The TN3050H-12GY-TR from STMicroelectronics is a Silicon Controlled Rectifier with Breakover Voltage 1200 V, Breakover Current 300 A, Gate Trigger Voltage 1.3 V, Gate Trigger Current 0.05 A, Temperature Operating Range -40 to 150 Degree C. Tags: Surface Mount. More details for TN3050H-12GY-TR can be seen below.