PULSE WIDTH MODULATED CONTROLLER APPLIED TO SWITCH-TYPE VOLTAGE REGULATOR

摘要

A PWM controller applied to switch-type voltage regulator includes an error amplifier, a soft-start control circuit, a compensating load and a comparator. The error amplifier receives a reference voltage signal and a feedback voltage signal and outputs an error current signal according to the received feedback voltage signal and the reference voltage signal. The soft-start control circuit outputs a compensating current signal according to at least one soft-start control signal. The compensating load receives the error current signal and the compensating current signal, and outputs a compensating signal. The comparator receives a ramp signal and the compensating signal, and outputs a pulse width modulated (PWM) signal. When a supply voltage rises, the error amplifier is compensated with a preset soft-start compensating current to a circuit common ground VSS, so that the error signal slowly rises during the soft-start control process. Therefore, the function of soft-starting is effectuated.