This part is a kind of semiconductor called KSE340.
Function of this product has High Voltage General Purpose Applications.
Manufacturers : Fairchild Semiconductor
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Some of the text within the PDF file :
KSE340 KSE340 High Voltage General Purpose Applications • High Collector-Emitter Breakdown Voltage • Suitable for Transformer • Complement to KSE350 1 TO-126 2.Collector 3.Base 1. Emitter NPN Epitaxial Silicon Transistor Absolute Maximum Ratings TC=25°C unless otherwise noted Symbol VCBO VCEO VEBO IC PC TJ TSTG Parameter Collector-Base Voltage Collector-Emitter Voltage Emitter-Base Voltage Collector Current Collector Dissipation (TC=25°C) Junction Temperature Storage Temperature Value 300 300 5 500 20 150 - 65 ~ 150 Units V V V mA W °C °C Electrical Characteristics TC=25°C unless otherwise noted Symbol BVCEO ICBO IEBO hFE Parameter Collector-Emitter Breakdown Voltage Collector Cut-off Current Emitter Cut-off Current DC Current Gain Test Condition IC = 1mA, IB = 0 VCB = 300 [ ... ]