Patent ID: 7638989
Filing Date: 2009-12-29
Classification: H02M

Abstract:
1. A pulse frequency modulating circuit for controlling a power converter comprising: an output voltage comparing circuit, for receiving a feedback voltage and comparing the feedback voltage with a reference voltage to output a comparing signal, the feedback voltage being in proportion to an output voltage of the power converter; a pulse generating circuit, for receiving the comparing signal and calculating a number of times of logic state changing of the comparing signal within a preset period to determine an enable time of a pulse signal, and outputting the pulse signal when the comparing signal being in a first logic state; and a switch circuit, coupled to the pulse generating circuit, the output voltage comparing circuit and the power converter, for transmitting the pulse signal from the pulse generating circuit to the power converter when the comparing signal being in the first logic state; wherein the power converter adjusts the output voltage based on the enable time of the received pulse signal.