Method and apparatus for controlling the maximum output power of a power converter

摘要

An example control circuit for use in a power converter includes an input voltage sensor, a current sensor, and a drive signal generator. The input voltage sensor generates a first signal representative of an input voltage (Vin) of the power converter. The current sensor generates a second signal representative of a switch current through a power switch of the power converter. The drive signal generator generates a drive signal to control switching of the power switch in response to the first and second signals. The drive signal generator sets a switching frequency of the drive signal based on a product K×Vin×t to control a maximum output power of the power converter, where K is a fixed number and t is a time it takes the second signal to change between two values of the switch current when the power switch is in an on state.

主权项

1. A control circuit for use in a power converter, the control circuit comprising:
an input voltage sensor coupled to generate a first signal representative of an input voltage (Vin) of the power converter; a current sensor coupled to generate a second signal representative of a switch current through a power switch of the power converter; and a drive signal generator configured to generate a drive signal to control switching of the power switch in response to the first and second signals, wherein the drive signal generator sets a switching frequency of the drive signal based on a product K×Vin×t to control a maximum output power of the power converter, wherein K is a fixed number and t is a time it takes the second signal to change between two values of the switch current when the power switch is in an on state.