300 V, 15 A per leg, 20 ns trr — the fast-recovery diode pair
The STMicroelectronics STTH30W03CW is a 300 V, 15 A per-diode fast-recovery rectifier configured as a common-cathode pair in a single TO-247-3 through-hole package. Its 20 ns reverse recovery time (trr) puts it well inside the Fast Recovery =< 500ns class, making it a candidate for high-frequency rectification, PFC boost stages, and snubber clamp circuits where switching losses dominate.
The 20 ns trr is the headline number here. For a 15 A diode at 300 V, that recovery speed slashes the turn-off energy per cycle compared to a standard recovery part. In a continuous-conduction-mode PFC running 50–100 kHz, the difference in junction temperature is measurable. The 1.4 V forward drop at 15 A is a standard trade-off for a fast epitaxial diode in this voltage class — the thermal pad of the TO-247 needs to see a heatsink or forced air above about 8 A average per leg.
That means STMicroelectronics has ended production — no last-time-buy window remains open through the factory channel. No direct factory successor is listed on the official record, so a pin-compatible replacement search should target a 300 V, 15 A common-cathode fast-recovery diode in TO-247-3 from ST or an equivalent from a second manufacturer.
Layout and thermal note
Through-hole TO-247-3 with the tab at the common-cathode potential. The junction is rated to 175°C maximum, so the heatsink interface and mounting torque follow standard TO-247 practice. Reverse leakage sits at 10 µA at 300 V — negligible for most power circuits, but worth derating if the ambient runs above 100°C or the part operates near its voltage ceiling continuously.