50 ns reverse recovery at 8 A — the switching loss floor
The STTH8R04D is a 400 V, 8 A fast recovery diode in a TO-220AC package, built for continuous conduction in the 8 A average rectified range. The 50 ns reverse recovery time (trr) sets the switching loss ceiling — at a 100 kHz hard-switched PFC stage, the recovery charge per cycle is low enough that the junction stays within the -40°C to 175°C operating range without oversized heatsinking. Forward voltage is 1.5 V max at 8 A — the conduction loss at full load is 12 W, which drives the thermal design. The 10 µA reverse leakage at 400 V is a room-temperature spec; expect it to rise with junction temperature, so the heatsink must keep the die below the 175°C absolute maximum under steady-state fault conditions.
TO-220AC through-hole — board-fit note
The TO-220AC package is a through-hole, 2-lead form factor with a metal tab for heatsink mounting. The base part number STTH8 covers the family; the full suffix R04D identifies the 400 V, 50 ns variant. Tube packaging is standard for this part — no reel or tape option is listed.