The FDMB3900AN from onsemi is a MOSFET with Continous Drain Current 7 A, Drain Source Resistance 23 milliohm, Drain Source Breakdown Voltage 20 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage 3 V. Tags: Surface Mount. More details for FDMB3900AN can be seen below.