30 A, 100 V — the conduction loss and thermal budget
The STPS30SM100SG-TR is a 100 V, 30 A Schottky rectifier in the D²PAK surface-mount package. The 30 A average rectified current (Io) is the continuous forward rating at the case temperature that keeps the junction below the 150°C max — not a surge figure, but the steady-state load the diode must carry in the power supply or OR-ing circuit. Forward voltage drop is 870 mV max at 30 A — this sets the conduction loss floor. At 30 A, the Vf×If product is 26.1 W, which must be dissipated through the D²PAK's exposed pad to the PCB copper plane. The thermal resistance from junction to case (RθJC) determines the copper area needed to stay under 150°C junction temperature at the ambient air temperature of the enclosure. Reverse leakage is 45 µA at 100 V — this is the blocking-state loss. Leakage doubles with every 10°C rise in junction temperature, so at 125°C junction the leakage current is roughly 360 µA, adding about 36 mW of standing loss. In a lightly loaded OR-ing diode application at elevated ambient, leakage can dominate the thermal budget at the high end of the temperature range.
Schottky fast-recovery switching
The Schottky barrier technology gives this diode a fast recovery time — under 500 ns at forward currents above 200 mA. This means negligible reverse-recovery charge (Qrr) compared to a PN-junction rectifier, so the switching losses in a 50-100 kHz PFC boost or output rectifier stage are dominated by the output capacitance (Coss) discharge, not the recovery spike. The fast recovery characteristic also reduces EMI — the lack of a reverse-recovery current tail means the diode turns off cleanly without the high-frequency ringing that a standard recovery diode would inject into the switching node. This is a practical advantage in a flyback or forward converter where the secondary-side rectifier noise couples through the transformer.
D²PAK — surface-mount power package
The TO-263-3 (D²Pak) package is the surface-mount version of the through-hole TO-220. The exposed tab on the bottom is the cathode connection and the primary thermal path — it must be soldered to a copper pad on the PCB with sufficient area to sink the heat. A typical 2 oz copper pour of 6 cm² per watt of dissipation keeps the junction temperature within the 150°C max at 25°C ambient. The tape-and-reel packaging indicates this is the reeled variant for automated pick-and-place assembly. The base product number STPS30 covers the 30 A Schottky family; the SM100SG suffix specifies the 100 V version in the D²PAK with the standard guard ring.