A reference design for a tiny, 65-W, 94% efficient ac/dc power adaptor for laptops measures just 3.19 in.3 and has a power density of 20 W/in3. This high efficiency means that the device runs cooler than standard ac/dc adapters.
At the core of this adapter is a synchronous rectifier circuit using 150-V, 7-mΩ EPC2033 eGaN FETs from Efficient Power Conversion Corporation (EPC). In this power conversion application, the eGaN FETs provide an 80% reduction in the driving power, a 25% reduction in on resistance, and 5% less power dissipation compared to devices based on silicon technology.
The reference design was developed by Rompower Energy Systems in Tucson, Ariz.