This part is a kind of semiconductor called BF421.

Function of this product has High Voltage Transistors(PNP Silicon).

Manufacturers : ON Semiconductor

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BF421, BF423 High Voltage Transistors PNP Silicon Features • These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant MAXIMUM RATINGS Rating Symbol BF421 BF423 Unit Collector −Emitter Voltage Collector −Base Voltage Emitter −Base Voltage Collector Current − Continuous Collector Current − Peak Total Device Dissipation (Note 1) @ TA = 25°C Derate above 25°C VCEO VCBO VEBO IC ICM PD −300 −250 −300 −250 −5.0 −500 100 830 6.6 Vdc Vdc Vdc mAdc mA mW mW/°C Operating and Storage Junction Temperature Range TJ, Tstg −55 to +150 °C THERMAL CHARACTERISTICS Characteristic Symbol Max Unit Thermal Resistance, Junction−to−Ambient RqJA °C/W 150 Thermal Resistance, Junction−to−Lead RqJL °C/W 68 Stresses exceeding Maximum Rat [ ... ]

BF421 PDF Datasheet Download