A 10-MHz GaNFET-Based-Isolated High Step-Down DC–DC Converter: Design and Magnetics Investigation

This paper presents design of an isolated high-step-down dc-dc converter based on a class-DE power stage, operating at a 10-MHz switching frequency using enhancement-mode gallium nitride transistors. The converter operating principles are discussed, and the power stage design rated for 20 W is presented for a step down from 200-300 V input to 0-28 V output. Commercially available magnetic materials were explored and the high-frequency resonant inductor and transformer designs using a low-loss Fair-Rite type 67 material are presented. Finite-element simulations have been performed to estimate the parameters of magnetics at 10-MHz. Experimental results are presented at 12 W, 254 V input to 22 V output and 5 W, 254 V input to 14 V output on a laboratory prototype operating at 10-MHz. At 20 W, the experimental prototype achieved an efficiency of 85.2%.