Patent ID: 8000114

Claim:
A controller for use in a power converter, the controller comprising: an oscillator to be coupled to a switch of the power converter to determine a time at which the switch is turned on at a beginning of a switching cycle of the switch; and a logic circuit to be coupled to the switch to determine a time at which the switch is turned off during the switching cycle of the switch, wherein the controller includes first and second duty cycle control modes responsive to a magnitude of a feedback signal to regulate power delivered to an output of the power converter, wherein in response to the magnitude of the feedback signal being below a threshold, the oscillator generates an output signal to fix a time period of the switching cycle of the switch during the first duty cycle control mode and wherein in response to the magnitude of the feedback signal being above the threshold, the oscillator generates the output signal to vary the time period of the switching cycle of the switch during the second duty cycle control mode.