Patent ID: 6038143
Filing Date: 2000-03-14
Classification: H02M

Abstract:
A self-oscillation switching power supply comprising: a transformer including a primary winding, a secondary winding and at least one control winding, a switching transistor for turning on and off the current flowing in said primary winding; a control transistor for controlling a feedback signal from said at least one control winding to said switching transistor; and a time constant circuit having a charging time which is charged by a voltage generated across said at least one control winding and which supplies a control voltage to said control transistor, and further comprising an electronic switch which is opened and closed in response to the feedback signal from said at least one control winding wherein an external voltage source is connected to said time constant circuit by said electronic switch so that the charging time of said time constant circuit is varied according to an output voltage detection signal dependent on an output voltage of the power supply.