19-3678; Rev 3; 4/13

MAX9708

20W/40W, Filterless, Spread-Spectrum,

Mono/Stereo, Class D Amplifier

EVALUATION KIT AVAILABLE

For pricing, delivery, and ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

General Description

The MAX9708 mono/stereo, Class D audio power amplifi-

er delivers up to 2 x 21W into an 8

Ω stereo mode and

1 x 42W into a 4

Ω load in mono mode while offering up to

87% efficiency. The MAX9708 provides Class AB amplifi-

er performance with the benefits of Class D efficiency,

eliminating the need for a bulky heatsink and conserving

power. The MAX9708 operates from a single +10V to

+18V supply, driving the load in a BTL configuration.

The MAX9708 offers two modulation schemes: a fixed-

frequency modulation (FFM) mode, and a spread-spec-

trum

modulation

(SSM)

mode

that

reduces

EMI-radiated emissions. The MAX9708 can be synchro-

nized to an external clock from 600kHz to 1.2MHz. A

synchronized output allows multiple units to be cascad-

ed in the system.

Features include fully differential inputs, comprehensive

click-and-pop suppression, and four selectable-gain set-

tings (22dB, 25dB, 29.5dB, and 36dB). A pin-program-

mable thermal flag provides seven different thermal

warning thresholds. Short-circuit and thermal-overload

protection prevent the device from being damaged

during a fault condition.

The MAX9708 is available in a 56-pin TQFN (8mm x

8mm x 0.8mm) package and is specified over the

extended -40°C to +85°C temperature range.

Applications

LCD TVs

PDP TVs

Automotive

PC/HiFi Audio Solutions

Features

o 2 x 21W Output Power in Stereo Mode

(8

Ω, THD = 10%)

o 1 x 42W Output Power in Mono Mode

(4

Ω, THD = 10%)

o High Efficiency: Up to 87%

o Filterless Class D Amplifier

o Unique Spread-Spectrum Mode

o Programmable Gain (+22dB, +25dB, +29.5dB,

+36dB)

o High PSRR (90dB at 1kHz)

o Differential Inputs Suppress Common-Mode

Noise

o Shutdown and Mute Control

o Integrated Click-and-Pop Suppression

o Low 0.1% THD+N

o Current Limit and Thermal Protection

o Programmable Thermal Flag

o SYNC Input/Output

o Available in Thermally Efficient, Space-Saving

56-Pin TQFN Package

CLASS D

MODULATOR

SYNCOUT

TEMP

OUTPUT

PROTECTION

GAIN

CONTROL

FS1, FS2

MAX9708

STEREO MODE

G1, G2

2

SYNC

RIGHT

CHANNEL

LEFT

CHANNEL

MONO

2

TH0, TH1,

TH2

3

PART

TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX9708ETN+

-40°C to +85°C

56 TQFN-EP*

T5688-3

MAX9708ETN/V+ -40°C to +85°C

56 TQFN-EP*

T5688-3

Simplified Block Diagram

Ordering Information

+

Denotes lead-free package.

/V denotes an automotive qualified part.

*

EP = Exposed pad.

Pin Configurations appear at end of data sheet.

CLASS D

MODULATOR

SYNCOUT

TEMP

OUTPUT

PROTECTION

GAIN

CONTROL

FS1, FS2

MAX9708

MONO MODE

G1, G2

2

SYNC

AUDIO

INPUT

VDIGITAL

MONO

2

TH0, TH1,

TH2

3