12 A RMS SCR for phase-control and AC switching
The STMicroelectronics TYN412RG is a standard-recovery SCR (silicon-controlled rectifier) in a TO-220-3 through-hole package, rated for 400 V off-state voltage and 12 A RMS on-state current. It is designed for medium-current phase-control applications such as motor speed controls, lighting dimmers, heating regulators, and AC power switching where a robust, cost-effective thyristor is needed. With an 8 A average on-state current (It(AV)) and a non-repetitive surge capability of 145 A at 60 Hz, the TYN412RG handles continuous loads up to about 1.8 kW on a 230 VAC line while surviving the inrush from incandescent lamps or motor starts.
Gate drive and thermal headroom
The gate trigger current (Igt) is 15 mA maximum, with a maximum gate trigger voltage of 1.3 V. This sensitivity allows direct drive from a standard optocoupler or a low-power transistor without an intermediate driver stage, simplifying the control circuit. Holding current (Ih) is 30 mA maximum, ensuring the SCR latches on once triggered and does not drop out prematurely under light load. The off-state leakage is just 5 µA, minimising power loss in the blocking state. The on-state voltage (Vtm) is 1.6 V maximum at rated current, which sets the conduction loss floor.