0.5 V Start-Up 87% Ef ficiency 0.75 mm² On-Chip Feed-Forward Single-Inductor Dual-Output (SIDO) Boost DC-DC Converter for Battery and Solar Cell Operation Sensor Network Micro-Computer Integration Y asunobu Nakase, Shinichi Hirose, Hiroshi Onoda, Y asuhiro Ido, Y oshiaki Shimizu, Tsukasa Oishi

Abstract

An on-chip low power single-inductor dual-output (SIDO) DC-DC boost converter is proposed for battery and solar cell operating sensor network applications. A proposed feed forward control determines the Ton/Toff ratio precisely for each output without any compensation or linear capacitor. This feature helps reduce the costs of the external components and utilize an inexpensive process technology. A test chip was fabricated by 190-nm flash-memory embedded micro-computers CMOS process technology and can achieve an ef ficiency of 87% with a small area size of just 0.75 mm². For solar cell operation, a 0.5 V start-up was achieved even with a high threshold voltage of 0.7 V with a proposed forward back biased c harge pump. A constant voltage algorithm was implemented as a maximum power point tracking (MPPT) control. With this MPPT control, a solar cell with an open voltage of 1.03 V and a short current of 83 mA was able to charge a super capacitor of 0.4 F up to 5 V within 80 s.