METHOD AND APPARATUS FOR IMPLEMENTING AN UNREGULATED DORMANT MODE WITH AN EVENT COUNTER IN A POWER CONVERTER

A power converter includes an energy transfer element coupled between an input and an output of the power converter. A switch is coupled to the energy transfer element and a control circuit. The control circuit includes a drive signal generator to generate a drive signal to control switching of the switch to regulate the output of the power converter. An event detection circuit is coupled to the drive signal generator to indicate if a switching period of one switching cycle of the drive signal exceeds a threshold switching period. An event counter circuit is coupled to the event detection circuit to render dormant the drive signal generator for a period of time determined by a timer circuit if the event detection circuit indicates a period of a switching cycle of the drive signal exceeds the threshold switching period for a threshold consecutive number of switching cycles.