What the 100 V / 30 A rating means on a power rail
The STPS30100ST is a 100 V, 30 A Schottky rectifier in a TO-220 through-hole package. The 100 V reverse voltage covers 48 V bus rails with margin for transients, while the 30 A average forward current suits output rectification in medium-power supplies and polarity protection on high-current loads. Forward voltage drop is 800 mV max at 30 A — the conduction loss at full load is 24 W, which the TO-220 copper tab must sink to keep the junction below the 150 °C absolute maximum. That thermal budget drives the heatsink choice, not the bare current rating. Reverse leakage is 175 µA at 100 V and 25 °C; it rises exponentially with junction temperature, so at 125 °C the leakage can dominate the off-state power loss in a lightly loaded rail.
Package and mounting for the BOM
TO-220-3 through-hole package (supplier device package TO-220) — the tab is the cathode, and the leadframe is designed for wave or hand-solder. The tube packaging means the parts arrive aligned for auto-insertion, but the tube count is lot-specific.