CURRENT MODE CONTROL ARRANGEMENT AND METHOD THEREOF

摘要

The present invention relates to control circuitry for providing a control signal in a PWM regulating power converter wherein an output parameter delivered by said converter is regulated to a desired value by PWM of current. The control circuitry includes: circuitry for receiving a sensed output parameter of said converter; circuitry for deriving therefrom an analogue average current demand signal (lavg_dem) corresponding to a current that would bring said converter into regulation; circuitry for receiving a sensed present value of said current within said converter to provide an analogue signal (I_fbk) representative thereof; circuitry for differencing said average current demand signal and said analogue signal to provide an error signal; a compensator (32) to which said error signal is applied, said compensator (32) being arranged to average said error signal over time to provide a second error signal; a sawtooth generator for providing an analogue signal as a PWM ramp; and a comparator (34) to which said ramp is applied to generate said control signal at the output thereof; wherein both said error signal and said a second error signal are simultaneously applied to said comparator (34) such that the error signals are additively compared to said ramp by said comparator (34); and whereby said control signal is responsive to both peak and average values of said current by means of said error signal and said second error signal respectively.