This reference design is a low-cost: high-density USB adapter that uses the UCC28780 active-clamp flyback controller and UCC5304 isolated driver in a ZVS-flyback topology. The maximum power rating is 65 W at 20-V output but is adjustable for 20-V/15-V/9-V/5-V output voltage and 3 A. This design reaches a peak efficiency of 93.2%. The average efficiency and standby power levels are designed to meet DoE level VI and CoC Tier 2 limits. The compact design has dimensions of 45 mm by 55 mm by 25mm (62cc).