SOFT START SCHEME FOR RESONANT CONVERTERS HAVING VARIABLE FREQUENCY CONTROL

摘要

A resonant mode power supply includes a soft-start circuit for, at start-up, sweeping the frequency of the power supply from a maximum value to a minimum value. The soft-start circuit performs this frequency sweep using the function F(x) = 1-e-t. Using this function, change in the frequency, and correspondingly the increase of the output voltage decreases over time, thereby allowing a feedback circuit of the resonant mode power supply to respond to the level of the output voltage and to begin regulation when the output voltage achieves the desired regulation level. As such, overshoot of the output voltage with respect to the regulation level is lessened, if not eliminated.