30 ns recovery — the spec that keeps the snubber cool
The STTH4R02S is a 200 V, 4 A fast recovery diode from STMicroelectronics, built for circuits where a standard recovery part would ring the node and burn passives. The 30 ns reverse recovery time is the key differentiator — it keeps the stored charge low enough that a PFC boost or flyback clamp can run without a heavy snubber.
175 °C junction — thermal headroom in a SMC body
The maximum junction temperature is rated at 175 °C, which gives real margin in a SMC package when the diode is mounted on a standard FR-4 pad. Reverse leakage at 200 V is 3 µA — negligible at room temperature, but it climbs with junction heat; the 175 °C ceiling means the leakage current stays within the thermal budget even under sustained full-load conditions.