Wide Output Range High Efficiency MHz DC/DC for PD3.1 Charger

In this paper, an LLC DC transformer with cascaded buck based two-stage DC/DC converter is proposed and designed for PD3.1 charger application. A design guideline for cascaded buck considering specifications of PD3.1 is given. For DC transformer, a transformer design methodology considering real application issues is proposed, including the magnetic material maximum flux density. A prototype is built to verify the design, which achieves 97% efficiency under 48V output voltage and full load condition.