Optimization and Design of a 48-to-12 V, 35 A Split-Phase Dickson Switched-Capacitor Converter

Abstract

The switched-capacitor converter (SCC) topology has been gaining attention in recent years because of their advantages of higher power density, switch utilization, and reduced component stress compared to existing converter topologies. However, SCCs have a major drawback in which capacitor charge redistribution results in significant current spikes. One method of addressing charge redistribution is split-phase operation, which accomplishes this by imposing voltage control on the SCC’s flying capacitors. However, an important design consideration was identified regarding the implementation of the split-phase Dickson SCC in high-current applications. Mismatched flying capacitors exhibit uneven charge rates, resulting in incomplete elimination of charge redistribution by split-phase control. This paper presents a discussion of the effects of mismatched flying capacitors on the operation of the split-phase Dickson SCC. Furthermore, design processes and test results of a prototype high-current split-phase Dickson SCC will be presented.