800 V off-state — line-voltage margin for 240 VAC circuits
The TYN804RG is a standard-recovery SCR from STMicroelectronics, rated for 800 V off-state blocking voltage and 4 A RMS on-state current. Gate trigger current is 15 mA max, which means a standard MOC30xx or similar optocoupler can fire it directly — no intermediate driver stage needed.
4 A RMS continuous — thermal budget in a TO-220
The 4 A RMS (2.5 A average) on-state rating is the continuous load ceiling. In a TO-220 package, the junction-to-case thermal resistance sets the practical limit: at 4 A RMS with a 1.8 V Vtm drop, conduction losses run about 7.2 W. That needs a heatsink with a thermal resistance below 10 °C/W to keep Tj under 125 °C at a 25 °C ambient. The non-repetitive surge rating of 63 A at 50 Hz (60 A at 60 Hz) covers capacitive inrush or short-duration overloads — the die absorbs that energy for one cycle without failing.
Active production — no LTB scramble needed
No end-of-life notice, no last-time-buy deadline to track. The ROHS3 compliance means it ships without any of the six restricted substances plus the four phthalates, so it passes EU material declarations without a waiver.