T01.7 - A 40W Dual-Inductor Hybrid Converter with Flying-Capacitor-Tapped Auxiliary Stage for Fast Transient Response in 48V PoL Automotive Applications

A flying-capacitor-tapped auxiliary converter is proposed for fast transient response in 48V Point-of-Load (PoL) converters. The auxiliary converter taps the flying capacitor of a 4-to-1 Dual Inductor Hybrid (DIH) converter to regulate the output voltage using a capacitor-current-based, Constant On-Time control scheme. The auxiliary inductor current, Iaux, is regulated by the DIH main stage such that Iaux = 0. A 40W experimental prototype was built which achieves a peak efficiency of 93.8%. Load transients of 12.5A were applied to the prototype with an output voltage deviation of 60mV being observed with an output capacitance of 650 μF.