A multi-modes charge-pump based high efficiency wide input range DC-DC converter

Abstract

A high efficiency charge-pump based wide input range DC-DC converter is proposed. The first stage is a multi-modes charge-pump and the second stage is a synchronous buck converter. The charge-pump is unregulated and adaptively switches between 1x, 0.5x, and 0.33x modes according to input voltage. It does the rough voltage conversion while buck converter does the fine voltage regulation. As they exhibit different efficiency tendency within the same input range, the total efficiency can get improved by combining them, especially at high input voltage. Detailed theoretical efficiency analysis and comparison between multi-modes charge-pump and synchronous Buck are given in this paper. The control benefits brought by the two-stage solution of wide input range DC-DC converter are also analyzed. A 10 W prototype is built to verify the benefits of proposed solution. Experiment results show that the highest efficiency improvement is 7% at heavy load and 16% at light load.