SWITCH MODE POWER SUPPLY FOR REDUCING STANDBY POWER

摘要

PURPOSE: A switch mode power supply is provided to minimize the switching loss of a switching controller by controlling the operating frequency of the switching controller through an oscillator. CONSTITUTION: A feedback circuit part(10) charges and discharges a feedback voltage according to the amount of change of the output voltage of a load. A PWM(Pulse Width Modulation) control circuit part(20) generates a skip period in a PWM signal by comparing a feedback voltage with an internal comparison voltage. A stand-by mode determining part(30) outputs a signal by comparing a sensing voltage with an internal comparison voltage. A comparison voltage generating part(40) varies a comparison voltage according to the output signal of the stand-by mode determining part. A frequency generating part(60) controls the operation frequency by comparing a voltage which is charged in a triangle wave generating capacitor with a comparison voltage is outputted from the comparison voltage generating part.