WM8731: CODEC with headphone driver


The WM8731 or WM8731L (WM8731/L) are low power stereo CODECs with an integrated headphone driver. The WM8731/L is designed specifically for portable MP3 audio and speech players and recorders. The WM8731 is also ideal for MD, CD-RW machines and DAT recorders. 

Stereo line and mono microphone level audio inputs are provided, along with a mute function, programmable line level volume control and a bias voltage output suitable for an electret type microphone. 

Stereo 24-bit multi-bit sigma delta ADCs and DACs are used with oversampling digital interpolation and decimation filters. Digital audio input word lengths from 16-32 bits and sampling rates from 8kHz to 96kHz are supported. 

Stereo audio outputs are buffered for driving headphones from a programmable volume control, line level outputs are also provided along with anti-thump mute and power up/down circuitry. 

The device is controlled via a 2 or 3 wire serial interface. The interface provides access to all features including volume controls, mutes, de-emphasis and extensive power management facilities. The device is available in a small 28-lead SSOP package or the smaller 28 lead quad flat leadless package (QFN).


  • Stereo Audio Codec with Integrated Headphone Driver (50mW on 16W @ 3.3V)
  • 1.42 – 3.6V Digital Supply
  • 2.7 – 3.6V Analogue Supply (standard)
  • 1.8 – 3.6V Analogue Supply (’L’ version)
  • Playback Mode Power Consumption < 18mW
  • 100dB SNR (‘A’ weighted @ 48kHz) DAC
  • 90dB SNR (‘A’ weighted @ 48kHz) ADC
  • Sampling Frequency: 8kHz – 96kHz
  • Master or Slave Clocking Mode
  • USB clocking mode can generate all common MP3 sample rates (incl. 441.kHz) directly from USB clock
  • Output Volume and Mute Controls
  • Microphone Input and Electret Bias with Side Tone Mixer
  • Selectable ADC High Pass Filter
  • 2 or 3-Wire MPU Serial Control Interface
  • Programmable Audio Data Interface Modes
  • 28-Pin SSOP Package