1200 V, 8 A, 100 ns — the high-voltage fast-recovery niche
The STTH812FP: This combination targets high-voltage power conversion stages — boost PFC, output rectification in flyback converters, and snubber clamping — where the blocking voltage exceeds 600 V and the switching frequency calls for recovery under 500 ns. The tab is electrically isolated from the die, so the diode can be bolted directly to a grounded heatsink or chassis without an insulating washer — a time-saver on assembly and a reliability win in vibration-prone environments.
Thermal and loss budget for the power stage
Junction temperature is rated to 175°C max, giving headroom in high-ambient PFC stages where the diode sees continuous conduction. The forward voltage is 2.2 V max at 8 A — the conduction loss at full load is 17.6 W, which must be sunk through the TO-220FPAC package's thermal resistance. At 1200 V reverse bias, leakage current is only 8 µA typical, so blocking losses are negligible in the thermal budget. The 100 ns trr places this diode in the fast-recovery class (under 500 ns per the JEDEC definition). At switching frequencies up to about 100 kHz, the recovery charge is low enough that the diode does not dominate the turn-on loss in the MOSFET — the main trade-off versus an ultrafast (35–60 ns) part is a slightly higher recovery peak current, which matters in CCM PFC designs.