The STMicroelectronics STTH812D is a 1.2 kV, 8 A fast recovery diode in a TO-220AC package, built for power-switching roles where reverse recovery time matters — PFC boost stages, flyback snubbers, motor-drive freewheeling paths, and high-voltage DC-DC converters. Its 100 ns trr keeps switching losses low enough that you can push frequency without cooking the junction, and the 175 °C max junction temperature gives headroom for thermally constrained layouts.
100 ns trr — the switching edge
The 100 ns reverse recovery time is the spec that decides whether this diode works in a 100 kHz PFC or forces you to a slower, lossier SiC alternative. At 8 A and 1.2 kV, that recovery speed means the diode clears stored charge fast enough to avoid cross-conduction in a hard-switched bridge. Pair it with a gate driver that has enough peak current to snap the MOSFET on and off — the diode will keep up.
Active, ROHS3, through-hole — sourcing fit
No end-of-life notice, no last-time-buy pressure.