80 V, 20 A dual Schottky — what the ratings mean
The 800 mV forward voltage at 20 A is typical for a 80 V Schottky in this current class — the trade-off is a higher Vf than a lower-voltage Schottky, but you get the headroom for 48 V or 60 V rails with margin. The fast recovery spec (≤ 500 ns, > 200 mA) means it handles switching frequencies well above line frequency, making it usable in 100–200 kHz PFC or DC-DC stages where a standard recovery diode would burn.
STMicroelectronics lists the STPS40SM80CR as obsolete. No official successor is recorded in the lifecycle data, so a direct pin-compatible drop-in from ST is not guaranteed.
Housed in a TO-262-3 (I²PAK) through-hole package, the device is designed for bolting to a heatsink or PCB-mounted with the tab soldered to a copper plane. The junction temperature rating of 175 °C max allows high-temperature operation in cramped enclosures, but the 20 A per diode at 800 mV Vf means about 16 W dissipation per diode at full load — that demands a low thermal resistance path. The common-cathode configuration simplifies the layout for a center-tapped secondary or a two-diode boost stage.