IS22.3 - High Efficiency and High-Power Density 35W USB-PD Adapter Using Asymmetrical Half-Bridge Flyback and GaN Device

This talk presents asymmetrical half-bridge (AHB) Flyback converter and GaN device for high power density and high efficiency charger and adapter applications. AHB Flyback has some unique characteristics that can be utilized for high power density adapter and charger applications. The use of 600V GaN device as a primary switch is a great compliment for this topology in achieving high full load and meeting average efficiency specs across 5-20V USB-PD output voltage range. However this topology is relatively new and can be challenging to design and optimize. This presentation will provide key design consideration and optimization technique in designing AHB-Flyback for USB-PD adapter. The results will be demonstrated using a 35W USB-PD adapter demonstrator board which uses RM7 transformer and GaN device to help achieve ~25W/cu inch power density. Finally, average efficiency exceeding power supply specs (DOE and COC) and 30mW standby power will also be demonstrated.