What this Schottky pair is rated for
The STPS4045CWY is a dual Schottky rectifier in a common-cathode configuration, each diode rated for 20 A average rectified current and 45 V reverse voltage. The fast-recovery characteristic (≤500 ns, >200 mA) suits it for switching power supplies and freewheeling diodes in automotive DC-DC converters, where recovery time directly affects switching losses and EMI.
At 20 A forward current the maximum forward voltage is 760 mV. That is a typical Schottky figure for a 45 V device at this current density — low enough to keep conduction losses manageable in a 20 A rail, but not the ultra-low-Vf you would see in a 30 V part. The trade-off is reverse leakage: 200 µA at 45 V, which is acceptable for most automotive loads but worth checking if the diode sits across a high-impedance node in standby.
Housed in a TO-247-3 through-hole package, the same footprint used for many 20–30 A dual Schottky and ultrafast rectifiers. Through-hole mounting means the part is hand-solderable for prototypes and rework-friendly, but the thermal pad on the back of the TO-247 needs a good heatsink interface — the tab is electrically the cathode common, so no isolation washer is needed if the heatsink is grounded.