19-3597; Rev 6; 3/09
KIT
ATION
EVALU
E
L
B
AVAILA
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
The MAX9724A/MAX9724B stereo headphone amplifiers are designed for portable equipment where board
space is at a premium. These devices use a unique
DirectDrive® architecture to produce a ground-referenced output from a single supply, eliminating the need
for large DC-blocking capacitors, saving cost, board
space, and component height. The MAX9724 suppresses 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 32Ω load 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 12bump UCSP™ (1.5mm x 2mm) and 12-pin thin QFN
(3mm x 3mm x 0.8mm) packages.
Applications
Cellular Phones
MP3 Players
Notebook PCs
Handheld Gaming Consoles
DVD Players
Smart Phones
PDAs
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
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)
Ordering Information
PART
GAIN
(V/V)
PINPACKAGE
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.
Pin Configurations appear at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
Block Diagrams
MAX9724B
MAX9724A
LEFT
AUDIO
INPUT
SHDN
RIGHT
AUDIO
INPUT
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
LEFT
AUDIO
INPUT
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
SHDN
RIGHT
AUDIO
INPUT
FIXED GAIN ELIMINATES
EXTERNAL RESISTOR
NETWORK
________________________________________________________________ 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
MAX9724A/MAX9724B
General Description
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
ABSOLUTE MAXIMUM RATINGS
VDD to GND ..............................................................-0.3V to +6V
Continuous Input Current into PVSS ..................................260mA
PVSS to SVSS .........................................................-0.3V to +0.3V
Continuous Input Current (any other pin) .........................±20mA
PGND to SGND .....................................................-0.3V to +0.3V
Continuous Power Dissipation (TA = +70°C, Multilayer board)
12-Bump UCSP (derate 6.5mW/°C above +70°C) ........519mW
C1P to PGND..............................................-0.3V to (VDD + 0.3V)
C1N to PGND............................................(PVSS - 0.3V) to +0.3V
θJA ................................................................................154 C/W
PVSS and SVSS to PGND..........................................-6V to +0.3V
12-Pin TQFN (derate 16.7mW/°C above +70°C) .........1333mW
IN_ to SGND (MAX9724A)..........................-0.3V to (VDD + 0.3V)
θJA ..................................................................................60°C/W
IN_ to SGND (MAX9724B) .............(SVSS - 0.3V) to (VDD + 0.3V)
θJC ..................................................................................11°C/W
OUT_ to SVSS (Note 1) ....-0.3V to Min (VDD - SVSS + 0.3V, +9V)
Operating Temperature Range ...........................-40°C to +85°C
OUT_ to VDD (Note 2) ......+0.3V to Max (SVSS - VDD - 0.3V, -9V)
Storage Temperature Range .............................-65°C to +150°C
SHDN to _GND.........................................................-0.3V to +6V
Junction Temperature ......................................................+150°C
OUT_ Short Circuit to GND ........................................Continuous
Lead Temperature (soldering, 10s) .................................+300°C
Short Circuit between OUTL and OUTR ....................Continuous
Bump Temperature (soldering) Reflow............................+235°C
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.
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 = 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
GENERAL
SYMBOL
Supply Voltage Range
VDD
Quiescent Current
ICC
Shutdown Current
Shutdown to Full Operation
ISHDN
tSON
CONDITIONS
Guaranteed by PSRR test
RIN
MAX9724B, measured at IN_
Output Offset Voltage
VOS
(Note 4)
PSRR
VDD = 2.7V to 5.5V, TA = +25°C
f = 1kHz, 100mVP-P (Note 4)
12
69
f = 20kHz, 100mVP-P (Note 4)
Output Power (TQFN)
POUT
Output Power (UCSP)
POUT
Voltage Gain
AV
Channel-to-Channel Gain Tracking
Total Harmonic Distortion Plus
Noise (TQFN) (Note 6)
THD+N
Total Harmonic Distortion Plus
Noise (UCSP) (Note 6)
THD+N
Signal-to-Noise Ratio
2
SNR
RL = 32Ω, THD+N = 1%
RL = 16Ω, THD+N = 1%
RL = 32Ω, THD+N = 1%
MAX
UNITS
5.5
V
3.5
5.5
mA
0.1
180
1
µA
µs
19
28
kΩ
±1.5
±10
mV
86
80
dB
65
30
63
25
42
45
RL = 16Ω, THD+N = 1%
MAX9724B (Note 5)
TYP
2.7
SHDN = SGND = PGND
Input Impedance
Power-Supply Rejection Ratio
MIN
mW
mW
35
-1.52
-1.5
MAX9724B
±0.15
RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz
0.003
RL = 32Ω, POUT = 50mW, fIN = 1kHz
0.02
RL = 16Ω, POUT = 35mW, fIN = 1kHz
RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz
0.04
0.003
RL = 32Ω, POUT = 45mW, fIN = 1kHz
0.03
RL = 16Ω, POUT = 32mW, fIN = 1kHz
0.05
RL = 1kΩ,
VOUT = 2VRMS
BW = 22Hz to 22kHz
A-weighted
102
105
RL = 32Ω,
POUT = 50mW
BW = 22Hz to 22kHz
98
A-weighted
101
_______________________________________________________________________________________
-1.48
V/V
%
%
%
dB
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
(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
Slew Rate
SR
Capacitive Drive
CL
Crosstalk
CONDITIONS
MIN
TYP
MAX
UNITS
0.5
V/µs
No sustained oscillations
100
pF
L to R, R to L, f = 10kHz, RL = 16Ω,
POUT = 15mW
-70
dB
Charge-Pump Oscillator
Frequency
fOSC
Click-and-Pop Level
KCP
Into shutdown
RL = 32Ω, peak voltage,
A-weighted, 32 samples per Out of
second (Notes 4, 7)
shutdown
VINH
VINL
VINH
VINL
(TQFN only)
(TQFN only)
(UCSP only)
(UCSP only)
190
270
400
kHz
-67
dB
-64
DIGITAL INPUTS (SHDN)
Input-Voltage High
Input-Voltage Low
Input-Voltage High
Input-Voltage Low
Input Leakage Current
2
0.8
1.4
0.9
±1
V
V
V
V
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
Quiescent Current
ICC
Shutdown Current
ISHDN
Power-Supply Rejection Ratio
(Note 4)
PSRR
Output Power (TQFN)
POUT
Output Power (UCSP)
POUT
Total Harmonic Distortion Plus
Noise (TQFN) (Note 6)
Total Harmonic Distortion Plus
Noise (UCSP) (Note 6)
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
THD+N
THD+N
CONDITIONS
MIN
TYP
MAX
UNITS
3.0
mA
SHDN = SGND = PGND
0.1
µA
f = 1kHz, 100mVP-P
80
f = 20kHz, 100mVP-P
65
RL = 32Ω, THD+N = 1%
20
RL = 16Ω, THD+N = 1%
14
RL = 32Ω, THD+N = 1%
17
RL = 16Ω, THD+N = 1%
12
RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz
0.05
RL = 32Ω, POUT = 15mW, fIN = 1kHz
0.03
RL = 16Ω, POUT = 10mW, fIN = 1kHz
0.06
RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz
0.003
RL = 32Ω, POUT = 15mW, fIN = 1kHz
0.04
RL = 16Ω, POUT = 10mW, fIN = 1kHz
0.06
dB
mW
mW
%
%
All specifications are 100% tested at TA = +25°C; temperature limits are guaranteed by design.
The amplifier inputs are AC-coupled to GND.
Gain for the MAX9724A is adjustable.
Measurement bandwidth is 22Hz to 22kHz.
Test performed with a 32Ω resistive 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.
_______________________________________________________________________________________
3
MAX9724A/MAX9724B
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (TQFN)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (UCSP)
VDD = 3V
RL = 16Ω
10
100
MAX9724 toc02
10
MAX9724 toc01
100
VDD = 3V
RL = 16Ω
MAX9724toc03
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (TQFN)
VDD = 3V
RL = 32Ω
10
1
fIN = 1kHz
0.1
THD+N (%)
THD+N (%)
0.1
fIN = 1kHz
0.1
fIN = 10kHz
fIN = 10kHz
0.01
fIN = 10kHz
fIN = 1kHz
0.01
0.01
fIN = 20Hz
0
10
20
30
40
0
5
10
15
20
25
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (USCP)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (TQFN)
20
30
40
50
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (UCSP)
10
MAX9724 toc05
MAX9724toc04
100
VDD = 5V
RL = 16Ω
10
1
10
OUTPUT POWER (mW)
OUTPUT POWER (mW)
VDD = 3V
RL = 32Ω
0
30
OUTPUT POWER (mW)
10
fIN = 20Hz
0.001
0.001
0.001
MAX9724 toc06
fIN = 20Hz
VDD = 5V
RL = 16Ω
0.1
THD+N (%)
1
THD+N (%)
THD+N (%)
1
1
fIN = 1kHz
0.1
fIN = 10kHz
0.01
fIN = 10kHz
fIN = 1kHz
fIN = 1kHz
0.1
fIN = 10kHz
0.01
0.01
fIN = 20Hz
fIN = 20Hz
0.001
5
10
15
20
25
30
35
40
0.001
0
20
40
60
80
100
OUTPUT POWER (mW)
OUTPUT POWER (mW)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (TQFN)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (UCSP)
VDD = 5V
RL = 32Ω
10
10
20
30
40
50
60
70
80
OUTPUT POWER (mW)
10
MAX9724 toc07
100
0
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (TQFN)
1
MAX9724 toc08
0
fIN = 20Hz
0.001
VDD = 5V
RL = 32Ω
MAX9724 toc09
THD+N (%)
1
VDD = 3V
RL = 16Ω
1
1
fIN = 1kHz
0.1
POUT = 5mW
THD+N (%)
THD+N (%)
0.1
THD+N (%)
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
fIN = 1kHz
0.1
0.01
0.01
0.01
fIN = 10kHz
fIN = 20Hz
fIN = 20Hz
0.001
0.001
0
20
40
60
80
OUTPUT POWER (mW)
4
POUT = 10mW
fIN = 10kHz
100
120
0.001
0
25
50
OUTPUT POWER (mW)
75
100
10
100
1k
FREQUENCY (Hz)
_______________________________________________________________________________________
10k
100k
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
POUT = 5mW
VDD = 3V
RL = 32Ω
1
VDD = 3V
RL = 32Ω
0.1
THD+N (%)
THD+N (%)
POUT = 10mW
THD+N (%)
0.1
0.1
POUT = 8mW
POUT = 8mW
0.01
0.01
0.01
MAX9724 toc12
1
MAX9724 toc11
VDD = 3V
RL = 16Ω
MAX9724 toc10
1
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (UCSP)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (TQFN)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (UCSP)
POUT = 13mW
POUT = 15mW
0.001
0.001
0.001
100
1k
10k
10
100k
100
10k
10
100k
POUT = 20mW
VDD = 5V
RL = 16Ω
VDD = 5V
RL = 32Ω
0.1
POUT = 30mW
THD+N (%)
POUT = 20mW
THD+N (%)
THD+N (%)
POUT = 37mW
0.01
0.01
POUT = 32mW
POUT = 50mW
0.001
0.001
0.001
1k
10k
10
100k
100
POUT = 20mW
0.01
50
10% THD+N
40
30
20
10
FREQUENCY (Hz)
fIN = 1kHz
RL = 16Ω
60
10k
100k
100k
50
10% THD+N
40
30
20
1% THD+N
10
0
0.001
10k
70
1% THD+N
POUT = 45mW
1k
1k
OUTPUT POWER
vs. SUPPLY VOLTAGE (UCSP)
MAX9724 toc17
fIN = 1kHz
RL = 16Ω
60
OUTPUT POWER (mW)
VDD = 5V
RL = 32Ω
100
100
FREQUENCY (Hz)
70
MAX9724 toc16
1
10
10
100k
OUTPUT POWER
vs. SUPPLY VOLTAGE (TQFN)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (UCSP)
THD+N (%)
10k
FREQUENCY (Hz)
FREQUENCY (Hz)
0.1
1k
MAX9724 toc18
100
OUTPUT POWER (mW)
10
100k
1
0.1
0.1
10k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (TQFN)
MAX9724 toc14
1
MAX9724 toc13
VDD = 5V
RL = 16Ω
1k
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (UCSP)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (TQFN)
0.01
100
FREQUENCY (Hz)
FREQUENCY (Hz)
1
1k
MAX9724 toc15
10
0
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
MAX9724A/MAX9724B
Typical Operating Characteristics (continued)
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.)
40
20
0
10% THD+N
60
40
1% THD+N
3.0
3.5
4.0
4.5
5.0
5.5
1% THD+N
10
0
2.5
3.0
3.5
4.0
4.5
5.0
10
5.5
100
1000
OUTPUT POWER
vs. LOAD RESISTANCE (UCSP)
OUTPUT POWER
vs. LOAD RESISTANCE (TQFN)
OUTPUT POWER
vs. LOAD RESISTANCE (UCSP)
THD+N = 1%
60
50
40
THD+N = 1%
30
80
VDD = 5V
fIN = 1kHz
10
100
1000
60
50
40
THD+N = 1%
30
VDD = 5V
fIN = 1kHz
10
0
0
10
70
20
20
0
THD+N = 10%
90
OUTPUT POWER (mW)
15
70
MAX9724 toc24
80
OUTPUT POWER (mW)
20
THD+N = 10%
90
100
MAX9724 toc23
100
MAX9724 toc22
VDD = 3V
fIN = 1kHz
5
10
10
100
100
LOAD RESISTANCE (Ω)
LOAD RESISTANCE (Ω)
LOAD RESISTANCE (Ω)
POWER DISSIPATION
vs. OUTPUT POWER (TQFN)
POWER DISSIPATION
vs. OUTPUT POWER (UCSP)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
RL = 16Ω
150
RL = 32Ω
100
VDD = 3V
fIN = 1kHz
POUT = POUTL + POUTR
OUTPUTS IN PHASE
50
120
-40
100
80
60
40
OUTPUT POWER (mW)
60
80
-60
VDD = 5V
-80
VDD = 3V
fIN = 1kHz
POUT = POUTL + POUTR
OUTPUTS IN PHASE
40
-100
0
20
RL = 32Ω
-20
RL = 32Ω
20
0
MAX9724 toc27
RL = 16Ω
PSRR (dB)
POWER DISSIPATION (mW)
200
140
0
MAX9724t oc26
160
MAX9724t oc25
250
6
15
LOAD RESISTANCE (Ω)
25
0
20
SUPPLY VOLTAGE (V)
THD+N = 10%
10
25
SUPPLY VOLTAGE (V)
35
30
VDD = 3V
fIN = 1kHz
10% THD+N
5
0
2.5
OUTPUT POWER (mW)
80
20
1% THD+N
30
OUTPUT POWER (mW)
10% THD+N
60
fIN = 1kHz
RL = 32Ω
100
OUTPUT POWER (mW)
80
35
MAX9724 toc20
fIN = 1kHz
RL = 32Ω
100
OUTPUT POWER (mW)
120
MAX9724 toc19
120
OUTPUT POWER
vs. LOAD RESISTANCE (TQFN)
OUTPUT POWER
vs. SUPPLY VOLTAGE (UCSP)
MAX9724 toc21
OUTPUT POWER
vs. SUPPLY VOLTAGE (TQFN)
POWER DISSIPATION (mW)
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
VDD = 3V
-120
0
5
10 15 20 25 30 35 40 45
OUTPUT POWER (mW)
50
10
100
1k
FREQUENCY (Hz)
_______________________________________________________________________________________
10k
100k
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
OUTPUT POWER vs. LOAD RESISTANCE AND
CHARGE-PUMP CAPACITOR SIZE (TQFN)
CROSSTALK vs. FREQUENCY
RIGHT TO LEFT
-80
LEFT TO RIGHT
-100
50
C1 = C2 = 0.47μF
40
VDD = 5V
fIN = 1kHz
THD+N = 1%
20
1k
100
10k
0
100k
50
OUTPUT POWER vs. LOAD RESISTANCE AND
CHARGE-PUMP CAPACITOR SIZE (UCSP)
C1 = C2 = 2.2μF
OUTPUT SPECTRUM vs. FREQUENCY
-60
AMPLITUDE (dBV)
C1 = C2 = 1μF
40
C1 = C2 = 0.47μF
30
RL = 32Ω
VDD = 3V
fIN = 1kHz
VOUT = -60dBV
-50
60
50
150
-40
MAX9724 toc30
80
70
100
LOAD RESISTANCE (Ω)
FREQUENCY (Hz)
-70
MAX9724 toc31
10
OUTPUT POWER (mW)
MAX9724 toc29
60
30
-120
-80
-90
-100
-110
20
-120
VDD = 5V
fIN = 1kHz
THD+N = 1%
10
-130
0
-140
0
50
100
150
0
5
10
15
20
LOAD RESISTANCE (Ω)
FREQUENCY (kHz)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE (TQFN)
140
MAX9724 toc32
3.5
NO LOAD INPUTS GND
120
SHUTDOWN CURRENT (nA)
3.4
SUPPLY CURRENT (mA)
C1 = C2 = 1μF
3.3
3.2
3.1
3.0
NO LOAD
INPUTS
GROUND
2.9
MAX9724 toc33
CROSSTALK (dB)
-40
-60
C1 = C2 = 2.2μF
70
OUTPUT POWER (mW)
POUT = 15mW
RL = 16Ω
-20
80
MAX9724 toc28
0
100
80
60
40
20
0
2.8
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
7
MAX9724A/MAX9724B
Typical Operating Characteristics (continued)
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A),
THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.)
EXITING SHUTDOWN
VSHDN
5V/div
MAX9724 toc35
ENTERING SHUTDOWN
MAX9724 toc34
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
VSHDN
5V/div
VIN_
1V/div
VIN_
1V/div
VOUT_
500mV/div
VOUT_
500mV/div
40μs/div
20μs/div
Pin Description
PIN
8
NAME
FUNCTION
TQFN
UCSP
1
C1
C1P
2
C2
PGND
3
C3
C1N
Flying Capacitor Negative Terminal. Connect a 1µF ceramic capacitor from C1P to C1N.
4
C4
PVSS
Charge-Pump Output. Connect to SVSS and bypass with a 1µF ceramic capacitor to PGND.
5
A2
SHDN
6
B3
INL
7
A1
SGND
8
B2
INR
9
B4
SVSS
10
A3
OUTR
Right-Channel Output
11
A4
OUTL
Left-Channel Output
12
B1
VDD
EP
—
EP
Flying Capacitor Positive Terminal. Connect a 1µF ceramic capacitor from C1P to C1N.
Power Ground. Connect to SGND.
Active-Low Shutdown Input
Left-Channel Input
Signal Ground. Connect to PGND.
Right-Channel Input
Amplifier Negative Supply. Connect to PVSS.
Positive Power-Supply Input. Bypass with a 1µF capacitor to PGND.
Exposed Paddle. Internally connected to SVSS. Connect to SVSS or leave unconnected.
_______________________________________________________________________________________
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
The MAX9724A/MAX9724B stereo headphone amplifiers feature Maxim’s DirectDrive architecture, eliminating 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 control, 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 conventional headphone amplifiers are unnecessary, conserving
board space, reducing system cost, and improving frequency response. The MAX9724A/MAX9724B 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 MAX9724A/MAX9724B also feature
thermal-overload and short-circuit protection.
MAX9724A/MAX9724B
Detailed Description
VOUT
VDD
VDD
VDD/2
GND
CONVENTIONAL DRIVER-BIASING SCHEME
VOUT
VDD
GND
2VDD
-VDD
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 headphone. Without these capacitors, a
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 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 headphone 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 32Ω load, results
in less than 47µA of DC current flow to the headphones.
DirectDrive BIASING SCHEME
Figure 1. Conventional Driver Output Waveform vs.
MAX9724A/MAX9724B Output Waveform
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 signals. 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 parasitic bond wire and trace inductance is minimized by
limiting the switching speed of the charge pump.
Although not typically required, additional high-frequency noise attenuation can be achieved by increasing 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 analog amplifiers demodulate the low-frequency envelope,
adding noise to the audio signal. The architecture of
_______________________________________________________________________________________
9
the MAX9724 addresses the problem of the RF susceptibility by rejecting RF noise and preventing it from coupling into the audio band.
The RF susceptibility of an amplifier can be measured
by placing the amplifier in an isolated chamber and subjecting 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 demodulated 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.
Table 1. RF Susceptibility Test Conditions
SETTING
50V/m
RF Modulation Type
Sine wave
RF Modulation Index
100%
RF Modulation Frequency
1kHz
In conventional single-supply audio amplifiers, the output-coupling capacitor contributes significantly to audible 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 discharged. 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 outputcoupling capacitors, this problem does not arise.
Additionally, the MAX9724A/MAX9724B feature extensive click-and-pop suppression that eliminates any audible transient sources internal to the device.
62dB IMPROVEMENT
AT 850MHz
RF SUSCEPTIBLE
AMPLIFIER
20
0
Shutdown
The MAX9724A/MAX9724B feature a < 0.1µA, lowpower shutdown mode that reduces quiescent current
consumption and extends battery life for portable applications. Drive SHDN low to disable the amplifiers and
the charge pump. In shutdown mode, the amplifier output impedance is set to 14kΩ||RF (RF is 30kΩ for the
MAX9724B). The amplifiers and charge pump are
enabled once SHDN is driven high.
Applications Information
Click-and-Pop Suppression
40
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 15kΩ resistor. 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 15kΩ x CIN
to eliminate clicks-and-pops caused by the input filter.
Power Dissipation
Under normal operating conditions, linear power amplifiers 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:
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
39dB IMPROVEMENT
AT 900MHz
67dB IMPROVEMENT
AT 1800MHz
49dB IMPROVEMENT
AT 1900MHz
MAX9724 fig02
TEST PARAMETER
RF Field Strength
AMPLIFIER OUTPUT AMPLITUDE (dBV)
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
-20
-40
-60
MAX9724
-80
-100
100
600
1100
1600
2100
2600
RF CARRIER FREQUENCY (MHz)
Figure 2. RF Susceptibility of the MAX9724 and a Typical Headphone Amplifier
10
______________________________________________________________________________________
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
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, allowing more heat to be transferred from the package to the
surrounding air.
Thermal-overload protection limits total power dissipation in the MAX9724A/MAX9724B. When the junction
temperature exceeds +150°C, the thermal protection
circuitry disables the amplifier output stage. The amplifiers 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 output signal is greater than the dynamic range of the system. The DirectDrive architecture of the MAX9724A/
MAX9724B has increased the dynamic range compared
to other single-supply amplifiers.
Maximum Output Swing
VDD < 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.
VDD > 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 feature ensures proper operation during brownout conditions 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 optimum DC level. Assuming zero-source impedance, the 3dB point of the highpass filter is given by:
f−3dB =
1
2πRINCIN
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 extended 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
Table 2. Suggested Capacitor Manufacturers
SUPPLIER
WEBSITE
PHONE
FAX
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
______________________________________________________________________________________
11
MAX9724A/MAX9724B
°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.
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
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 resistance 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.
AV = -RF/RIN (V/V)
Choose feedback resistor values in the tens of kΩ
range. Lower values may cause excessive power dissipation 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 (RF is equal to 30kΩ for 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 connected to the inverting terminal of the headphone amplifier
(20kΩ for 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 resistance of the input device.
RF
MAX9724A
LEFT
AUDIO
INPUT
RIN
RIGHT
AUDIO
INPUT
RIN
INL
OUTL
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 internally 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:
12
OUTR
INR
RF
Figure 3. Gain Setting for the MAX9724A
______________________________________________________________________________________
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
RMS OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
3.5
RMS OUTPUT VOLTAGE (V)
fIN = 1kHz
RL = 10kΩ
1% THD+N
3.0
LIMITED BY
ABS. MAXIMUM
RATINGS
2.5
RL = 1kΩ
1% THD+N
2.0
1.5
2.5
3.0
3.5
4.0
4.5
5.0
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 inadequate. 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 converter (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 limitations or create excessive EMI emissions on the
cables between devices.
5.5
SUPPLY VOLTAGE (V)
Figure 4. RMS Output Voltage vs. Supply Voltage
15kΩ
220pF
LEFT
AUDIO
INPUT
1μF
7.5kΩ
7.5kΩ
MAX9724A
INL
OUTL
1.2nF
STEREO
DAC
LINE IN DEVICE
10kΩ
1.2nF
RIGHT
AUDIO
INPUT
1μF
OUTR
7.5kΩ
7.5kΩ
INR
10kΩ
220pF
15kΩ
Figure 5. MAX9724A Line Out Amplifier and Filter Block Configuration
______________________________________________________________________________________
13
MAX9724A/MAX9724B
Lineout Amplifier and Filter Block
The MAX9724A can be used as an audio line driver
capable of providing 2VRMS into 10kΩ loads with a single 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
To suppress this noise, and to provide a 2VRMS standard 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-supply 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.
MAX9724A ACTIVE FILTER GAIN
vs. FREQUENCY
10
RL = 10kΩ
5
0
-5
GAIN (dB)
MAX9724A/MAX9724B
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
-10
-15
-20
-25
-30
-35
1k
10k
100k
Figure 6. Frequency Response of Active Filter of Figure 4
UCSP Applications Information
For the latest application details on UCSP construction,
dimensions, tape carrier information, printed circuit
board techniques, bump-pad layout, and recommended reflow temperature profile, as well as the latest information on reliability testing results, refer to the
Application Note UCSP—A Wafer-Level Chip-Scale
Package available on Maxim’s website at www.maximic.com/ucsp.
14
1M
FREQUENCY (Hz)
______________________________________________________________________________________
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
VDD
0.1μF
15kΩ
1μF
15kΩ
INR
VDD
PVDD
BIAS
OUTR+
OUTR-
1μF
MAX9710
GND
PGND
MUTE
0.1μF 15kΩ
OUTL-
SHDN
OUTL+
INL
VDD
15kΩ
μCONTROLLER
100kΩ
100kΩ
0.1μF
STEREO
DAC
OUTL
SHDN
O.47μF
MAX9724B OUTR
INL
SGND
O.47μF
INR
PGND
VDD
PVSS
1μF
SVSS
C1P
C1N
VDD
1μF
1μF
______________________________________________________________________________________
15
MAX9724A/MAX9724B
System Diagram
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
MAX9724A/MAX9724B
Functional Diagram/Typical Operating Circuits
2.7V TO 5.5V
ON
C3
1μF
OFF
CIN R
IN*
0.47μF 20kΩ
LEFT
AUDIO
INPUT
RF*
30kΩ
12
(B1)
5
(A2)
6
(B3)
VDD
SHDN
INL
VDD
11
OUTL (A4)
HEADPHONE
JACK
1
(C1) C1P
SVSS
UVLO/
SHUTDOWN
CONTROL
CLICK-AND-POP
SUPPRESSION
CHARGE
PUMP
C1
1μF
SGND
VDD
3
(C3) C1N
OUTR
10
(A3)
MAX9724A
PVSS
4
(C4)
SVSS PGND
2
9
(B4) (C2)
C2
1μF
SVSS
SGND
7
(A1)
INR
8
(B2)
RIGHT
AUDIO
INPUT
CIN
RIN*
0.47μF 20kΩ
RF*
30kΩ
*RIN AND RF VALUES ARE CHOSEN FOR A GAIN -1.5V/V.
( ) UCSP PACKAGE
16
______________________________________________________________________________________
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
2.7V TO 5.5V
ON
C3
1μF
OFF
LEFT
AUDIO
INPUT
CIN
0.47μF
12
(B1)
5
(A2)
6
(B3)
VDD
SHDN
INL
RIN*
20kΩ
RF*
30kΩ
VDD
11
OUTL (A4)
HEADPHONE
JACK
1
(C1) C1P
VSS
UVLO/
SHUTDOWN
CONTROL
CLICK-AND-POP
SUPPRESSION
CHARGE
PUMP
C1
1μF
SGND
VDD
3
(C3) C1N
MAX9724B
OUTR
RIN
20kΩ
10
(A3)
SVSS
RF
30kΩ
PVSS
SVSS
PGND
SGND
4
(C4)
C2
1μF
9
(B4)
2
(C2)
7
(A1)
INR
8
(B2)
CIN
RIGHT 0.47μF
AUDIO
INPUT
( ) UCSP PACKAGE
______________________________________________________________________________________
17
MAX9724A/MAX9724B
Functional Diagram/Typical Operating Circuits (continued)
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
INR
SGND
TOP VIEW
SVSS
MAX9724A/MAX9724B
Pin Configurations
TOP VIEW (BUMPS ON BOTTOM)
9
8
7
1
2
3
4
MAX9724A/MAX9724B
OUTR 10
MAX9724A
MAX9724B
OUTL 11
6
INL
5
SHDN
4
PVSS
A
SGND
SHDN
OUTR
OUTL
VDD
INR
INL
SVSS
C1P
PGND
C1N
PVSS
B
VDD 12
+
3
C
C1N
2
PGND
C1P
1
TQFN
UCSP
Package Information
Chip Information
PROCESS: BiCMOS
18
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
______________________________________________________________________________________
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
REVISION
NUMBER
REVISION
DATE
0
5/05
Initial release
1
1/06
Added RF immunity to General Description, Features, and Detailed
Description.
2
11/06
Added UCSP package.
3
3/07
Updated Electrical Characteristics table and Typical Operating
Characteristics.
4
6/07
Corrected Pin Description, Pin Configuration, and Functional
Diagrams/Typical Operating Circuits with new UCSP information.
5
3/08
Updated Absolute Maximum Ratings and Click-and-Pop Suppression
section.
6
3/09
Updated Ordering Information, style changes
DESCRIPTION
PAGES
CHANGED
—
1, 7
1–3, 6, 9, 12, 14–16
1–6, 17, 18
1–6, 12, 14–16
2, 10
1, 10, 18, 19
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.
MAX9724A/MAX9724B
Revision History
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