A Fixed Frequency Dual-Mode DC-DC Buck Converter with Fast-Transient Response and High Efficiency Over a Wide Load Range

Abstract

Maintaining high efficiency and achieving fast dynamic response over wide load condition are extremely important in most modern power management applications, and also for various typical load demands. In this paper, we present the design of a fixed frequency hysteretic current (FFHC) controlled dual-mode tri-state dc-dc step-down (Buck) switching regulators/converters for wide load variation. Depending on the load requirements, it can adaptively switch between two operating modes —pseudo-continuous continuous mode (PCCM) to discontinuous conduction mode (DCM) and adjust the switching frequency of operation accordingly. Moreover, based on simplified discretized model or map, we also show that under certain conditions the proposed dual-mode tri-converter is not only useful for achieving the fast dynamic responses under wide load range, but also improve the power conversion efficiency, especially, at light load condition.