Patent ID: 8537570
Filing Date: 2013-09-17
Classification: H02M,Y02B

Abstract:
1. A controller for use in a power supply, the controller comprising: a switch signal generator coupled to generate a switch signal to control switching of a switch of the power supply; a modulation circuit coupled to provide the switch signal generator with a modulation switching signal responsive to a switching frequency signal that represents an equivalent switching frequency of the switch at which an output of the power supply would be in regulation, wherein the modulation circuit modulates the period of the modulation switching signal to change the switching period of the switch signal in response to the switching frequency signal indicating that the equivalent switching frequency is greater than a reference frequency, and wherein the modulation circuit fixes the period of the modulation switching signal to fix the switching period of the switching signal in response to the switching frequency signal indicating that the equivalent switching frequency is less than the reference frequency; a multi-cycle modulator circuit coupled to the switch signal generator, wherein the multi-cycle modulator circuit enables the switch signal generator to provide the switch signal uninterrupted in response to the switching frequency signal indicating that the equivalent switching frequency is greater than the reference frequency, and wherein the multi-cycle modulator circuit disables the switch signal generator for a first time period and then enables the switch signal generator for a second time period in response to the switching frequency signal indicating that the equivalent switching frequency is less than the reference frequency, wherein the multi-cycle modulator varies the first time period to regulate the output of the power supply.