A Multiphase Buck Converter With a Rotating Phase-Shedding Scheme For Efficient Light-Load Control

Abstract

Mobile devices need to minimize their power consumption in order to maximize battery runtime, except during short extremely busy periods. This requirement makes dc-dc converters usually operate in standby mode or under light-load conditions. Therefore, implementation of an efficient regulation scheme under a light load is a key aspect of dc-dc converter design. This paper presents a multiphase buck converter with a rotating phase-shedding scheme for efficient light-load control. The converter includes four phases operating in an interleaved manner in order to supply high current with low output ripple. The multiphase converter implements a rotating phase-shedding scheme to distribute the switching activity concentrated on a single phase, resulting in a distribution of the aging effects among the phases instead of a single phase. The proposed multiphase buck converter was fabricated using a 0.18 mu m bipolar CMOS DMOS process. The supply voltage ranges from 2.7 V to 5 V, and the maximum allowable output current is 4.5 A.