The KFK4B40028NU from Nuvoton Technology is a MOSFET with Continous Drain Current 3.5 to 7.1 A, Drain Source Resistance 17.0 to 47 milli-ohm, Drain Source Breakdown Voltage 40 V, Gate Source Voltage -10 to 12 V, Gate Source Threshold Voltage 1.0 to 3.0 V. Tags: Chip. More details for KFK4B40028NU can be seen below.