What this dual Schottky does
The STPS2545CTY is a 45 V, 12.5 A per diode Schottky rectifier in a TO-220-3 package with a common-cathode configuration. The 570 mV forward voltage at 12.5 A (per diode) keeps conduction losses manageable in OR-ing, reverse-polarity protection, and output rectification stages.
The 45 V reverse voltage (Vr) is the maximum DC blocking voltage; for a 12 V automotive rail this provides adequate margin, but for 24 V systems or higher transients you need a higher Vr part. The 570 mV forward voltage at 12.5 A is a typical figure; at lower currents the Vf drops, improving light-load efficiency. The 125 µA reverse leakage at 45 V is specified at 25°C; leakage doubles roughly every 10°C rise, so at 125°C junction expect several milliamps — factor this into standby power budgets.
Through-hole TO-220-3 with a metal tab. The tab is electrically common with the cathode (center pin). For full current rating, the tab must be heatsunk.