Rainbow Electronics 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 patented, 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 ✕ 3mm ✕ 0.8mm)
10-Pin µMAX
12-Bump UCSP (1.5mm ✕2mm ✕0.6mm)

MAX9700

1.2W, Low-EMI, Filterless,
Class D Audio Amplifier

________________________________________________________________ Maxim Integrated Products 1

Pin Configurations

Ordering Information

MAX9700

DIFFERENTIAL

AUDIO INPUT

SYNC

INPUT

V

DD

OSCILLATOR

MODULATOR

AND H-BRIDGE

Block Diagram

19-3030; Rev 0; 10/03

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

Pin Configurations continued at end of data sheet.

Ordering Information continued at end of data sheet.

*Future Product—contact factory for availability.

UCSP is a trademark of Maxim Integrated Products, Inc.

Selector Guide appears at end of data sheet.

PART TEMP RANGE

o

MAX9700AETB* -40

MAX9700AEUB* -40oC to +85oC 10 µMAX —

MAX9700AEBC-T* -40oC to +85oC 12 UCSP-12 —

MAX9700BETB -40oC to +85oC 10 TDFN ACI

MAX9700BEUB* -40oC to +85oC 10 µMAX —

MAX9700BEBC-T* -40oC to +85oC 12 UCSP-12 —

C to +85oC 10 TDFN ACM

PIN­PACKAGE

TOP

MARK

TOP VIEW

V

1

DD

IN+

2

IN-

MAX9700

3

4

5

TDFN/µMAX

10

PV

DD

OUT-

9

OUT+

8

PGNDGND

7

SYNCSHDN

6

1.2W, Low-EMI, Filterless,
Class D Audio Amplifier

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDD= PVDD= SHDN = 3.3V, GND = PGND = 0V, SYNC = GND (FFM), RL= 8Ω, RLconnected between OUT+ and OUT-

(MAX9700B), 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

GENERAL

Supply Voltage Range V

Quiescent Current I

Shutdown Current I

Turn-On Time t

Input Resistance R

Input Bias Voltage V

Voltage Gain A

Output Offset Voltage V

Common-Mode Rejection Ratio CMRR fIN = 1kHz, input referred 72 dB

Power-Supply Rejection Ratio
(Note 3)

Output Power P

Total Harmonic Distortion
Plus Noise

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DD

DD

SHDN

ON

BIAS

OS

PSRR

OUT

THD+N

Inferred from PSRR test 2.5 5.5 V

TA = +25°C1420kΩ

IN

Either input 0.73 0.83 0.93 V

MAX9700A 6

MAX9700B 12

V

MAX9700C 15.6

MAX9700D 20

TA = +25°C ±11 40

T

≤ TA ≤ T

MIN

VDD = 2.5V to 5.5V 50 70

200mV

THD+N = 1%

f

= 1kHz, either

IN

FFM or SSM

P-P

MAX

ripple

f

= 217Hz 72

RIPPLE

= 20kHz 55

f

RIPPLE

RL = 8Ω 600

= 6Ω 800

R

L

RL = 8Ω,
P

= 125mW

OUT

R

= 6Ω,

L

P

= 125mW

OUT

4 5.2 mA

0.1 5 µA

30 ms

±65

0.01

0.01

dB

mV

dB

mW

%

MAX9700

1.2W, Low-EMI, Filterless,
Class D Audio Amplifier

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VDD= PVDD= SHDN = 3.3V, GND = PGND = 0V, SYNC = GND (FFM), RL= 8Ω, RLconnected between OUT+ and OUT-

(MAX9700B), 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 +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

= 6Ω, L = 47µH.

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

.

ELECTRICAL CHARACTERISTICS

(VDD= PVDD= SHDN = 5V, GND = PGND = 0V, SYNC = GND (FFM), RL= 8Ω, RLconnected between OUT+ and OUT-

(MAX9700B), T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Notes 1, 2)

Signal-to-Noise Ratio SNR V

Oscillator Frequency f

SYNC Frequency Lock Range 800 2000 kHz

Efficiency η P

DIGITAL INPUTS (SHDN, SYNC)

Input Thresholds

SHDN Input Leakage Current ±1µA

SYNC Input Current ±5µA

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

FFM 89

SSM 87

FFM 92

SSM 90

OSC

BW = 22Hz

= 2V

OUT

SYNC = GND 980 1100 1220

SYNC = float 1280 1450 1620

SYNC = VDD (SSM mode)

OUT

V

IH

V

IL

RMS

= 500mW, fIN = 1kHz 94 %

to 22kHz

A-weighted

dB

1220
±120

2

0.8

kHz

V

Quiescent Current I

Shutdown Current I

Common-Mode Rejection Ratio CMRR f = 1kHz, input referred 72 dB

Power-Supply Rejection Ratio PSRR 200mV

Total Harmonic Distortion
Plus Noise

Signal-to-Noise Ratio SNR

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DD

SHDN

f = 217Hz 72

f = 20kHz 55

RL = 16Ω 700

RL = 8Ω 1200Output Power P

= 6Ω 1600

R

L

RL = 8Ω, P

R

= 4Ω, P

L

BW = 22Hz to
22kHz

A-weighted

= 125mW 0.015

OUT

= 125mW 0.02

OUT

FFM 92.5

SSM 90.5

FFM 95.5

SSM 93.5

OUT

THD+N

ripple

P-P

THD+N = 1%

f = 1kHz, either
FFM or SSM

V

=

OUT

3V

RMS

5.2 mA

0.1 µA

dB

mW

%

dB

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 POWER

MAX9700 toc06

OUTPUT POWER (W)

THD+N (%)

VDD = 5V
R

L

= 6Ω

f = 1kHz

f = 10kHz

f = 100Hz

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 FLOATING)

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 (%)

VDD = +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 (%)

VDD = +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

1.2W, Low-EMI, Filterless,
Class D Audio Amplifier

_______________________________________________________________________________________ 5

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 (%)

0.80.60.40.2

10

20

30

40

50

60

70

80

90

100

0

0 1.0

RL = 6Ω

RL = 8Ω

VDD = 3.3V
f = 1kHz

EFFICIENCY vs. OUTPUT POWER

MAX9700toc12

OUTPUT POWER (W)

EFFICIENCY (%)

1.51.00.5

10

20

30

40

50

60

70

80

90

100

0

0 2.0

RL = 6Ω

RL = 8Ω

VDD = 5V
f = 1kHz

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

RL = 6Ω

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 (mW)

5.04.54.03.53.0

500

1000

1500

2000

2500

0

2.5 5.5

RL = 6Ω
THD+N = 1%

f = 1kHz

RL = 6Ω
THD+N = 10%

RL = 8Ω
THD+N = 10%

RL = 8Ω
THD+N = 1%

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

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 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VDD= 3.3V, SYNC = GND (SSM), TA= +25°C, unless otherwise noted.)

GSM POWER-SUPPLY REJECTION

V

DD

MAX9700 toc19

500mV/div

MAX9712

OUTPUT

f = 217Hz
INPUT LOW = 3V
INPUT HIGH = 3.5V

2ms/div

DUTY CYCLE = 88%

= 8Ω

R

L

100µV/div

OUTPUT FREQUENCY SPECTRUM

0

FFM MODE

= -60dBV

V

OUT

-20
f = 1kHz

= 8Ω

R

L

-40
UNWEIGHTED

-60

-80

-100

OUTPUT MAGNITUDE (dBV)

-120

-140
0 5 10 15 20

FREQUENCY (kHz)

MAX9700 toc20

OUTPUT FREQUENCY SPECTRUM

0

SSM MODE

= -60dBV

V

OUT

-20
f = 1kHz

= 8Ω

R

L

-40
UNWEIGHTED

-60

-80

-100

OUTPUT MAGNITUDE (dBV)

-120

-140
0 5 10 15 20

FREQUENCY (kHz)

WIDEBAND OUTPUT SPECTRUM

0

-10

-20

-30

-40

-50

-60

-70

OUTPUT AMPLITUDE (dB)

-80

-90

-100
1M 10M 100M 1G

(SSM MODE)

FREQUENCY (Hz)

MAX9700 toc21

-20

-40

-60

-80

-100

OUTPUT MAGNITUDE (dBV)

-120

-140

RBW = 10kHz

OUTPUT FREQUENCY SPECTRUM

0

SSM MODE

= -60dBV

V

OUT

f = 1kHz

= 8Ω

R

L

A-WEIGHTED

0 5 10 15 20

MAX9700 toc24

FREQUENCY (kHz)

SHDN

MAX9712

OUTPUT

WIDEBAND OUTPUT SPECTRUM

0

-10

MAX9700 toc22

-20

-30

-40

-50

-60

-70

OUTPUT AMPLITUDE (dB)

-80

-90

-100
1M 10M 100M 1G

TURN-ON/TURN-OFF RESPONSE

f = 1kHz

= 8Ω

R

L

10ms/div

(FFM MODE)

RBW = 10kHz

MAX9700 toc23

FREQUENCY (Hz)

3V

MAX9700 toc25

0V

250mV/div