A High Power Density Quasi-Resonant Switched-Capacitor DC-DC Converter with Single Semi-Period Tank Current Modulation

Resonant switched-capacitors converters (ReSCC) are becoming an attractive alternative to traditional buck converters in volume-constrained and high conversion-ratio applications, thanks to their superior efficiency and power density. This work presents a new ReSCC topology derived from an interleaved ladder structure, which performs a nominal 4:1 down-conversion. A single semi-period modulated quasi-resonant control strategy is adopted to achieve continuous regulation of the output voltage below the nominal level. A novel modular small-signal model of the converter is presented to verify the single in-band singularity of the porposed topology. To validate the proposed ReSCC topology and control, a prototype converter for 12 V down-conversion towards the 2.5 to 3 V range has been developed. The prototype features high bandwidth closed loop control, light-load operating mode and switched soft-start. The use of PCB vias parasitic resonant inductors has allowed to obtain a state-of-the-art power density of 0.53 W/mm2 at 5 A current load. The peak efficiency is 94.4%, while the efficiency at power density reaches 85.9%.