Current portable device demands not only higher performance but also lower power consumption. For the reason, this paper describes a low power System-on-Chip (SoC) architecture that targets playback multimedia format. To significantly reduce power consumption of the SoC, the system exploits a DSP core to decode compressed audio. It is key technique that a pre-buffer keeps compressed audio data. Therefore, the DSP can independently playback audio data, and other system including CPU and DRAM is able to be power off until all audio data remaining in the pre-buffer is exhausted by the DSP. For seamless operation, we designed new kernel driver which controls the DSP and CPU and it is embedded into Linux kernel sets of the Google’s Android 2.2. Energy efficiency is evaluated by using fourteen audio sequences encoded with mp3 of which format is 128kbps stereo. The experimental results show that the proposed system required only 25% power of the conventional DVFS algorithm and guaranteed Quality of Service (QoS) for mp3 playing.
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