MAXIM MAX9700 User Manual
General Description
The MAX9700 mono class D audio power amplifier provides class AB amplifier performance with class D efficiency, conserving board space and extending battery
life. Using a class D architecture, the MAX9700 delivers
1.2W into an 8Ω load while offering efficiencies above
90%. A low-EMI modulation scheme renders the traditional class D output filter unnecessary.
The MAX9700 offers two modulation schemes: a fixedfrequency (FFM) mode, and a spread-spectrum (SSM)
mode that reduces EMI-radiated emissions due to the
modulation frequency. Furthermore, the MAX9700 oscillator can be synchronized to an external clock through
the SYNC input, allowing the switching frequency to be
user defined. The SYNC input also allows multiple
MAX9700s to be cascaded and frequency locked, minimizing interference due to clock intermodulation. The
device utilizes a fully differential architecture, a fullbridged output, and comprehensive click-and-pop suppression. The gain of the MAX9700 is set internally
(MAX9700A: 6dB, MAX9700B: 12dB, MAX9700C:
15.6dB, MAX9700D: 20dB), further reducing external
component count.
The MAX9700 features high 72dB PSRR, a low 0.01%
THD+N, and SNR in excess of 90dB. Short-circuit and
thermal-overload protection prevent the device from
damage during a fault condition. The MAX9700 is available in 10-pin TDFN (3mm
✕
3mm ✕0.8mm), 10-pin
µMAX®, and 12-bump UCSP™ (1.5mm ✕2mm ✕ 0.6mm)
packages. The MAX9700 is specified over the extended
-40°C to +85°C temperature range.
Applications
Features
♦ Filterless Amplifier Passes FCC Radiated
Emissions Standards with 100mm of Cable
♦ Unique Spread-Spectrum Mode Offers 5dB
Emissions Improvement Over Conventional
Methods
♦ Optional External SYNC Input
♦ Simple Master-Slave Setup for Stereo Operation
♦ 94% Efficiency
♦ 1.2W into 8Ω
♦ Low 0.01% THD+N
♦ High PSRR (72dB at 217Hz)
♦ Integrated Click-and-Pop Suppression
♦ Low Quiescent Current (4mA)
♦ Low-Power Shutdown Mode (0.1µA)
♦ Short-Circuit and Thermal-Overload Protection
♦ Available in Thermally Efficient, Space-Saving
Packages
10-Pin TDFN (3mm x 3mm x 0.8mm)
10-Pin µMAX
12-Bump UCSP (1.5mm x 2mm x 0.6mm)
MAX9700
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
________________________________________________________________
Maxim Integrated Products
1
1
2
3
4
5
10
9
8
7
6
PV
DD
OUT-
OUT+
PGNDGND
IN-
IN+
V
DD
MAX9700
TDFN/μMAX
TOP VIEW
SYNCSHDN
Pin Configurations
Ordering Information
MAX9700
DIFFERENTIAL
AUDIO INPUT
SYNC
INPUT
V
DD
OSCILLATOR
MODULATOR
AND H-BRIDGE
Block Diagram
19-3030; Rev 2; 10/08
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.
Cellular Phones
PDAs
MP3 Players
Portable Audio
PART
TEMP RANGE
PINPACKAGE
TOP
MARK
MAX9700AETB
ACM
MAX9700AEUB
10 µMAX —
MAX9700AEBC-T
12 UCSP —
MAX9700BETB
ACI
MAX9700BEUB
10 µMAX —
MAX9700BEBC-T
12 UCSP —
Pin Configurations continued at end of data sheet.
Ordering Information continued and Selector Guide appears
at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
*EP = Exposed pad.
-40oC to +85oC 10 TDFN-EP*
-40oC to +85oC
-40oC to +85oC
-40oC to +85oC 10 TDFN-EP*
-40oC to +85oC
-40oC to +85oC
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD= PVDD= V
SHDN
= 3.3V, V
GND
= V
PGND
= 0V, SYNC = GND (FFM), RL= 8Ω, RLconnected between OUT+ and OUT-,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +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.
VDDto GND..............................................................................6V
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 Into/Out of PV
DD
/PGND/OUT_........±600mA
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)
10-Pin TDFN (derate 24.4mW/°C above +70°C) .....1951.2mW
10-Pin µMAX (derate 5.6mW/
o
C above +70°C) .........444.4mW
12-Bump UCSP (derate 6.1mW/°C above +70°C)........484mW
Junction Temperature......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Bump Temperature (soldering)
Reflow ..........................................................................+235°C
MAX9700
PARAMETER
CONDITIONS
UNITS
GENERAL
Supply Voltage Range V
DD
Inferred from PSRR test 2.5 5.5 V
Quiescent Current I
DD
45.2mA
Shutdown Current I
SHDN
0.1 10 µA
Turn-On Time t
ON
30 ms
Input Resistance R
IN
TA = +25°C 12 20 kΩ
Input Bias Voltage V
BIAS
Either input
V
MAX9700A 6
MAX9700B 12
MAX9700C
Voltage Gain A
V
MAX9700D 20
dB
TA = +25°C
Output Offset Voltage V
OS
T
MIN
≤ TA ≤ T
MAX
mV
Common-Mode Rejection Ratio CMRR fIN = 1kHz, input referred 72 dB
VDD = 2.5V to 5.5V, TA = +25°C 50 70
f
RIPPLE
= 217Hz 72
Power-Supply Rejection Ratio
(Note 3)
PSRR
200mV
P-P
ripple
f
RIPPLE
= 20kHz 55
dB
RL = 8Ω
Output Power P
OUT
THD+N = 1%
R
L
= 6Ω
mW
RL = 8Ω,
P
OUT
= 125mW
Total Harmonic Distortion
Plus Noise
fIN = 1kHz, either
FFM or SSM
R
L
= 6Ω,
P
OUT
= 125mW
%
SYMBOL
MIN TYP MAX
0.73 0.83 0.93
THD+N
15.6
±11 ±80
450
800
0.01
0.01
±120
MAX9700
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD= PVDD= V
SHDN
= 3.3V, V
GND
= V
PGND
= 0V, SYNC = GND (FFM), RL= 8Ω, RLconnected between OUT+ and OUT-,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°C.) (Notes 1, 2)
Note 1: All devices are 100% production tested at T
A
= +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
= 4Ω, L = 33µH.
For R
L
= 8Ω, L = 68µH. For RL= 16Ω, L = 136µH.
Note 3: PSRR is specified with the amplifier inputs connected to GND through C
IN
.
PARAMETER
CONDITIONS
UNITS
FFM 89
BW = 22Hz
to 22kHz
SSM 87
FFM 92
Signal-to-Noise Ratio SNR V
OUT
= 2V
RMS
SSM 90
dB
SYNC = GND 980
SYNC = unconnected
Oscillator Frequency f
OSC
SYNC = VDD (SSM mode)
kHz
SYNC Frequency Lock Range 800
kHz
Efficiency η P
OUT
= 500mW, fIN = 1kHz 94 %
V
IH
2
Input Thresholds
V
IL
0.8
V
SHDN Input Leakage Current ±1µA
SYNC Input Current ±5µA
ELECTRICAL CHARACTERISTICS
(VDD= PVDD= V
SHDN
= 5V, V
GND
= V
PGND
= 0V, SYNC = GND (FFM), RL= 8Ω, RLconnected between OUT+ and OUT-, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°C.) (Notes 1, 2)
PARAMETER
CONDITIONS
UNITS
Quiescent Current I
DD
5.2 mA
Shutdown Current I
SHDN
0.1 µA
Common-Mode Rejection Ratio CMRR f = 1kHz, input referred 72 dB
f = 217Hz 72
Power-Supply Rejection Ratio PSRR
f = 20kHz 55
dB
RL = 16Ω
RL = 8Ω
Output Power P
OUT
THD+N = 1%
R
L
= 6Ω
mW
Total Harmonic Distortion
Plus Noise
f = 1kHz, either
FFM or SSM
%
FFM
BW = 22Hz to
22kHz
SSM
FFM
Signal-to-Noise Ratio SNR
V
OUT
=
3V
RMS
A-weighted
SSM
dB
DIGITAL INPUTS (SHDN, SYNC)
SYMBOL
SYMBOL
MIN TYP MAX
A-weighted
1100 1220
1280 1450 1620
1220
±120
2000
MIN TYP MAX
200mV
THD+N
ripple
P-P
700
1200
1600
RL = 8Ω, P
RL = 4Ω, P
= 125mW 0.015
OUT
= 125mW 0.02
OUT
92.5
90.5
95.5
93.5
100
0 0.5 1.0 1.5 2.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9700 toc04
OUTPUT POWER (W)
THD+N (%)
VDD = 5V
R
L
= 8Ω
f = 1kHz
f = 10kHz
f = 100Hz
100
0 0.2 0.4 0.6 0.8 1.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9700 toc05
OUTPUT POWER (W)
THD+N (%)
VDD = 5V
R
L
= 16Ω
f = 10kHz
f = 1kHz
f = 100Hz
100
0 0.5 1.0 1.5 2.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT VOLTAGE
MAX9700 toc06
OUTPUT POWER (W)
THD+N (%)
2.5
3.0 3.5
f = 10kHz
f = 1kHz
f = 100Hz
VDD = 5V
R
L
= 4Ω
100
0 0.1 0.2 0.3 0.4 0.5
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9700 toc07
OUTPUT POWER (W)
THD+N (%)
VDD = 2.5V
R
L
= 8Ω
V
CM
= 1.25V
NO INPUT CAPACITORS
DIFFERENTIAL
INPUT
SINGLE ENDED
100
0 0.5 1.0 1.5 2.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9700 toc08
OUTPUT POWER (W)
THD+N (%)
VDD = 5V
f = 1kHz
R
L
= 8Ω
FFM
(SYNC UNCONNECTED)
SSM
FFM
(SYNC = GND)
100
0 0.5 1.0 1.5 2.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9700 toc09
OUTPUT POWER (W)
THD+N (%)
VDD = 5V
f = 1kHz
R
L
= 8Ω
f
SYNC
= 800kHz
f
SYNC
= 2MHz
f
SYNC
= 1.4MHz
MAX9700
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VDD= 3.3V, SYNC = GND (SSM), TA= +25°C, unless otherwise noted.)
0.001
10 100k10k100 1k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
1
0.1
0.01
MAX9700 toc01
FREQUENCY (Hz)
THD+N (%)
V
DD
= +5V
R
L
= 8Ω
P
OUT
= 300mW
P
OUT
= 125mW
0.001
10 100k10k100 1k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
1
0.1
0.01
MAX9700 toc02
FREQUENCY (Hz)
THD+N (%)
V
DD
= +3.3V
R
L
= 8Ω
P
OUT
= 300mW
P
OUT
= 125mW
0.001
10 100k10k100 1k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
1
0.1
0.01
MAX9700 toc03
FREQUENCY (Hz)
THD+N (%)
VDD = +3.3V
R
L
= 8Ω
P
OUT
= 125mW
SSM MODE
FFM MODE
MAX9700
Typical Operating Characteristics (continued)
(VDD= 3.3V, SYNC = GND (SSM), TA= +25°C, unless otherwise noted.)
10
0 0.5 1.0 1.5 2.0 2.5 3.0
1
0.1
0.01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. COMMON-MODE VOLTAGE
MAX9700 toc10
COMMON-MODE VOLTAGE (V)
THD+N (%)
VDD = 3.3V
R
L
= 8Ω
f = 1kHz
P
OUT
= 300mW
DIFFERENTIAL INPUT
EFFICIENCY vs. OUTPUT POWER
MAX9700toc11
OUTPUT POWER (W)
EFFICIENCY (%)
1.20.90.60.3
10
20
30
40
50
60
70
80
90
100
0
01.5
RL = 4Ω
RL = 8Ω
VDD = 3.3V
f = 1kHz
EFFICIENCY vs. OUTPUT POWER
MAX9700toc12
OUTPUT POWER (W)
EFFICIENCY (%)
2.01.50.5
10
20
30
40
50
60
70
80
90
100
0
03.0
RL = 8Ω
R
L
= 4Ω
VDD = 5V
f = 1kHz
1.0
2.5
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
_______________________________________________________________________________________ 5
0
30
20
10
50
40
90
80
70
60
100
2.5 3.0 3.5 4.0 4.5 5.0 5.5
EFFICIENCY vs. SUPPLY VOLTAGE
MAX9700 toc13
SUPPLY VOLTAGE (V)
EFFICIENCY (%)
RL = 8Ω
f = 1kHz
P
OUT
= MAX (THD+N = 1%)
RL = 4Ω
0
30
20
10
50
40
90
80
70
60
100
800 1000 1200 1400 18001600 2000
EFFICIENCY
vs. SYNC INPUT FREQUENCY
MAx9700 toc14
SYNC FREQUENCY (kHz)
EFFICIENCY (%)
VDD = 3.3V
f = 1kHz
P
OUT
= 300mW
R
L
= 8Ω
OUTPUT POWER vs.
SUPPLY VOLTAGE
MAX9700toc15
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
5.04.54.03.53.0
1.5
2.0
2.5
3.0
3.5
0
2.5 5.5
1.0
0.5
RL = 4Ω
THD+N = 10%
RL = 4Ω
THD+N = 1%
RL = 8Ω
THD+N = 10%
RL = 8Ω
THD+N = 1%
f = 1kHz
OUTPUT POWER vs. LOAD RESISTANCE
MAX9700toc16
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
908070605040302010
400
800
1200
1600
2000
0
0 100
VDD = 5V
f = 1kHz
THD+N = 1%
VDD = 3.3V
0
-100
10 100 1k 10k 100k
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
-80
MAX9700TOC17
FREQUENCY (Hz)
CMRR (dB)
-60
-40
-20
-30
-50
-70
-90
-10
INPUT REFERRED
V
IN
= 200mV
P-P
0
-100
10 100 1k 10k 100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-80
MAX9700TOC18
FREQUENCY (Hz)
PSRR (dB)
-60
-40
-20
-30
-50
-70
-90
-10
OUTPUT REFERRED
INPUTS AC GROUNDED
V
DD
= 3.3V
MAX9700
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
6 _______________________________________________________________________________________
-140
-100
-120
-60
-80
-20
-40
0
OUTPUT FREQUENCY SPECTRUM
MAX9700 toc22
FREQUENCY (Hz)
OUTPUT MAGNITUDE (dBV)
0 5k 10k 15k 20k
SSM MODE
V
OUT
= -60dBV
f = 1kHz
R
L
= 8Ω
A-WEIGHTED
0
-100
1M 10M 100M 1G
WIDEBAND OUTPUT SPECTRUM
(FFM MODE)
-80
MAX9700 toc23
FREQUENCY (Hz)
OUTPUT AMPLITUDE (dB)
-60
-40
-20
-30
-50
-70
-90
-10
RBW = 10kHz
0
-100
1M 10M 100M 1G
WIDEBAND OUTPUT SPECTRUM
(SSM MODE)
-80
MAX9700 toc24
FREQUENCY (Hz)
OUTPUT AMPLITUDE (dB)
-60
-40
-20
-30
-50
-70
-90
-10
RBW = 10kHz
TURN-ON/TURN-OFF RESPONSE
MAX9700 toc25
MAX9700
OUTPUT
SHDN
0V
250mV/div
3V
10ms/div
f = 1kHz
R
L
= 8Ω
-140
-100
-120
-60
-80
-20
-40
0
OUTPUT FREQUENCY SPECTRUM
MAX9700 toc21
FREQUENCY (Hz)
OUTPUT MAGNITUDE (dBV)
0 5k 10k 15k 20k
SSM MODE
V
OUT
= -60dBV
f = 1kHz
R
L
= 8Ω
UNWEIGHTED
GSM POWER-SUPPLY REJECTION
MAX9700 toc19
MAX9700
OUTPUT
V
DD
100μV/div
500mV/div
2ms/div
f = 217Hz
INPUT LOW = 3V
INPUT HIGH = 3.5V
DUTY CYCLE = 88%
R
L
= 8Ω
-140
-100
-120
-60
-80
-20
-40
0
OUTPUT FREQUENCY SPECTRUM
MAX9700 toc20
FREQUENCY (Hz)
OUTPUT MAGNITUDE (dBV)
0 5k 10k 15k 20k
FFM MODE
V
OUT
= -60dBV
f = 1kHz
R
L
= 8Ω
UNWEIGHTED
Typical Operating Characteristics (continued)
(VDD= 3.3V, SYNC = GND (SSM), TA= +25°C, unless otherwise noted.)
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