Power efficiency in mobile audio headphone applications

March 08, 2011

Power efficiency in mobile audio headphone applications

Paul Giletti

A key for the success of mobile audio resides in power consumption reduction, as the battery must handle more applications and last a longer time. Regarding the analog audio, referred to as the audio CODEC where specifications mainly focus on the stereo playback mode, quiescent power consumption largely felt under 10 mW, rising headphone driver power consumption as a major concern. In addition to the quiescent power benchmark that does not reflect actual usage case, the power efficiency helps to gauge dynamic power consumption and its significant contribution to the total power consumption bill. The need for low power solution even brings back from the old audio systems the class G architecture and its class H twin brother.
This article will review and discuss these different classes of amplifiers to better understand and calculate power dissipation. Then, low power operation will lead to regulation problematic, audio signal characteristics and system complexity.

Part-1: class AB, G and H: principle
Part-2: Amplifier efficiency calculation
Part-3: Audio output power delivered by the headphone
Part-4: (Power supply) Regulation puzzle
Part-5: System considerations

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