公开(公告)号：US20180212528A1

公开(公告)日：2018-07-26

申请号：US15865212

申请日：2018-01-08

Applicant: RICHTEK TECHNOLOGY CORPORATION

Inventor： Chien-Fu Tang ,  Su-Yuan Lin ,  Yi-Wei Lee ,  Isaac Y. Chen

IPC: H02M3/335 ,  H02M1/36 ,  H02M1/08

CPC classification number: H02M3/33592 ,  H02M1/08 ,  H02M1/32 ,  H02M1/36 ,  Y02B70/1475

Abstract: A flyback power converter circuit converting an input voltage to an output voltage includes a transformer, a power switch, a synchronous rectifier (SR) switch, and a secondary side control circuit. The secondary side control circuit controls the SR switch to be ON when the power switch is OFF. The secondary side control circuit includes a driving switch for controlling the SR switch, a synchronous control circuit powered by a voltage related to the output voltage, which controls the driving switch to operate the SR switch, and a clamping circuit including a clamping switch and a clamping switch control circuit. The clamping switch control circuit controls the clamping switch according to a current inflow terminal voltage of the clamping switch and/or the voltage related to the output voltage, such that, during a secondary side power-on period, an equivalent impedance of the current inflow terminal of the clamping switch is smaller than a predetermined clamping impedance.

公开(公告)号：US10355612B2

公开(公告)日：2019-07-16

申请号：US15865212

申请日：2018-01-08

Applicant: RICHTEK TECHNOLOGY CORPORATION

Inventor： Chien-Fu Tang ,  Su-Yuan Lin ,  Yi-Wei Lee ,  Isaac Y. Chen

IPC: H02M3/335 ,  H02M1/36 ,  H02M1/32 ,  H02M1/08

Abstract: A flyback power converter circuit converting an input voltage to an output voltage includes a transformer, a power switch, a synchronous rectifier (SR) switch, and a secondary side control circuit. The secondary side control circuit controls the SR switch to be ON when the power switch is OFF. The secondary side control circuit includes a driving switch for controlling the SR switch, a synchronous control circuit powered by a voltage related to the output voltage, which controls the driving switch to operate the SR switch, and a clamping circuit including a clamping switch and a clamping switch control circuit. The clamping switch control circuit controls the clamping switch according to a current inflow terminal voltage of the clamping switch and/or the voltage related to the output voltage, such that, during a secondary side power-on period, an equivalent impedance of the current inflow terminal of the clamping switch is smaller than a predetermined clamping impedance.