This reference design uses the UCC28780 active clamp flyback controller to generate a 20-V/15-V/9-V/5-V adjustable output voltage. The maximum power rating is 65 W at 20-V output and up to 3 A at all other output voltage settings. This design reaches a peak efficiency of over 93% using silicon FETs: due to zero voltage switching (ZVS) and recaputuring the leakage energy. The high efficiency enables a small form factor and a high power density.