PWM GENERATION FOR DC/DC CONVERTERS WITH FREQUENCY SWITCHING

摘要

A method for generating a pulse width modulation (PWM) control signal includes generating a sawtooth ramp signal at a first frequency under standard operating conditions using a ramp generator, generating a PWM square wave having a rising edge at a falling edge of the sawtooth ramp signal and a falling edge when the sawtooth ramp signal exceeds an error threshold, adjusting the frequency of the sawtooth ramp in response to a changed operating parameter of the ramp generator, and adjusting a peak input voltage of the ramp generator simultaneous with adjusting the frequency of the sawtooth ramp, thereby preventing one of a voltage overshoot and a voltage undershoot.

主权项

1. A method for generating a pulse width modulation (PWM) control signal comprising the steps of:
generating a sawtooth ramp signal at a first frequency under standard operating conditions using a ramp generator; generating a PWM square wave having a rising edge at a falling edge of the sawtooth ramp signal and a falling edge when said sawtooth ramp signal exceeds an error threshold; adjusting the frequency of the sawtooth ramp in response to a changed operating parameter of the ramp generator; and adjusting a peak sawtooth voltage of the ramp generator simultaneous with adjusting the frequency of the sawtooth ramp, thereby preventing one of a voltage overshoot and a voltage undershoot.