The breakdown voltage rating of the diode (D1) is preferred to be 25% higher than the maximum input voltage. The current rating for the diode must be equal to the maximum output current for best reliability in most applications. In cases where the duty cycle is greater than 50%, the average diode current is lower. In this case it is possible to use a diode with a lower average current rating, approximately (1 – D)IOUT; however, the peak current rating should be higher than the maximum load current. A 0.5-A to 1-A rated diode is a good starting point.