A study on battery life tradeoff between deep sleep and sleep modes of an actual PDA

Extending the battery life time for battery-powered devices has become a critical issue for portable system designers. This paper presents a comprehensive study of sleep and deep sleep modes on power consumption of an actual PDA. Our work is based on the concept that the effect use of each componentpsilas power saving mode can significantly reduce total power consumption in a PDA. In our experiments, we measured the current of each power rail of a real PDA to explore how much power is consumed by each power rail for the different modes. We measured the total power for playing a WMV file as well as for idle and system off modes. The results of this study show that a system CPU can save 16.9% in battery life by switching to deep sleep mode rather than sleep mode. With the understanding provided by this analysis, designers can extend battery life time by better managing the fixed amount of energy provided by the battery.