SOFT START METHOD, DEVICE AND SYSTEM FOR POWER SUPPLY

摘要

A soft start method, device and system for a power supply. A small duty cycle signal generation unit (320, 122) receives a clock signal (CLK) and generates a signal with a small duty cycle according to the clock signal (CLK). The signal with a small duty cycle is output to a switch (330, 123) and controls the switch (330, 123) to switch on and off periodically. When the switch (330, 123) turns on, a charging current charges a capacitor (340, 124) through the switch (330, 123). When the switch (330, 123) turns off, the charging current is cut off. An analog multiplexer (350, 125) compares the voltage of the capacitor (340, 124) with a reference voltage (VREF), and outputs the smaller one to one input of an error amplifier (360, 126). Another input of the error amplifier (360, 126) is connected to a feedback voltage (VFB).