The Si4943CDY from Vishay is a MOSFET with Continous Drain Current 8 A, Drain Source Resistance 16 to 33 milliohm, Drain Source Breakdown Voltage -20 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage -1 to -3 V. Tags: Surface Mount. More details for Si4943CDY can be seen below.