from SGND and the audio signal path. The thin
QFN package features an exposed paddle that
improves thermal efficiency. Ensure that the exposed
paddle is electrically isolated from PGND, SGND,
and VDD. Connect the exposed paddle to SVSS only
when the board layout dictates that the exposed
paddle cannot be left floating.
UCSP Applications Information
For the latest application details on UCSP construction,
dimensions, tape carrier information, printed circuit
board techniques, bump-pad layout, and recommend-
ed reflow temperature profile, as well as the latest infor-
mation on reliability testing results, refer to the
Application Note
UCSP—A Wafer-Level Chip-Scale
Package
available on Maxim’s website at www.maxim-
ic.com/ucsp.
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
14 ______________________________________________________________________________________
MAX9724A ACTIVE FILTER GAIN
vs. FREQUENCY
FREQUENCY (Hz)
GAIN (dB)
100k10k
-30
-25
-20
-15
-10
-5
0
5
10
-35
1k 1M
RL = 10kΩ
Figure 6. Frequency Response of Active Filter of Figure 4
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
______________________________________________________________________________________ 15
MAX9710
OUTR+
OUTR-
OUTL-
OUTL+
INR
INL
BIAS
PVDD
VDD
SHDN
15kΩ
15kΩ
15kΩ
15kΩ
VDD
0.1μF
1μF
0.1μF
1μF
MAX9724B
0.1μF
OUTL
OUTR
SGND
C1P C1N
PGND
PVSS
SVSS VDD
SHDN
1μF
O.47μF
O.47μF
INL
INR
μCONTROLLER
STEREO
DAC
1μF
100kΩ
100kΩ
VDD
1μF
VDD
MUTE
PGND GND
System Diagram
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
16 ______________________________________________________________________________________
CHARGE
PUMP
UVLO/
SHUTDOWN
CONTROL
CLICK-AND-POP
SUPPRESSION
C1N
C1P
PVSS SVSS PGND SGND
*RIN AND RF VALUES ARE CHOSEN FOR A GAIN -1.5V/V.
( ) UCSP PACKAGE
INR
VDD SHDN
ON
OFF
SVSS
VDD
SGND
INL
RF*
30kΩ
RIN*
20kΩ
RIN*
20kΩ
OUTR
LEFT
AUDIO
INPUT
RIGHT
AUDIO
INPUT
HEADPHONE
JACK
5
(A2)
12
(B1)
1
(C1)
2
(C2)
3
(C3)
4
(C4)
9
(B4)
11
(A4)
6
(B3)
10
(A3)
7
(A1)
C1
1μF
C2
1μF
2.7V TO 5.5V
C3
1μF
CIN
0.47μF
SVSS
VDD
OUTL
CIN
0.47μF
8
(B2)
RF*
30kΩ
MAX9724A
Functional Diagram/Typical Operating Circuits
MAX9724A/MAX9724B
CHARGE
PUMP
UVLO/
SHUTDOWN
CONTROL
CLICK-AND-POP
SUPPRESSION
C1N
C1P
PVSS SVSS PGND SGND
( ) UCSP PACKAGE
INR
VDD SHDN
SVSS
VDD
SGND
INL
RF
30kΩ
RIN
20kΩ
RIN*
20kΩ
OUTR
LEFT
AUDIO
INPUT
RIGHT
AUDIO
INPUT
HEADPHONE
JACK
5
(A2)
12
(B1)
1
(C1)
2
(C2)
3
(C3)
4
(C4)
9
(B4)
11
(A4)
6
(B3)
10
(A3)
7
(A1)
C1
1μF
C2
1μF
2.7V TO 5.5V
C3
1μF
CIN
0.47μF
VSS
VDD
OUTL
CIN
0.47μF
8
(B2)
RF*
30kΩ
MAX9724B
ON
OFF
Functional Diagram/Typical Operating Circuits (continued)
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
______________________________________________________________________________________ 17
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
18 ______________________________________________________________________________________
TOP VIEW
12
11
10
4
5
6
1
+
23
987
MAX9724A
MAX9724B
TQFN
C1P
PGND
C1N
PVSS
SHDN
INL
SGND
INR
SVSS
OUTR
OUTL
VDD
Pin Configurations
UCSP
TOP VIEW (BUMPS ON BOTTOM)
MAX9724A/MAX9724B
1234
SGND SHDN OUTR OUTL
VDD INR INL SVSS
C1P PGND C1N PVSS
B
A
C
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.
12 UCSP B12-1 21-0104
12 TQFN T1233-1 21-0136
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________
19
© 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 5/05 Initial release —
1 1/06 Added RF immunity to General Description, Features, and Detailed
Description.1, 7
2 11/06 Added UCSP package. 1–3, 6, 9, 12, 14–16
3 3/07 Updated Electrical Characteristics table and Typical Operating
Characteristics.1–6, 17, 18
4 6/07 Corrected Pin Description, Pin Configuration, and Functional
Diagrams/Typical Operating Circuits with new UCSP information. 1–6, 12, 14–16
5 3/08 Updated Absolute Maximum Ratings and Click-and-Pop Suppression
section. 2, 10
6 3/09 Updated Ordering Information, style changes 1, 10, 18, 19
