A Synchronous rectifier is an essential building block in the secondary side of the Flyback converter for designing efficient power supplies with high power density as motivated by emerging Energy standards. The ZXGD3101 controller when used with an appropriate MOSFET offers a higher efficiency than either a Schottky diode or an ultra-fast Silicon rectifier.
However, choosing the optimum Synchronous MOSFET can be difficult if reliant on an experimental trial-and-error method. Instead a straightforward design flow chart can be used to deal with the many device characteristics and controller trade-offs. This design note presents a design procedure that will help to select the best MOSFET for the ZXGD3101 Synchronous rectification controller. This design note should be used in conjunction with the spreadsheet of ZXGD3101 MOSFET selection tool.