High efficiency two-phase switched-capacitor converter with seven distinct negative voltage ratios for power saving applications

摘要

In this letter, a reconfigured switched-capacitor converter (SCC) is proposed that is capable of achieving seven negative voltage conversion ratios (VCRs) using only three flying capacitors and minimum number of switches. The proposed converter is used to drive a white-LED backlight (WLB) in cellular phones for various backlight conditions. The negative VCR is realized with a single-input single-output structure using 10 CMOS switches and three flying capacitors. The reconfigured SCC has an advantage of choosing buck/boost voltages to drive the WLBs for various black light conditions. The proposed converter is tested experimentally with a low input voltage of 10 mV to 0.5 mV, and it maintains a high efficiency of 85%-95% with an output voltage that varies from -1 mV to -0.1 V.