Patent ID: 6078508
Filing Date: 2000-06-20
Classification: H02M

Abstract:
A self-oscillation type switching power supply apparatus comprising:a transformer having a primary winding, a secondary winding, and a feedback winding;a switching transistor for interrupting a current in said primary winding;a controlling transistor for controlling a positive feedback signal for said switching transistor from said feedback winding;a time constant circuit adapted to be charged at a predetermined time constant and to provide a controlling voltage to said controlling transistor;a light emitting element of a photocoupler provided in a circuit for detecting an output voltage or output current from the secondary of said transformer;a photodetector of said photocoupler connected between the feedback winding and said time constant circuit such that the time constant of said time constant circuit is changed in dependence on the detection of the output voltage or output current to stabilize the output voltage or output current; anda conducting path provided between an input power-supply voltage supplying section for the primary of said transformer and a voltage-supplying section for said photodetector of the photocoupler.