Cascaded Switched-Capacitor dc-dc Converters for a USB Power Delivery Compliant Charger

Abstract

The improvements in modern circuit technology reduce system size, improve the efficiency and reduce the cost. Utilization of soft-switching resonant power converters give high density high effeciency power converters for narrow output voltage ranges. To overcome this a cascaded switched-capacitor dc-dc converter is used to implement a Universal Serial Bus Power Delivery compliant charger. The converter uses a custom designed application specific integrated circuit designed for switched-capacitor dc-dc converters and wide bandgap technology allowing high frequency, high power design. The converter achieves peak efficiencies up to 98% at 60W output power with a corresponding junction temperature of 50◦C. Worst case junction temperatures reach 64◦C and is viable for use in long-term battery charger systems. The cascaded power stages take up 14mm×22mm.