WM8903: Ultra low power CODEC for portable audio applications
The WM8903 is a high performance ultra-low power stereo CODEC optimised for portable audio applications.
The device features stereo ground-referenced headphone amplifiers using the Wolfson ‘Class-W’ amplifier techniques - incorporating an innovative dual-mode charge pump architecture - to optimise efficiency and power consumption during playback. The ground-referenced outputs eliminate headphone coupling capacitors. Both headphone and line outputs include common mode feedback paths to reject ground noise.
Control sequences for audio path setup can be pre-loaded and executed by an integrated sequencer to reduce software driver development and eliminate pops and clicks via Wolfson’s SilentSwitch™ technology.
The analogue input stage can be configured for single ended, pseudo-differential or fully differential inputs. Up to 3 stereo microphone or line inputs may be connected. The input impedance is constant with PGA gain setting.
A stereo digital microphone interface is provided, which can also be mixed with the mic/line signals at the output mixers.
A dynamic range controller provides compression and level control to support a wide range of portable recording applications. Anti-clip and quick release features offer good performance in the presence of loud impulsive noises.
Common audio sampling frequencies are supported from a range of external clocks, including 3MHz, 12MHz or 24MHz.
The WM8903 can operate directly from a single 1.8V switched supply. For optimal power consumption, the digital core can be operated from a 1.0V supply.
- 4.5mW power consumption for DAC to headphone playback
- DAC SNR 96dB typical, THD -86dB typical
- ADC SNR 92dB typical, THD -80dB typical
- Control sequencer for pop-free start-up and shut-down
- Single register write for default start-up sequence
- Stereo digital microphone input
- 3 single ended inputs per stereo channel
- 2 pseudo differential inputs per stereo channel
- 1 fully differential mic input per stereo channel
- Digital Dynamic Range Controller (compressor / limiter)
- Digital sidetone mixing
- Ground-referenced headphone driver
- Ground-referenced line outputs
- Stereo differential line driver for direct interface to WM9001 speaker driver
- 40-pin 5x5mm QFN package
Ordering & Samples
- Impedance Compensation (Zobel Network) for Ground Referenced Outputs
- External Component Requirements for Ground Referenced Outputs
- DRC Operation in Wolfson Audio CODECs, Rev 1.0
- Improving the PSRR in Wolfson CODECs
- WM8903 ECM Microphone Detection using MICBIAS Current
- I2S USB Audio Streaming, Rev 1.0
- DRC Attack and Decay Times for Real Audio Signals, Rev 1.0
- Wolfson Control Write Sequencer, Rev 1.0
- Decoupling and Layout Methodology for Wolfson DACs, ADCs and CODECs, Rev 1.1