The FQB4N80 from onsemi is a MOSFET with Continous Drain Current 3.9 A, Drain Source Resistance 2800 to 3600 milliohm, Drain Source Breakdown Voltage 800 V, Gate Source Voltage -30 to 30 V, Gate Source Threshold Voltage 3 to 5 V. Tags: Surface Mount. More details for FQB4N80 can be seen below.