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 60 W output power with a corresponding junction temperature of 50 • C. Worst case junction temperatures reach 64 • C and is viable for use in longterm battery charger systems. The cascaded power stages take up 14 mm × 22 mm.

Implementation of Time Division Multiplexing With Commercial Flyback Controller for Multi-Outputs USB Power Delivery Charger

“…This wide output voltage range, together with the universal input range (90 -264 Vac wide) requirement, poses design challenges on the USB-PD chargers. This has been addressed by adopting typologies such as quasiresonant or active clamp flyback [2] [3], current-source resonant converter [4], cascaded switched-capacitor converter [5], and two-stage architecture [6], as well as advanced controls [7] and [8]. Power density can also be improved by shrinking the double-line-frequency dependent bulk capacitor by using a half-bridge series-stacked buffer [6] or a self-driven thyristor [9].…”