Abstract: A synchronous rectifier control circuit improves energy conversion efficiency and uses a signal produced by a secondary winding of a transformer in a rectifier circuit to control a low-impedance and a low power consuming current switch such as a JFET and a MOSFET in a synchronous rectifier circuit to substitute a high power consuming diode rectification and appropriately rectify and extend the ON time of the current switch to prevent the positive and negative phases of the current switch to be turned on simultaneously, which will cause a large current to burn the current switch. The invention includes a protection circuit having an under voltage lock out circuit for an interrupt output function, so that if an insufficient instant power voltage occurs, the power is turned on or off to interrupt all outputs and force the current switch of the rectifier circuit to turn off, and prevent the output of an unstable working voltage of the rectifier control circuit or the abnormal operation of the current switch.

Abstract: A synchronous rectifier control circuit improves energy conversion efficiency and uses a signal produced by a secondary winding of a transformer in a rectifier circuit to control a low-impedance and a low power consuming current switch such as a JFET and a MOSFET in a synchronous rectifier circuit to substitute a high power consuming diode rectification and appropriately rectify and extend the ON time of the current switch to prevent the positive and negative phases of the current switch to be turned on simultaneously, which will cause a large current to burn the current switch. The invention includes a protection circuit having an under voltage lock out circuit for an interrupt output function, so that if an insufficient instant power voltage occurs, the power is turned on or off to interrupt all outputs and force the current switch of the rectifier circuit to turn off, and prevent the output of an unstable working voltage of the rectifier control circuit or the abnormal operation of the current switch.

Abstract: A synchronous rectifying control circuit for utilizing in a forward topology of rectifying circuit. The circuit controls a first current switch and a second current switch provided on both ends of a secondary of a transformer. Two sets of the same of control circuits are utilized to control and adjust respectively the post and future periods of the conductive time and the driving synchronous rectifying switches are extended to replace the conventional of rectifier diodes rectifying method. An improved synchronous rectifying control circuit comprises pulse interruptive protection circuit to prevent the cross-conduction between two current switches and an anti reversing protection circuit to prevent a reverse current from flowing back to the ground.