This reference design uses the UCC28700 in a quasi-resonant flyback to generate an isolated 5V at up to 2.1A. The UCC28700 implements primary-side regulation, eliminating the need for an opto-coupler and reducing the total component count. This results in a compact and cost effective design. The populated circuit boards in this design occupy the space of a 1" by 1" by 1" cube. The TPS2511 USB power switch also offers the data line control to charge most smart phones and tablets. The energy saving features of the UCC28700 allow this design to consume less than 30mW when plugged into the wall with no device attached to the USB port.