Rajendra Turakani and Krishna Kumar, Ittiam Systems
Jan 02, 2006 (5:00 AM), CommsDesign
A key measurement in a portable media player (PMP) is the time duration that it can play multimedia content from a fully charged battery (Fig. 1). With the available board area decreasing considerably and feature set increasing rapidly, designers must implement systematic power optimization strategies in both hardware and software to maximize battery life.
Saving 10 mA of current on a media player (with typical current consumption of 450 mA) while deriving power from 1800-mAh battery could increase run time by 6 min. The same figures for an audio only player (without hard disk and the full-function display replaced with a 225-mA graphic LCD) would be 22 min.
The first step in power optimization is power characterization, which helps the designer implement the strategies in an effective, methodical way (Fig. 2). For example, the hard disk uses a mechanical motor. Hence, it consumes lot of power. The latest hard disks come with many power optimization options, including different modes in which the disk can be operated, each having its own power requirement (see the table).
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