The Si4431CDY from Vishay is a MOSFET with Continous Drain Current -9 A, Drain Source Resistance 26 to 49 milliohm, Drain Source Breakdown Voltage -30 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage -1 to -2.5 V. Tags: Surface Mount. More details for Si4431CDY can be seen below.