This part is a kind of semiconductor called 4N65.

Function of this product has 650 Volts N-CHANNEL POWER MOSFET.

Manufacturers : Unisonic Technologies

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Some of the text within the PDF file :

UNISONIC TECHNOLOGIES CO., LTD 4N65 4A, 650V N-CHANNEL POWER MOSFET „ DESCRIPTION 1 Power MOSFET 1 TO-220 TO-220F The UTC 4N65 is a high voltage power MOSFET designed to have better characteristics, such as fast switching time, low gate charge, low on-state resistance and have a high rugged avalanche characteristic. This power MOSFET is usually used in high speed switching applications including power supplies, PWM motor controls, high efficient DC to DC converters and bridge circuits. 1 1 TO-220F1 TO-220F2 „ FEATURES 1 * RDS(ON) = 2.5Ω @VGS = 10 V * Ultra Low Gate Charge ( typical 15 nC ) * Low Reverse Transfer Capacitance ( CRSS = Typical 8.0 pF ) * Fast Switching Capability * Avalanche Energy Specified * Improved dv/dt Capability, High Ruggedness 1 TO-251 TO-252 „ S [ ... ]

4N65 PDF Datasheet Download