The TSM5055DCR (Q1) from Taiwan Semiconductor is a MOSFET with Continous Drain Current 38 A, Drain Source Resistance 8.8 to 14.9 milliohm, Drain Source Breakdown Voltage 30 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage 1.2 to 2.5 V. Tags: Surface Mount. More details for TSM5055DCR (Q1) can be seen below.