Abstract: A secondary flyback core reset (SFCR) scheme for single-ended forward DC-to-DC converters is disclosed. The transformer secondary magnetizing inductor and a parasitic reset capacitance of the output forward rectifier diode form a secondary flyback reset circuit. The magnetic flux built up through the primary winding when the main switch is turned on is reset through this secondary flyback reset circuit when the main switch is turned off. The secondary flyback reset circuit initiates a half resonant cycle and resets the transformer. With proper design of the reset time, the maximum duty cycle of the main switch can go beyond 50%, while still using the first and third quadrants of the core B-H loop characteristics for optimum use of the core power density, and reduced RMS switching current and rectifier blocking voltages and power switch blocking voltage.