SWITCHING CONTROL CIRCUIT AND SWITCHING POWER SUPPLY

摘要

A switching element controls supply of a primary current to a transformer in a switching power supply. An amplifier circuit amplifies an output ripple of an auxiliary winding of a transformer. A fluctuation generator circuit generates a fluctuating signal, based on an output of the amplifier circuit. A basic signal generator circuit generates a PWM basic signal whose frequency fluctuates according to the fluctuating signal. A control circuit ON controls the switching element when receiving the PWM basic signal, and OFF controls the switching element when receiving an OFF signal based on output feedback of the switching power supply.