The BUK9Y12-40E from Nexperia is a MOSFET with Continous Drain Current 36.7 to 52 A, Drain Source Resistance 8.8 to 24.1 milliohm, Drain Source Breakdown Voltage 40 V, Gate Source Voltage -15 to 15 V, Gate Source Threshold Voltage 0.5 to 2.45 V. Tags: Surface Mount. More details for BUK9Y12-40E can be seen below.