Secondary-side adaptive digital controlled series resonant DC-DC converters for low voltage high current applications

It is more difficult for VRMs to supply power to future microprocessors, which need lower supply voltage, large current and large current slew rate. Most of today´s VRMs are with inductor-capacitor type output filters. The inductor in the output filter limits the current transient speed. Hence, the secondary-side controlled series resonant converter with capacitor type filter is introduced in this paper to overcome this limitation. The lack of the inductor in its output filter makes it have very quick dynamic response. Also an adaptive control scheme is proposed to control the current-type synchronous MOSFETs, which eliminates the current sensor in the power path. Theoretical analysis and simulation results verify the proposed concept.