JAJU858 December 2022
Calculate the secondary output diode or synchronous rectifier FET reverse voltage or blocking voltage needed (VDIODE_BLOCKING):
For this reference design, a 200-V, 24-A rated synchronous rectifier FET is selected for the +12-Vp rail to reduce losses. For the ±14 rails, Schottky diodes with 200-V voltage and 1-A forward current ratings are selected.
For the auxiliary rail, a Schottky diode with 400-V voltage and 1-A forward current ratings is selected. Here normally a 200-V diode is sufficient, but spikes over 153 V must be considered. If a 300-V diode, is selected, the diode does not bring any advantage because 300-V and 400-V small diodes have no difference in terms of reverse recovery time, nor VF.