Power-efficient series-charge parallel-discharge charge pump circuit for LED drive

A charge pump drive circuit for LED lighting is proposed. This circuit is realized with repeated use of a compact unit module consisted of a capacitor and diodes. The series-charge and parallel-discharge operation gives the efficiency better than the conventional converters with ac line input. This paper also shows how to minimize the number of modules for a given number of LEDs. A prototype implemented the charge pump drive circuit shows a maximum efficiency of 95% for 22 LEDs in series with the ac line voltage of 220 Vrms.