20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier

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The MAX9708 mono/stereo, Class D audio power amplifier delivers up to 2 x 21W into an 8Ω stereo mode and 1 x 42W into a 4Ω load in mono mode while offering up to 87% efficiency. The MAX9708 provides Class AB amplifier 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-spectrum modulation (SSM) mode that reduces EMI-radiated emissions. The MAX9708 can be synchronized to an external clock from 600kHz to 1.2MHz. A synchronized output allows multiple units to be cascaded in the system.

Features include fully differential inputs, comprehensive click-and-pop suppression, and four selectable-gain settings (22dB, 25dB, 29.5dB, and 36dB). A pin-programmable 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.
MAX9708: Simplified Block Diagram MAX9708: Simplified Block Diagram Enlarge+

Key Features

  • 2 x 21W Output Power in Stereo Mode (8Ω, THD = 10%)
  • 1 x 42W Output Power in Mono Mode (4Ω, THD = 10%)
  • High Efficiency: Up to 87%
  • Filterless Class D Amplifier
  • Unique Spread-Spectrum Mode
  • Programmable Gain (+22dB, +25dB, +29.5dB, +36dB)
  • High PSRR (90dB at 1kHz)
  • Differential Inputs Suppress Common-Mode Noise
  • Shutdown and Mute Control
  • Integrated Click-and-Pop Suppression
  • Low 0.1% THD+N
  • Current Limit and Thermal Protection
  • Programmable Thermal Flag
  • SYNC Input/Output
  • Available in Thermally Efficient, Space-Saving 56-Pin TQFN Package


  • Automotive
  • LCD TVs
  • PC/HiFi Audio Solutions
  • PDP TVs
Part NumberClassSpkr. Amp. VCC
Spkr. Amp. VCC
Spkr. Amp. ICC
POUT into 4Ω @ 1% THD+N
POUT into 4Ω @ 10% THD+N
POUT into 8Ω @ 1% THD+N
POUT into 8Ω @ 10% THD+N
Spkr. Amp. Half Pwr. THD+N
minmaxtypminminminminA- WeightedminSee Notes
MAX9708 D101820324216210.159590
$3.44 @1k
See All Speaker Amplifiers (33)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX9708EVKIT: Evaluation Kit for the MAX9708

Technical Documents

App Note 3977 Class D Amplifiers: Fundamentals of Operation and Recent Developments
App Note 425

Quality and Environmental Data

Product Reliability Reports: MAX9708.pdf 
Lead-Free Package Tin (Sn) Whisker Reports

CAD Symbols and Footprints

  • MAX9708ETN+D
  • MAX9708ETN+TD
  • Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

    Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

    Quality Management System >
    Environmental Management System >


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