Enabling circuit for switching power supply chip, switching power supply chip and control method

Abstract

The application relates to an enabling circuit for a switching power supply chip, a switching power supply chip and a control method. The enabling circuit includes an input module and a delay output module; the input terminal of the input module is used to input the first level control signal, and the output terminal It is used to generate a first output control signal according to the first level control signal, and turn off the power tube through the first output control signal; the input terminal of the delay output module is used to input the first output control signal, and an output terminal is used for delay preset After a time, a second output control signal is generated according to the first output control signal, and the residual charge of the compensation capacitor in the error amplifier circuit is discharged through the second output control signal; the other output terminal is used to delay the preset time, according to The first output control signal generates a third output control signal, and the power supply circuit is turned off through the third output control signal. By discharging the residual charge of the compensation capacitor, the phenomenon of unstable output voltage when the enabling circuit is restarted is avoided.

Description

technical field [0001] The present application relates to the field of switching power supply circuits, in particular to an enabling circuit for a switching power supply chip, a switching power supply chip and a control method. Background technique [0002] When the switching power supply chip is working normally, it can control the power on and off of the switching power supply chip by controlling the EN pin (enable pin). Using the EN pin to shut down can reduce the shutdown power consumption of the switching power supply chip. Because it is simple and convenient to control the switch of the switching power supply chip through the EN pin, some users will use high-frequency signals to control the EN pin to achieve the rapid switching of the switching power supply chip on and off, and to achieve the purpose of adjusting the output voltage. However, when switching power supply chips in some application fields control the EN pin to shut down at high frequency, the internal logi...

AI Technical Summary

Problems solved by technology

However, when switching power supply chips in some application fields control the EN pin to shut down at high frequency, the internal logic circuit of the chip will work abnormally and the output voltage will be unstable.

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