A switching power converter provides regulated voltage to a load. The switching power converter comprises a transformer including a primary winding coupled to an input voltage and a secondary winding coupled to an output of the switching power converter. The switching power converter further comprises a power switch coupled to the primary winding and a rectifier coupled to the secondary winding. Current is generated in the primary winding responsive to the power switch being turned on and not generated responsive to the power switch being turned off. A detection circuit measures a voltage across the rectifier. If the detection circuit detects a decrease in the voltage across the rectifier outside of a blanking period, the detection circuit generates a current pulse in the secondary winding of the transformer.