A 48-to-6 V Multi-Resonant-Doubler Switched-Capacitor Converter for Data Center Applications

Abstract

Compared with conventional switched-capacitor (SC) converters with two operating phases, multi-phase SC converters can achieve the same conversion ratio with fewer capacitors and switches. This feature makes multi-phase SC converters an attractive candidate for applications with large conversion ratios. To further improve the performance by enabling soft-charging and soft-switching operations, SC converters can be transformed to resonant switched-capacitor (ReSC) converters with augmented inductor(s). This work presents an 8-to-1 multiphase ReSC converter design that features the least-possible number of switches and capacitors for the achieved gain. Both theoretical analysis and experimental results from a practical implementation are provided to demonstrate the benefits of the multi-phase resonant approach. A 48-to-6 V converter prototype with 40 A output current for data center applications was built and tested. The prototype achieved 98.6% peak efficiency (98.0% including gate drive loss) and 1675 W/in3 power density, achieving one of the best overall in-class performances.