30 ns recovery in an SMB package — what it does for the board
The STTH1R04UY is a 400 V, 1 A fast-recovery rectifier with a 30 ns reverse recovery time, qualified to AEC-Q101 for automotive use.
175 °C junction — under-hood headroom
Junction temperature rating goes to 175 °C. That extra thermal margin matters when the diode is near an engine block or inside a transmission controller.
SMB footprint — field-swappable with standard kit
SMB is a two-pad surface-mount package. It reflows with a standard hot-air station and the cathode band is clearly marked on the body.
Leakage and forward drop at the operating point
Reverse leakage is 5 µA at 400 V, and forward voltage is 1.6 V at 1 A. The leakage is low enough to not heat the junction in standby, and the Vf at full load is typical for a fast-recovery part in this voltage class — expect about 1.6 W conduction loss at 1 A, which the SMB package can sink with a reasonable copper pad.