A Novel Stacked High Step-down DC-DC Converter

A high efficiency and high power density 400/5V converter is proposed in this paper. Its working principle and designing method are illustrated in detail. The proposed converter contains two stacked LLC resonant converters. One LLC operates at unregulated mode which delivers most of the output power, while another LLC converter operates at regulated mode aiming to achieve constant output voltage. A 500kHz 25W stacked LLC resonant converter using GaN devices and planar matrix transformer are designed. Using the leakage inductance as the resonant inductor to further reduce the system volume and increase the power density The simulation and experimental results demonstrate the feasibility of the proposed converter.

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