20 A, 600 V fast recovery diode — obsolete, sourced on the surplus market
The STTH2006W is a standard fast recovery diode from STMicroelectronics, rated for 20 A average rectified current and 600 V reverse voltage. The 1.75 V forward voltage at 20 A sets the conduction loss budget — at full rated current that is 35 W, so a substantial heatsink is non-negotiable.
70 ns trr — switching loss anchor for the PFC stage
The 70 ns reverse recovery time is the headline switching parameter. In a continuous-conduction-mode PFC boost running at 100 kHz, the recovery charge per cycle is small enough that the MOSFET turn-on loss stays manageable. Compare this to a standard recovery diode with trr in the microsecond range — the STTH2006W cuts the recovery spike and the associated EMI signature. The 25 µA reverse leakage at 600 V is a room-temperature figure; at 125°C junction expect it to climb, so the thermal design must account for leakage-induced self-heating at high line.
DO-247-2 through-hole — heatsink mounting matters
The DO-247-2 package with straight leads is a through-hole TO-247 variant. The large metal tab provides a low thermal resistance path to the heatsink — plan for a thermal pad or mica insulator with thermal grease.
STMicroelectronics lists the STTH2006W as obsolete. For new designs, consider the STTH2006CT (same current/voltage in a TO-220AB package) or a current-generation ST power diode in the same voltage class — but verify pinout and thermal pad compatibility.