Increasing sleep-mode efficiency by reducing battery current using a DC-DC converter

Abstract

Battery current is a key parameter that decides the runtime of a portable electronic system. For low power applications like IEEE 802.15.4 and Zigbee wireless network, the average battery current drain approximates the sleep mode current drain, since significantly more time is spent in sleep than in active usage. This paper proposes substituting a DC-DC converter for a low drop-out (LDO) regulator in the sleep mode power chain, such that the current drawn from the battery would be less than the actual current drained by the load. The battery current saving, and hence battery runtime extension, is estimated to be around 35% based on the analysis of a 65 nm CMOS IEEE 802.15.4/Zigbee low power wireless system-on-chip (SoC) model, whose parameters are extracted from state-of-theart industrial products and experimental data from advanced nanometer processes.

Sleep power minimisation using adaptive duty‐cycling of DC–DC converters in state‐retentive systems

“…Battery-operated IEEE 802.15.4 sensor nodes are usually in sleep mode for almost 99% of the time when used in typical WSN applications, waking up periodically for a few milliseconds to check sensors or polling the radio interface [9]. Unfortunately, sleep power cannot be reduced to zero by switching OFF the power supply without state loss or expensive copies into non-volatile memory (NVM), which can affect the long-term dependability of the system because of the limited number of erase-write cycles of NVM.…”