Start Up Method for Switching Converters using the same Reference Voltage in the Error Amplifier and PWM Comparator

摘要

A switch-mode power supply is provided that includes a comparator for producing a pulse-width modulated (PWM) controller clock signal for controlling a power switch in the switch-mode power supply. The switch-mode power supply is configured to superimpose a DC-free version of a ramp voltage with an error voltage to produce a combined voltage. The comparator compares the combined voltage to a reference voltage to produce the PWM controller clock signal.

主权项

1. A circuit, comprising
an error amplifier configured to amplify a difference between a reference voltage and a scaled version of an output voltage for a switch-mode power supply to produce an error signal; a resistor having a first terminal configured to receive the error signal and having a second terminal; a ramp generator having a ramp output signal node coupled through a capacitor to the second terminal of the resistor; and a comparator configured to produce a pulse-width modulated (PWM) controller output clock responsive to a comparison of the reference voltage to a voltage for the second terminal of the resistor.