METHOD AND APPARATUS FOR A CONTROL CIRCUIT WITH MULTIPLE OPERATING MODES

摘要

A method for controlling a power converter switch to regulate power delivered to an output of a power converter includes operating the power converter switch in first, second, and third duty cycle control modes in response to a feedback signal. The first duty cycle control mode includes modulating a peak switch current of the power converter switch in response to the feedback signal, and switching the power converter switch at a substantially fixed first switching frequency value. The second duty cycle control mode includes modulating the switching frequency in response to the feedback signal, and maintaining the peak switch current substantially at a peak switch current threshold value. The third duty cycle control mode includes modulating the peak switch current of the power converter switch in response to the feedback signal, and switching the power converter switch at a substantially fixed second switching frequency value.

主权项

1. A method for controlling a power converter switch to regulate power delivered to an output of a power converter, comprising:
operating the power converter switch in a first duty cycle control mode in response to a feedback signal being between a first feedback signal value and a second feedback signal value, wherein said first duty cycle control mode includes modulating a peak switch current of the power converter switch in response to the feedback signal, and switching the power converter switch at a substantially fixed first switching frequency value; operating the power converter switch in a second duty cycle control mode in response to the feedback signal being between the second feedback signal value and a third feedback signal value, wherein said second duty cycle control mode includes modulating the switching frequency in response to the feedback signal, and maintaining the peak switch current substantially at a peak switch current threshold value; and operating the power converter switch in a third duty cycle control mode in response to the feedback signal being between the third feedback signal value and a fourth feedback signal value, wherein said third duty cycle control mode includes modulating the peak switch current of the power converter switch in response to the feedback signal, and switching the power converter switch at a substantially fixed second switching frequency value.