The STB23NM50N from STMicroelectronics is a MOSFET with Continous Drain Current 17 A, Drain Source Resistance 162 to 190 Milliohm, Drain Source Breakdown Voltage 500 V, Gate Source Voltage - 25 to 25 V, Gate Source Threshold Voltage 2 to 4 V. Tags: Surface Mount. More details for STB23NM50N can be seen below.