Patent ID: 6285566
Filing Date: 2001-09-04
Classification: H02M

Abstract:
A self-oscillation switching power supply apparatus of the ringing choke converter type comprising:a transformer including a primary winding, a secondary winding, and a feedback winding;a switching transistor which oscillates with a self-oscillation period so as to have an on-time and an off time in response to a feedback signal from said feedback winding thereby turning on and off current flowing through said primary winding;a rectifying and smoothing circuit connected to said secondary winding;an oscillation frequency control circuit including a control transistor for controlling a control signal input to said switching transistor and a capacitor to be charged by a voltage induced across said feedback winding, the oscillation frequency control circuit controlling said control transistor in response to discharge of the capacitor so as to extend the off-time in the self-oscillation period of said switching transistor; andan oscillation frequency control disabling circuit for disabling the control of said control transistor in accordance with a remote signal.