Patent ID: 8669751

Claim:
A power supply, comprising: an energy transfer element coupled to transfer energy between an input and an output of the power supply; a power switch coupled to the energy transfer element; and a controller coupled to provide a drive signal to control switching of the power switch, wherein the controller includes: a logic block coupled to generate the drive signal to regulate an output of the power supply in response to a clock signal having a frequency that decreases responsive to a time period of the drive signal, wherein a decrease in the time period of the drive signal is representative of an increase in an input voltage of the power supply; and an oscillator coupled to generate the clock signal in response to a waveform having an amplitude swing, wherein the oscillator alters the amplitude swing of the waveform responsive to the time period of the drive signal; wherein the amplitude swing is a difference between an upper reference and a lower reference of the oscillator, and wherein the oscillator alters the waveform by adjusting at least one of the references responsive to the time period of the drive signal.