The P011xx is a high-sensitivity, high-immunity SCR from STMicroelectronics. It has voltage ratings of 400 V and 600 V and can operate with trigger currents in the range of 0.5 µA to 25 µA. It is suitable for applications where the available gate current is limited, such as ground fault circuit interruptors, pilot circuits in solid state relays, standby mode power supplies, smoke and alarm detectors.