Adaptive duty cycle limiter

A duty cycle limiter limits a transfer of energy between an input source and a regulated output of an output regulator. The output regulator has a regulator characteristic and a computed duty cycle for controlling the transfer of energy between the input source and the regulated output. The duty cycle limiter comprises a digital controller that generates a reference level and that compares the regulator characteristic of the output regulator to the reference level to determine a maximum duty cycle. The digital controller controls the reference level at a frequency at least equal to a switching frequency of the output regulator. The digital controller limits the computed duty cycle to the maximum duty cycle.