19-3030; Rev 2; 10/08
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
General Description
The MAX9700 mono class D audio power amplifier pro-
vides class AB amplifier performance with class D effi-
ciency, 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 tradi-
tional class D output filter unnecessary.
The MAX9700 offers two modulation schemes: a fixed-
frequency (FFM) mode, and a spread-spectrum (SSM)
mode that reduces EMI-radiated emissions due to the
modulation frequency. Furthermore, the MAX9700 oscil-
lator 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, mini-
mizing interference due to clock intermodulation. The
device utilizes a fully differential architecture, a full-
bridged output, and comprehensive click-and-pop sup-
pression. 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 avail-
able 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.
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
Ordering Information
PART
MAX9700AETB
MAX9700AEUB
MAX9700AEBC-T
MAX9700BETB
MAX9700BEUB
MAX9700BEBC-T
TEMP RANGE
-40
o
C to +85
o
C
-40
o
C to +85
o
C
-40 C to +85 C
-40 C to +85 C
-40
o
C to +85
o
C
-40 C to +85 C
o
o
o
o
o
o
PIN-
PACKAGE
10 TDFN-EP*
10 µMAX
12 UCSP
10 TDFN-EP*
10 µMAX
12 UCSP
TOP
MARK
ACM
—
—
ACI
—
—
Applications
Cellular Phones
PDAs
MP3 Players
Portable Audio
Block Diagram
V
DD
*EP = Exposed pad.
Ordering Information continued and Selector Guide appears
at end of data sheet.
Pin Configurations
DIFFERENTIAL
AUDIO INPUT
MODULATOR
AND H-BRIDGE
TOP VIEW
V
DD
1
IN+
2
3
4
5
10
PV
DD
9
OUT-
OUT+
PGND
SYNC
SYNC
INPUT
OSCILLATOR
IN-
GND
MAX9700
8
7
6
MAX9700
SHDN
TDFN/μMAX
UCSP is a trademark of Maxim Integrated Products, Inc.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Pin Configurations continued at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
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.
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
MAX9700
ABSOLUTE MAXIMUM RATINGS
V
DD
to 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
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
(V
DD
= PV
DD
= V
SHDN
= 3.3V,
V
GND
= V
PGND
= 0V, SYNC = GND (FFM), R
L
= 8Ω, R
L
connected between OUT+ and OUT-,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
GENERAL
Supply Voltage Range
Quiescent Current
Shutdown Current
Turn-On Time
Input Resistance
Input Bias Voltage
V
DD
I
DD
I
SHDN
t
ON
R
IN
V
BIAS
T
A
= +25°C
Either input
MAX9700A
Voltage Gain
A
V
MAX9700B
MAX9700C
MAX9700D
Output Offset Voltage
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
(Note 3)
Output Power
V
OS
CMRR
PSRR
T
A
= +25°C
T
MIN
≤
T
A
≤
T
MAX
f
IN
= 1kHz, input referred
V
DD
= 2.5V to 5.5V, T
A
= +25°C
200mV
P-P
ripple
THD+N = 1%
f
RIPPLE
= 217Hz
f
RIPPLE
= 20kHz
R
L
= 8Ω
R
L
= 6Ω
R
L
= 8Ω,
P
OUT
= 125mW
R
L
= 6Ω,
P
OUT
= 125mW
50
72
70
72
55
450
800
0.01
%
0.01
mW
dB
12
0.73
Inferred from PSRR test
2.5
4
0.1
30
20
0.83
6
12
15.6
20
±11
±80
±120
mV
dB
dB
0.93
5.5
5.2
10
V
mA
µA
ms
kΩ
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
P
OUT
Total Harmonic Distortion
Plus Noise
THD+N
f
IN
= 1kHz, either
FFM or SSM
2
_______________________________________________________________________________________
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
= V
SHDN
= 3.3V,
V
GND
= V
PGND
= 0V, SYNC = GND (FFM), R
L
= 8Ω, R
L
connected between OUT+ and OUT-,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
BW = 22Hz
to 22kHz
Signal-to-Noise Ratio
SNR
V
OUT
= 2V
RMS
A-weighted
SYNC = GND
Oscillator Frequency
f
OSC
SYNC = unconnected
SYNC = V
DD
(SSM mode)
SYNC Frequency Lock Range
Efficiency
DIGITAL INPUTS (SHDN, SYNC)
Input Thresholds
SHDN
Input Leakage Current
SYNC Input Current
V
IH
V
IL
2
0.8
±1
±5
V
µA
µA
η
P
OUT
= 500mW, f
IN
= 1kHz
800
94
FFM
SSM
FFM
SSM
980
1280
MIN
TYP
89
87
92
90
1100
1450
1220
±120
2000
kHz
%
1220
1620
kHz
dB
MAX
UNITS
MAX9700
ELECTRICAL CHARACTERISTICS
(V
DD
= PV
DD
= V
SHDN
= 5V,
V
GND
= V
PGND
= 0V, SYNC = GND (FFM), R
L
= 8Ω, R
L
connected between OUT+ and OUT-, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
Quiescent Current
Shutdown Current
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
SYMBOL
I
DD
I
SHDN
CMRR
PSRR
f = 1kHz, input referred
200mV
P-P
ripple
f = 217Hz
f = 20kHz
R
L
= 16Ω
Output Power
Total Harmonic Distortion
Plus Noise
P
OUT
THD+N = 1%
f = 1kHz, either
FFM or SSM
R
L
= 8Ω
R
L
= 6Ω
THD+N
R
L
= 8Ω, P
OUT
= 125mW
R
L
= 4Ω, P
OUT
= 125mW
FFM
SSM
FFM
SSM
CONDITIONS
MIN
TYP
5.2
0.1
72
72
55
700
1200
1600
0.015
0.02
92.5
90.5
95.5
93.5
dB
%
mW
MAX
UNITS
mA
µA
dB
dB
Signal-to-Noise Ratio
SNR
V
OUT
=
3V
RMS
BW = 22Hz to
22kHz
A-weighted
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 R
L
= 16Ω, L = 136µH.
Note 3:
PSRR is specified with the amplifier inputs connected to GND through C
IN
.
_______________________________________________________________________________________
3
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
MAX9700
Typical Operating Characteristics
(V
DD
= 3.3V, SYNC = GND (SSM), T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX9700 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX9700 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
V
DD
= +3.3V
R
L
= 8Ω
P
OUT
= 125mW
0.1
MAX9700 toc03
1
V
DD
= +5V
R
L
= 8Ω
1
V
DD
= +3.3V
R
L
= 8Ω
1
0.1
THD+N (%)
THD+N (%)
P
OUT
= 300mW
0.1
P
OUT
= 300mW
THD+N (%)
SSM MODE
0.01
P
OUT
= 125mW
0.01
P
OUT
= 125mW
0.01
FFM MODE
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9700 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9700 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT VOLTAGE
V
DD
= 5V
R
L
= 4Ω
10
MAX9700 toc06
100
V
DD
= 5V
R
L
= 8Ω
100
V
DD
= 5V
R
L
= 16Ω
10
100
10
THD+N (%)
THD+N (%)
THD+N (%)
1
f = 1kHz
0.1
f = 100Hz
1
1
f = 100Hz
0.1
f = 10kHz
0.1
0.01
f = 10kHz
0.01
f = 1kHz
f = 100Hz
0.001
0.01
f = 1kHz
0.001
0
0.2
0.4
0.6
0.8
1.0
0
0.5
1.0
1.5
2.0
f = 10kHz
0.001
0
0.5
1.0
OUTPUT POWER (W)
1.5
2.0
2.5
3.0
3.5
OUTPUT POWER (W)
OUTPUT POWER (W)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
V
DD
= 2.5V
R
L
= 8Ω
V
CM
= 1.25V
NO INPUT CAPACITORS
MAX9700 toc07
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX9700 toc08
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
V
DD
= 5V
f = 1kHz
R
L
= 8Ω
f
SYNC
= 1.4MHz
THD+N (%)
1
f
SYNC
= 800kHz
0.1
MAX9700 toc09
100
100
V
DD
= 5V
f = 1kHz
R
L
= 8Ω
FFM
(SYNC = GND)
SSM
0.1
100
10
10
10
THD+N (%)
THD+N (%)
1
DIFFERENTIAL
INPUT
1
0.1
0.01
0.001
0
0.1
0.2
SINGLE ENDED
0.01
FFM
(SYNC UNCONNECTED)
0.001
0.01
f
SYNC
= 2MHz
0.001
0
0.5
1.0
OUTPUT POWER (W)
1.5
2.0
0
0.5
1.0
OUTPUT POWER (W)
1.5
2.0
0.3
0.4
0.5
OUTPUT POWER (W)
4
_______________________________________________________________________________________
1.2W, Low-EMI, Filterless,
Class D Audio Amplifier
Typical Operating Characteristics (continued)
(V
DD
= 3.3V, SYNC = GND (SSM), T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. COMMON-MODE VOLTAGE
MAX9700 toc10
MAX9700
EFFICIENCY vs. OUTPUT POWER
MAX9700toc11
EFFICIENCY vs. OUTPUT POWER
90
80
EFFICIENCY (%)
70
60
50
40
30
20
R
L
= 4Ω
R
L
= 8Ω
MAX9700toc12
10
V
DD
= 3.3V
R
L
= 8Ω
f = 1kHz
P
OUT
= 300mW
DIFFERENTIAL INPUT
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
V
DD
= 3.3V
f = 1kHz
0
0.3
0.6
0.9
1.2
R
L
= 8Ω
R
L
= 4Ω
100
THD+N (%)
1
0.1
10
0
1.5
0
0.5
1.0
1.5
2.0
V
DD
= 5V
f = 1kHz
2.5
3.0
0.01
0
0.5
1.0
1.5
2.0
2.5
3.0
COMMON-MODE VOLTAGE (V)
0
OUTPUT POWER (W)
OUTPUT POWER (W)
EFFICIENCY vs. SUPPLY VOLTAGE
MAX9700 toc13
EFFICIENCY
vs. SYNC INPUT FREQUENCY
MAx9700 toc14
OUTPUT POWER vs.
SUPPLY VOLTAGE
f = 1kHz
R
L
= 4Ω
THD+N = 10%
R
L
= 4Ω
THD+N = 1%
R
L
= 8Ω
THD+N = 10%
MAX9700toc15
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
2.5
3.0
3.5
f = 1kHz
P
OUT
= MAX (THD+N = 1%)
4.0
4.5
5.0
R
L
= 4Ω
R
L
= 8Ω
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
V
DD
= 3.3V
f = 1kHz
P
OUT
= 300mW
R
L
= 8Ω
800
1000
1200
1400
1600
1800
3.5
3.0
OUTPUT POWER (W)
2.5
2.0
1.5
1.0
0.5
0
R
L
= 8Ω
THD+N = 1%
2.5
3.0
3.5
4.0
4.5
5.0
5.5
5.5
2000
SUPPLY VOLTAGE (V)
SYNC FREQUENCY (kHz)
SUPPLY VOLTAGE (V)
OUTPUT POWER vs. LOAD RESISTANCE
MAX9700toc16
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
MAX9700TOC17
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-10
-20
-30
PSRR (dB)
-40
-50
-60
-70
-80
-90
-100
OUTPUT REFERRED
INPUTS AC GROUNDED
V
DD
= 3.3V
MAX9700TOC18
2000
f = 1kHz
THD+N = 1%
1600
OUTPUT POWER (mW)
V
DD
= 5V
0
-10
-20
-30
CMRR (dB)
-40
-50
-60
-70
-80
-90
INPUT REFERRED
V
IN
= 200mV
P-P
0
1200
800
V
DD
= 3.3V
400
0
0
10 20 30 40 50 60 70 80 90 100
LOAD RESISTANCE (Ω)
-100
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
_______________________________________________________________________________________
5
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