Method and apparatus for a control circuit with multiple operating modes

摘要

An example controller for use in a power converter includes an oscillator that is to be coupled to a switch of the power converter to determine a switching cycle period of the switch. The controller also includes means for controlling a duty cycle of the switch to regulate an output of the power converter and for maintaining a substantially constant rate of change of the duty cycle with respect to changes in a magnitude of a feedback signal as the controller transitions between duty cycle control modes such that a control loop gain of the power converter is substantially constant during the transition.

主权项

1. 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 switching cycle period of the switch; and means for controlling a duty cycle of the switch to regulate an output of the power converter and for maintaining a substantially constant rate of change of the duty cycle with respect to changes in a magnitude of a feedback signal as the controller transitions between a first duty cycle control mode and a second duty cycle control mode such that a control loop gain of the power converter is substantially constant during the transition, wherein the means for controlling the duty cycle of the switch varies a first parameter of the controller to vary the duty cycle with changes in the magnitude of the feedback signal to regulate the output of the power converter when the controller is in the first duty cycle control mode, and varies a second parameter of the controller to vary the duty cycle with changes in the magnitude of the feedback signal to regulate the output when the controller is in the second duty cycle control mode, wherein the first parameter is different from the second parameter, and wherein the controller transitions between the first duty cycle control mode and the second duty cycle control mode in response to the magnitude of the feedback signal reaching a first value.