Power supply circuit, switching regulator, and control circuit and control method thereof

摘要

The present invention discloses a switching regulator having a control circuit which includes an error amplifier circuit. The error amplifier circuit compares a feedback signal relating to an output voltage with a reference signal, to regulate the feedback signal to a level of the reference signal. When it is determined that the switching regulator has entered a shutdown procedure, the reference signal gradually decreases so that the output voltage is decreased to a shutdown threshold.

主权项

1. A switching regulator comprising:
a power stage circuit for converting an input voltage to an output voltage; an error amplifier circuit for comparing a feedback signal relating to the output voltage with a reference signal to generate an error amplified signal, wherein after it is determined that the switching regulator has entered a shutdown procedure, the reference signal gradually decreases along with a decrease of the input voltage; a pulse width modulation (PWM) signal generation circuit, for generating a PWM signal according to the error amplified signal to control the power stage circuit; and a reference signal generation circuit for generating a first reference signal according to the input voltage, wherein the first reference signal gradually decreases along with the decrease of the input voltage, and wherein when it is determined that the switching regulator has entered the shutdown procedure, the error amplifier circuit uses the first reference signal as the reference signal and compares the first reference signal with the feedback signal; wherein a relationship between the first reference signal and the input voltage is represented by the following equation:
Vref1=(Vin−Vofs)/K wherein Vref1 is the first reference signal, Vin is the input voltage, Vofs is a predetermined offset, and K is a constant or a function.