20 A Schottky for 60 V rails — conduction loss and thermal budget
The STMicroelectronics STPS20M60D is a 20 A, 60 V Schottky rectifier in a TO-220AC through-hole package.
580 mV Vf at 20 A — what it buys the power stage
At 20 A forward current the STPS20M60D drops 580 mV, which translates to 11.6 W of conduction loss at that current. That figure drives the heatsink selection — a TO-220 bolted to a modest finned extruded aluminium heatsink handles it in still air, but the junction temperature ceiling of 150 °C (max) sets the derating curve. The 125 µA reverse leakage at 60 V is a secondary thermal contributor; leakage doubles roughly every 10 °C above 25 °C junction, so the thermal design should keep Tj below 125 °C for margin.
Fast recovery — switching speed matters here
The STPS20M60D is rated as a fast recovery Schottky with recovery time under 500 ns at forward currents above 200 mA. That places it above standard 50/60 Hz rectifier diodes but below ultrafast epitaxial types. For a 100 kHz PFC boost or a 50–100 kHz forward converter secondary, the recovery charge is low enough that the MOSFET turn-on loss from diode reverse recovery stays manageable. At higher frequencies the switching loss in the diode itself starts to dominate the thermal budget.