Bel Fuse, Inc.

Yi Jiang

Guichao Hua

Ya Liu

Daifu Xiong

A converter includes a transformer having a primary winding, a secondary winding and an auxiliary winding, a first switching device for connecting an input voltage to the primary winding of the transformer, an output circuit connected to the secondary winding, a controller, and an integrated active clamp and primary bias circuit. The integrated active clamp and primary bias circuit includes the auxiliary winding and a second switch providing a bias voltage to the controller to alternately operate the first and second switches between conductive and non-conductive states. When the first switch is conductive the second switch is nonconducting and power is transferred from the primary winding to the output circuit via the secondary winding and from the auxiliary winding to the controller. When the first switch is nonconducting, the second switch is conducting and the voltage across the primary winding is clamped.

Converter with integrated active clamp circuit and bias circuit

A self-driven synchronous rectification circuit which includes two power switches S and S ; a transformer Tr having a primary winding N , a secondary winding N and an auxiliary winding N ; two secondary synchronous rectifiers S and S ; two diodes D and D ; two switching transistors Q and Q ; and two zener diodes ZD and ZD . The number of auxiliary winding turns N of the transformer Tr ensure that the synchronous rectifiers S and S are supplied with an adequate gate-drive voltage. When S conducts, the gate-drive voltage of S is clamped by D and Q . Likewise, when S conducts, the gate-drive voltage of S is clamped by D and Q . ZD and ZD operate to restrain the gate over voltage of S and S , respectively. When the gate drive voltage of S is clamped by D and Q , Q disables D and when the gate drive voltage of S is clamped by D and Q , Q disables D .

Growing community of inventors

Hangzhou, China

Yi Jiang