1.8W, Filterless, Ultra-Low EMI, Stereo Class D Audio Power Amplifier

1.8W Ultra-Low EMI Stereo Amplifier that Passes FCC Radiation Emissions Standards

Please check latest availability status for a specific part variant.


The MAX9773 3rd-generation, ultra-low EMI, stereo, Class D audio power amplifier provides Class AB performance with Class D efficiency. The MAX9773 delivers 1.8W per channel into a 4Ω load, and offers efficiencies above 90%. Active emissions limiting (AEL) circuitry greatly reduces EMI by actively controlling the output FET gate transitions under all possible transient conditions. AEL controls high-frequency emissions resulting from conventional Class D free-wheeling behavior in the presence of an inductive load. Zero-dead- time (ZDT) technology maintains state-of-the-art efficiency and THD+N performance by allowing the output FETs to switch simultaneously without cross conduction. A spread-spectrum modulation scheme eliminates the need for output filtering found in traditional Class D devices. These design concepts reduce component count and extend battery life.

The MAX9773 offers two modulation schemes: a fixed-frequency (FFM) mode, and a spread-spectrum (SSM) mode that reduces EMI-radiated emissions. The MAX9773 oscillator can be synchronized to an external clock through the SYNC input, allowing synchronization of multiple Maxim Class D amplifiers. The sync output (SYNC_OUT) can be used for a master-slave application where more channels are required. The MAX9773 features a fully differential architecture, a full bridge-tied load (BTL) output, and comprehensive click-and-pop suppression. The device features internally set gains of 12dB, 15.6dB, 20dB, and 26dB selected through two gain-select inputs, further reducing external component count.

The MAX9773 features high 80dB PSRR, less than 0.1% THD+N, and SNR in excess of 88dB. Short-circuit and thermal-overload protection prevent the device from being damaged during a fault condition. The MAX9773 is available in 24-pin thin QFN-EP (4mm x 4mm x 0.8mm), and 20-bump UCSP™ (2mm x 2.5mm x 0.6mm) packages. The MAX9773 is specified over the extended -40°C to +85°C temperature range.
MAX9773: Block Diagram MAX9773: Block Diagram Enlarge+

Key Features

  • Filterless Amplifier Passes FCC-Radiation Emissions Standards with 6in of Cable
  • Unique Spread-Spectrum Mode and Active Emissions Limiting Achieves Better than 15dB Margin Under FCC Limit
  • Zero Dead Time (ZDT) H-Bridge Maintains Good THD+N Performance
  • Single-Supply Operation (2.5V to 5.5V)
  • Stereo Output (4Ω, VDD = 5V, THD+N = 1%, POUT = 1.8W)
  • No LC Output Filter Required
  • 85% Efficiency (RL = 8Ω, POUT = 600mW)
  • Less Than 0.1% THD+N
  • High 80dB PSRR
  • Fully Differential Inputs
  • Integrated Click-and-Pop Suppression
  • Low-Power Shutdown Mode (0.1µA)
  • Short-Circuit and Thermal-Overload Protection
  • Pin-for-Pin Compatible with the MAX9701
  • Available in Thermally Efficient, Space-Saving Packages
    • 24-Pin TQFN-EP (4mm x 4mm x 0.8mm)
    • 20-Bump UCSP (2mm x 2.5mm x 0.6mm)


  • Cellular/Multimedia Phones
  • Handheld Gaming Consoles
  • MP3 Players
  • Notebooks

Technical Documents

App Note 3924 Thermal Considerations for a UCSP Package

Quality and Environmental Data

Request Reliability Report for: MAX9773 
Lead-Free Package Tin (Sn) Whisker Reports
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 >


Related Resources

Boosted Class-D Amplifier with Integrated Dynamic Speaker Management

  • Integrated Speaker Current and Voltage Sense Requires no External Components
  • Integrated Programmable 10V Boost Converter
  • Integrated Dynamic Speaker Management

PDF Title