General Description
The MAX9701 stereo class D audio power amplifier pro-
vides class AB amplifier audio performance with the
benefits of class D efficiency, eliminating the need for a
heatsink while extending battery life. The MAX9701
delivers up to 1.3W per channel into an 8 load while
offering 87% efficiency. Maxim's next-generation, low-
EMI modulation scheme allows the amplifier to operate
without an external LC filter while still meeting FCC EMI
emission levels.
The MAX9701 offers two modulation schemes: a fixed-fre-
quency (FFM) mode, and a spread-spectrum (SSM)
mode that reduces EMI-radiated emissions. The
MAX9701 oscillator can be synchronized to an external
clock through the SYNC input, allowing synchronization of
multiple Maxim class D amplifiers. The sync output
(SYNC_OUT) can be used for a master-slave application
where more channels are required. The MAX9701 fea-
tures a fully differential architecture, a full bridge-tied load
(BTL) output, and comprehensive click-and-pop suppres-
sion. The device features internally set gains of 0dB, 6dB,
12dB, and 18dB selected through two gain-select inputs,
further reducing external component count.
The MAX9701 features high 80dB PSRR, less than 0.1%
THD+N, and SNR in excess of 88dB. Short-circuit and
thermal-overload protection prevent the device from
being damaged during a fault condition. The MAX9701 is
available in 24-pin thin QFN-EP (4mm x 4mm x 0.8mm),
20-pin TSSOP, and 20-bump UCSPTM (2mm x 2.5mm x
0.6mm) packages. The MAX9701 is specified over the
extended -40°C to +85°C temperature range.
Applications
Cellular Phones
Notebooks
Handheld Gaming Consoles
Docking Stations
MP3 Players
Features
Patented Spread-Spectrum Modulation Lowers
Radiated Emissions
Single-Supply Operation (2.5V to 5.5V)
1.3W Stereo Output (8, V
DD
= 5V, THD+N = 1%)
No LC Output Filter Required
87% Efficiency (R
L
= 8, P
O
= 1000mW)
Less Than 0.1% THD+N
High 80dB PSRR
Fully Differential Inputs
Integrated Click-and-Pop Suppression
Typical Low Quiescent Current (9mA)
Typical Low-Power Shutdown Mode (0.1µA)
Short-Circuit and Thermal-Overload Protection
Available in Thermally Efficient, Space-Saving
Packages
24-Pin Thin QFN-EP (4mm x 4mm x 0.8mm)
20-Pin TSSOP
20-Bump UCSP (2mm x 2.5mm x 0.6mm)
MAX9701
1.3W, Filterless, Stereo Class D Audio
Power Amplifier
________________________________________________________________ Maxim Integrated Products
1
MAX9701
GAIN2
GAIN1
V
DD
GAIN
RIGHT
MODULATOR
AND H-BRIDGE
SYNC
OSCILLATOR
LEFT
MODULATOR
AND H-BRIDGE
INR+
INR-
INL+
INL-
SYNC_OUT
Block Diagram
Ordering Information
19-3457; Rev 0; 6/05
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
PART
TEMP RANGE
PIN-PACKAGE
MAX9701EBP-T
-40°C to +85°C
20 UCSP-20
MAX9701EUP+
-40°C to +85°C
20 TSSOP
MAX9701ETG+
-40°C to +85°C
24 TQFN-EP
Pin Configurations appear at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
+ Denotes lead-free package.
MAX9701
1.3W, Filterless, Stereo Class D Audio
Power Amplifier
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
DD
= PV
DD
=
SHDN = 3.3V, GND = PGND = 0V, SYNC = 0V (FFM), gain = 6dB (GAIN1 = 0, GAIN2 = 1), R
L
connected between
OUT+ and OUT-, R
L
= , T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
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.
V
DD
to GND..............................................................................6V
V
DD
to PV
DD
..........................................................-0.3V to +0.3V
PV
DD
to PGND .........................................................................6V
GND to PGND .......................................................-0.3V to +0.3V
All Other Pins to GND.................................-0.3V to (V
DD
+ 0.3V)
Continuous Current In/Out of PV
DD
, PGND, OUT_ .........±800mA
Continuous Input Current (all other pins)..........................±20mA
Duration of OUT_ Short Circuit to GND or PV
DD
........Continuous
Duration of Short Circuit Between OUT+ and OUT- ......Continuous
Continuous Power Dissipation (T
A
= +70°C)
20-Bump UCSP (derate 10mW/°C above +70°C) ...........800mW
20-Pin TSSOP (derate 11mW/°C above +70°C) ...........879.1mW
24-Pin Thin QFN (derate 20.8mW/°C above +70°C) ..1666.7mW
Junction Temperature ......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature (soldering) Reflow............................+235°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
GENERAL
Supply Voltage Range
V
DD
Inferred from PSRR test
2.5
5.5
V
V
DD
= 3.3V, per channel
4.5
8
Quiescent Current
I
DD
V
DD
= 5V, per channel
6.3
10
mA
Shutdown Current
I
SHDN
0.1
10
µA
Common-Mode Rejection Ratio
CMRR
f
IN
= 1kHz
66
dB
Input Bias Voltage
V
BIAS
1.125
1.25
1.375
V
Turn-On Time
t
ON
40
ms
T
A
= +25
o
C
±10
±30
Output Offset Voltage
V
OS
T
MIN
< T
A
< T
MAX
±55
mV
V
DD
= 2.5V to 5.5V, V
IN
= 0V
60
80
f
RIPPLE
= 217Hz
72
Power-Supply Rejection Ratio
PSRR
100mV
P-P
ripple,
V
IN
= 0V
f
RIPPLE
= 20kHz
50
dB
R
L
= 8
460
V
DD
= 3.3V
R
L
= 4
750
R
L
= 8
1300
Output Power (Note 3)
P
OUT
THD+N = 1%,
T
A
= +25
o
C
V
DD
= 5V
R
L
= 4
2200
mW
R
L
= 8
(P
OUT
= 300mW), f = 1kHz
0.08
Total Harmonic Distortion Plus
Noise (Note 3)
THD+N
R
L
= 4
(P
OUT
= 400mW), f = 1kHz
0.15
%
FFM
86
BW = 22Hz
to 22kHz
SSM
86
FFM
88.5
Signal-to-Noise Ratio
SNR
V
OUT
= 1V
RMS
A-weighted
SSM
88.5
dB
SYNC = GND
950
1100
1250
SYNC = unconnected
1200
1400
1600
Oscillator Frequency
f
OSC
SYNC = V
DD
1200
±60
kHz
Minimum On-Time
t
MIN
200
ns
SYNC Frequency Lock Range
f
SYNC
1000
1600
kHz
MAX9701
1.3W, Filterless, Stereo Class D Audio
Power Amplifier
_______________________________________________________________________________________
3
Note 1: All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 2: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For R
L
= 4, L = 33µH.
For R
L
= 8, L = 68µH.
Note 3: When driving speakers below 4 with large signals, exercise care to avoid violating the absolute maximum rating for continuous
output current.
Note 4: Testing performed with 8 resistive load in series with 68µH inductive load connected across the BTL output. Mode transi-
tions are controlled by
SHDN. K
CP
level is calculated as: 20 x log[(peak voltage under normal operation at rated power
level) / (peak voltage during mode transition, no input signal)]. Units are expressed in dB.
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
=
SHDN = 3.3V, GND = PGND = 0V, SYNC = 0V (FFM), gain = 6dB (GAIN1 = 0, GAIN2 = 1), R
L
connected between
OUT+ and OUT-, R
L
= , T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SYNC_OUT Capacitance Drive
C
SYNC_OUT
100
pF
Bridge-tied capacitance
200
Capacitive Drive
C
L
Single ended
400
pF
Into shutdown
66.16
Click-and-Pop Level
K
CP
Peak reading, TH D + N = 1%
A-weighted, 32 samples
per second (Note 4)
Out of
shutdown
66.26
dB
V
DD
= 3.3V, P
OUT
= 500mW per channel,
f
IN
= 1kHz, R
L
= 8
87
Efficiency
V
DD
= 5V, P
OUT
= 1000mW per channel,
f
IN
= 1kHz, R
L
= 8
87.4
%
GAIN1 = 0, GAIN2 = 0
10.5
15
19.5
GAIN1 = 1, GAIN2 = 0
25
GAIN1 = 0, GAIN2 = 1
37.4
Input Resistance
R
IN
GAIN1 = 1, GAIN2 = 1
50
k
GAIN1 = 0, GAIN2 = 0
18
GAIN1 = 1, GAIN2 = 0
12
GAIN1 = 0, GAIN2 = 1
6
Gain
A
V
GAIN1 = 1, GAIN2 = 1
0
dB
Channel-to-Channel Gain
Tracking
1
%
Crosstalk
L to R, R to L, f = 10kHz, R
L
= 8
,
P
OUT
= 300mW
70
dB
DIGITAL INPUTS (
SHDN, SYNC, GAIN1, GAIN2)
Input-Voltage High
V
INH
2
V
Input-Voltage Low
V
INL
0.8
V
Input Leakage Current
(
SHDN, GAIN1, GAIN2)
±1
µA
V
IN
= GND, normal operation
-15
-7
Input Leakage Current (SYNC)
V
IN
= V
DD
, normal operation
12
25
µA
DIGITAL OUTPUTS (SYNC_OUT)
Output-Voltage High
V
OH
I
OH
= 3mA, V
DD
= 3.3V
2.4
V
Output-Voltage Low
V
OL
I
OL
= 3mA
0.08
V
MAX9701
1.3W, Filterless, Stereo Class D Audio
Power Amplifier
4
_______________________________________________________________________________________
Typical Operating Characteristics
(V
DD
= PV
DD
=
SHDN = 3.3V, GND = PGND = 0V, SYNC = V
DD
(SSM), gain = 6dB (GAIN1 = 0, GAIN2 = 1)).
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX9701 toc01
FREQUENCY (Hz)
THD+N (%)
10k
1k
100
0.1
1
10
0.01
10
100k
V
DD
= 5V
R
L
= 4
OUTPUT POWER = 300mW
OUTPUT POWER = 100mW
OUTPUT POWER = 600mW
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX9701 toc02
FREQUENCY (Hz)
THD+N (%)
10k
1k
100
0.1
1
10
0.01
10
100k
V
DD
= 5V
R
L
= 8
OUTPUT POWER = 250mW
OUTPUT POWER = 100mW
OUTPUT POWER = 500mW
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX9701 toc03
FREQUENCY (Hz)
THD+N (%)
10k
1k
100
0.1
1
10
0.01
10
100k
V
DD
= 3.3V
R
L
= 4
OUTPUT POWER = 300mW
OUTPUT POWER = 100mW
OUTPUT POWER = 600mW
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX9701 toc04
FREQUENCY (Hz)
THD+N (%)
10k
1k
100
0.1
1
10
0.01
10
100k
V
DD
= 3.3V
R
L
= 8
OUTPUT POWER = 100mW
OUTPUT POWER = 400mW
OUTPUT POWER = 250mW
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX9701 toc05
FREQUENCY (Hz)
THD+N (%)
10k
1k
100
0.1
1
10
0.01
10
100k
V
DD
= 5V
R
L
= 8
P
OUT
= 800mW
FFM
SSM
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9701 toc06
OUTPUT POWER (W)
THD+N (%)
2.5
2.0
1.5
1.0
0.5
0.1
1
10
100
0.01
0
3.0
V
DD
= 5V
R
L
= 4
f
IN
= 10kHz
f
IN
= 20kHz
f
IN
= 1kHz
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9701 toc07
OUTPUT POWER (W)
THD+N (%)
1.5
1.0
0.5
0.01
0.1
1
10
100
0.001
0
2.0
V
DD
= 5V
R
L
= 8
f
IN
= 10kHz
f
IN
= 20kHz
f
IN
= 1kHz
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9701 toc08
OUTPUT POWER (W)
THD+N (%)
1.0
0.8
0.6
0.4
0.2
0.1
1
10
100
0.01
0
1.2
V
DD
= 3.3V
R
L
= 4
f
IN
= 10kHz
f
IN
= 20kHz
f
IN
= 1kHz
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9701 toc09
OUTPUT POWER (mW)
THD+N (%)
600
500
400
300
200
100
0.1
1
10
100
0.01
0
700
V
DD
= 3.3V
R
L
= 8
f
IN
= 10kHz
f
IN
= 20kHz
f
IN
= 1kHz
MAX9701
1.3W, Filterless, Stereo Class D Audio
Power Amplifier
_______________________________________________________________________________________
5
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9701 toc10
OUTPUT POWER (W)
THD+N (%)
1.6
1.2
0.8
0.4
0.01
0.1
1
10
100
0.001
0
2.0
V
DD
= 5V
R
L
= 8
f
IN
= 1kHz
SSM
FFM
EFFICIENCY vs. OUTPUT POWER
MAX9701 toc11
OUTPUT POWER (W)
EFFICIENCY (%)
2.0
1.5
1.0
0.5
10
20
30
40
50
60
70
80
90
100
0
0
2.5
V
DD
= 5V
f
IN
= 1kHz
P
OUT
= P
OUTLEFT
+ P
OUTRIGHT
R
L
= 8
R
L
= 4
EFFICIENCY vs. OUTPUT POWER
MAX9701 toc12
OUTPUT POWER (W)
EFFICIENCY (%)
1.0
0.8
0.6
0.4
0.2
10
20
30
40
50
60
70
80
90
100
0
0
1.2
V
DD
= 3.3V
f
IN
= 1kHz
P
OUT
= P
OUTLEFT
+ P
OUTRIGHT
R
L
= 8
R
L
= 4
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX9701 toc13
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
5.0
4.5
4.0
3.5
3.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
2.5
5.5
R
L
= 4
A
V
= 12dB
f
IN
= 1kHz
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX9701 toc14
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
5.0
4.5
4.0
3.5
3.0
0.4
0.8
1.2
1.6
2.0
0
2.5
5.5
R
L
= 8
A
V
= 12dB
f
IN
= 1kHz
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. LOAD RESISTANCE
MAX9701 toc15
LOAD RESISTANCE ()
OUTPUT POWER (W)
80
60
40
20
0.5
1.0
1.5
2.0
2.5
3.0
0
0
100
V
DD
= 5V
f
IN
= 1kHz
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. LOAD RESISTANCE
MAX9701 toc16
LOAD RESISTANCE ()
OUTPUT POWER (W)
80
60
40
20
0.4
0.8
1.2
1.6
2.0
0
0
100
f
IN
= 1kHz
THD+N = 10%
THD+N = 1%
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX9701 toc17
FREQUENCY (Hz)
PSRR (dB)
10k
1k
100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
10
100k
V
RIPPLE
= 100mV
P-P
R
L
= 8
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
MAX9701 toc18
FREQUENCY (Hz)
CMRR (dB)
10k
1k
100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
10
100k
V
CM
= 100mV
P-P
R
L
= 8
V
DD
= 5V
V
DD
= 3.3V
Typical Operating Characteristics (continued)
(V
DD
= PV
DD
=
SHDN = 3.3V, GND = PGND = 0V, SYNC = V
DD
(SSM), gain = 6dB (GAIN1 = 0, GAIN2 = 1)).
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