Surge protection circuit for a switching mode power supply

摘要

A surge protection circuit for a switching mode power supply utilizing the switching phase difference of substantially 180 degree between primary and secondary coils of a switching power supply transformer snubs surges induced on both sides of the power supply transformer by attenuating the surges induced during ON/OFF operations of a switching transistor which controls the power supply transformer. Accordingly, heat caused during the ON/OFF operation of the switching transistor is reduced and secondary rectifier diodes connected to the secondary winding of the power transformer are protected from damages The surge protection circuit uses a pair of capacitors connected in series between a control terminal of the primary coil and an output terminal of the secondary coil of the switching power supply transformer for snubbing bi-directional surges induced by the ON/OFF operation of the switching transistor.