The forward drop is specified at 570 mV maximum at 10 A, which keeps conduction losses manageable in a 20 A total-output OR-ing or center-tapped secondary rectifier. The junction temperature rating of 175°C maximum gives headroom for high-ambient or forced-cooling designs, but the D2PAK (TO-263-3) surface-mount package relies on the PCB copper for heat spreading — the tab is the cathode common terminal, so the thermal pad layout is critical.
STMicroelectronics lists the STPS2045CG as obsolete. For BOM lines that already use this part, procurement will need to source from independent distributors or broker channels.
Replacement fit — same package, same function
The STPS2045CT is a through-hole TO-220 version of the same die — same 45 V, 10 A per diode, common-cathode pair. If your board is laid out for the D2PAK footprint, the STPS2045CT will not drop in without a mechanical adapter or a board spin. For a pin-compatible surface-mount replacement, look for other common-cathode Schottky dual diodes in D2PAK (TO-263-3) with a 45 V or higher rating and at least 10 A per leg; the 570 mV forward drop at 10 A is a typical benchmark for a 45 V Schottky in this package class.