A High Performance 48-to-8 V Multi-Resonant Switched-Capacitor Converter for Data Center Applications

Abstract

Resonant switched-capacitor (SC) converters are becoming increasingly attractive for high performance applications due to their efficient utilization of switches and use of high energy density capacitors. Multiphase SC converters can offer further improvements in performance, as they can achieve the same conversion ratio as traditional two-phase SC converters with fewer capacitors and switches, making them ideal for large conversion ratio applications. This paper presents theoretical analysis and experimental results for a resonant multi-phase SC converter comprising a cascaded series-parallel topology derived from the conventiona1 4-to-1 series-parallel converter. The proposed converter can achieve a 6-to-1 conversion ratio with the same number of switches and capacitors as the 4-to-1 series-parallel converter. A 48-to-8 V prototype designed for data center applications was built and tested with 40 A maximum output current. The prototype achieved 99.0% peak efficiency (98.5% including gate drive loss) and 2230 W/in3 power density, demonstrating one of the best in-class performances.