An apparatus and method of switching a switch of a power supply are disclosed. According to aspects of the present invention, a method includes controlling a switch of a switching power supply to switch on and off within a switching cycle. The switching cycle has a substantially fixed period. One group of consecutive switching cycles is separated from a next group of consecutive switching cycles by a time of no switching. Each group of consecutive switching cycles has at least a predetermined minimum of two or more switching cycles. The time of no switching is adjusted in a closed loop to regulate an output of the switching power supply.