Method and apparatus to reduce audio frequencies in a switching power supply

A controller for use in a power supply regulator, the controller comprising:

• a switch signal generator coupled to generate a switch signal to control switching of a switch of the power supply regulator;
• a modulation circuit coupled to provide the switch signal generator with a pulse width modulated switching signal responsive to a feedback signal that indicates a load condition at an output of the power supply regulator, wherein the modulation circuit modulates the duty cycle of the pulse width modulated switching signal to provide a fixed peak switching current in the switch in response to the feedback signal indicating that the load condition is a light load condition, and wherein the modulation circuit modulates the duty cycle of the modulated switching signal to provide a variable peak switching current in the switch that is proportional to the feedback signal in response to the feedback signal indicating that the load condition is other than the light load condition;
• and
• 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 feedback signal indicating that the load condition is other than the light load condition, 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 feedback signal indicating that the load condition is the light load condition, wherein the first time period is adjusted in response to the feedback signal to regulate the output.