Power Integrations, Inc.
Introducing jitter to a switching frequency by way of modulating current limit

Abstract:

A controller includes a switch controller, a current limit generator, a jitter modulator, and an arithmetic operator circuit. The switch controller is coupled to generate a drive signal to control switching of a power switch in response to a current sense signal and a modulated current limit signal to control a transfer of energy from an input of a power converter to an output of the power converter. The current limit generator is coupled to generate a current limit signal. The jitter modulator is coupled to generate a jitter signal for jittering a switching period of the drive signal without an oscillator. The arithmetic operator circuit is coupled to receive the current limit signal and the jitter signal and is coupled to generate a modulated current limit signal in response to the current limit signal and the jitter signal.