1200 V, 8 A, 100 ns trr — the fast recovery diode for high-voltage switching
The STMicroelectronics STTH812G is a 1200 V, 8 A fast recovery rectifier with a 100 ns reverse recovery time, housed in a D2PAK (TO-263AB) surface-mount package. It is designed for high-frequency power conversion where fast switching and low recovery losses matter — think power-factor-correction stages, output rectification in switch-mode supplies, solar inverter boost stages, and snubber circuits across 400 V bus architectures.
A 100 ns reverse recovery time at 1200 V blocking is the spec that separates this diode from standard-recovery parts. In a hard-switched PFC or flyback converter, that trr directly reduces turn-on losses in the MOSFET and lowers EMI at the switching edge. The 2.2 V forward drop at 8 A is the conduction-loss number to plug into the thermal model — expect to budget copper area or a heatsink if the average current is above 4 A continuous. The 8 µA leakage at 1200 V is tight enough for high-impedance bus holding, but confirm derating above 125°C junction.
Every unit sourced through that channel should be physically authenticated — the D2PAK laser etch, date-code consistency, and package marking must match ST's factory format for the week code. A decap and X-ray inspection is the only way to confirm the die matches the original ST design, especially given the 1200 V rating where a counterfeit die could fail catastrophically under surge.