Codec extends battery life
13 February 2008
Barcelona : Wolfson Microelectronics has developed an ultra-low power audio codec with class g, ground-referenced headphone driver.
At this year's Mobile World Congress, the company claims that the WM900 extends battery life in portable media players and multimedia handsets.
The WM8900’s quiescent headphone playback power consumption is under 6mW in voice mode and under 11mW in hi-fi mode, described as ideal for extending battery life in portable audio applications. It also betters the quiescent power consumption, claims the company, of many feature-rich multimedia codecs with ground referenced headphone outputs by up to 25 per cent. When using a typical 300mAH battery, device can extend battery life by up to 11 hours during headphone music playback at a typical 2mW/channel listening level.
The ground referenced headphone outputs remove the need for bulky DC blocking capacitors, reducing the device size to a low profile 0.55mm high 40pin QFN package.
The class G architecture is implemented by powering the headphone amplifier with a dual input, level shifting, intelligent charge pump. The pump generates positive and negative power supply rails, ground referencing the headphone outputs. Automatic control of the charge pump maintains the most power-efficient operating state during headphone playback without operator intervention or host software.
The headphone amplifier also eliminates many sources of pops and clicks during power-up, power-down, mute and unmute to deliver a high audio performance.
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