An integrated circuit (IC) forming a pulse-width modulator controls the switching operation of an output stage of a switching power supply. A snubber capacitor that is coupled to a primary winding of a transformer of the output stage is used for producing a capacitive coupled charging current. The capacitive coupled charging current is coupled to a filter or charge storage second capacitor for producing in the second capacitor a first portion of a second power supply voltage. During a portion of a switching cycle of the output stage, the snubber capacitor is coupled to an inductor to form a resonant circuit. The resonant circuit produces in the second capacitor a second portion of the second power supply voltage for energizing the IC. The second power supply voltage is used for energizing the IC.