WM8904 extends playback time in portable devices

Wolfson Microelectronics has introduced the WM8904, an ultra low-power Codec with Class W headphone and line drivers.

The WM8904 consumes a small amount of power and significantly extends playback time in portable applications, such as media players, headsets, voice recorders and multimedia phones.

The WM8904 is part of Wolfson's range of next-generation ultra low-power audio devices.

It delivers high performance audio in an ultra slim, low-profile form factor.

The WM8904 features Wolfson's Class W amplifier technology, which intelligently tracks the actual music signal level and uses an adaptive dual-drive charge pump to optimise power dissipation.

The ground-referenced output also eliminates the need for large DC-blocking headphone capacitors, resulting in improved bass response and significant savings in PCB space and the audio subsystem bill of materials (BOM).

The WM8904 also features Wolfson's SmartDACtechnology, a low-power DAC capacitor switching architecture that enables DAC-to-headphone power consumption of just 4mW and delivers up to 30mW per channel into a headphone load.

Audio performance is significantly enhanced with the integration of Wolfson's innovative Silentswitchtechnology, which extends its 'pop and click' suppression capability by incorporating sophisticated clamp and sequencer circuitry.

With this feature, unwanted noise at the headphone and line outputs is reduced during power-up/down and mute/un-mute by clamping the output to ground.

Using an integrated control write sequencer - with programmable delay times - to power-up and power-down parts of the WM8904 further reduces 'pops and clicks' and reduces time to market by lowering software-driver development time.

The WM8904 incorporates an advanced dynamic range controller (DRC), which enhances audio performance.

When in record mode, the DRC can be flexibly configured to optimise recorded sound quality, preventing distortion while maximising the recorded signal.

Wolfson has also implemented a 'quick release' feature that enhances the intelligibility of recorded sound in the presence of loud impulse noises.

This feature ensures that noisy events such as user handling do not mask the recorded signal.

In playback mode, the DRC maximises the volume of the output signal, boosting the perceived loudness of the audio data.

Wolfson's Retune Mobile parametric equaliser is a powerful feature that enables system designers to accurately customise the output signal path to optimise the performance of the speaker or other transducer.

Line inputs, along with digital and analogue microphone inputs, are all supported, with bypass paths to the class W headphone and line outputs.

The WM8904 is available in two compact-package options, including an ultra-small 2.6 x 2.5mm CSP.

The WM8904 delivers an optimal combination of audio performance, power consumption, package size and total solution cost, making it ideal for a wide range of portable multimedia applications.

It is available for sampling now in a 32-lead 4 x 4mm QFN, 36-ball CSP package.

WM8904 customer evaluation boards with the Wolfson Interactive Setup and Configuration Environment (WISCE) are available to aid device evaluation and development.

WISCE connects to the evaluation board over USB and offers a unique interactive register map interface.

This interface provides unprecedented control and overview of the device settings.

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