Control circuitry for controlling the duty cycle of a magnetizing switch of a power converter containing a demagnetizing switch is described. The magnetizing switch and the demagnetizing switch are switched on within a sequence of commutation cycles in a mutually exclusive manner. The control circuitry is configured, within a commutation cycle from the sequence of commutation cycles, to determine a sensed current signal indicative of a current through the magnetizing switch. The control circuitry determines a ramp signal by adding a slope compensation signal to the sensed current signal. The control circuitry determines a threshold signal and determines a duty cycle for the magnetizing switch for the commutation cycle by comparing the ramp signal with the threshold signal. The threshold signal and/or the slope compensation signal depend on the duty cycle for the magnetizing switch of a preceding commutation cycle from the sequence of commutation cycles.