The STPSC12H065D is a Silicon Carbide Schottky diode rated for 650 V reverse voltage and 12 A average rectified current. That combination — SiC Schottky at 650 V — puts it squarely in power-factor-correction stages, high-frequency SMPS outputs, and on-board charger circuits where reverse-recovery losses in a standard ultrafast diode would eat into efficiency. The 1.75 V forward drop at 12 A is the conduction-loss figure you budget for in the thermal model. At 12 A continuous, that's 21 W of forward loss before switching losses — the TO-220AC package needs a heatsink sized for that dissipation.
175°C junction — thermal headroom for compact builds
Rated junction temperature spans -40°C to 175°C. The 175°C upper limit is wider than a typical 150°C Si diode, which gives you extra margin in a tightly-packed PFC stage or a hot engine-bay environment. The reverse leakage at 650 V is 120 µA — that figure climbs with temperature, so at 150°C junction the leakage contribution to the thermal budget needs checking.