This part is a kind of semiconductor called C3042.

Function of this product has 2SC3042.

Manufacturers : Sanyo Semiconductor Corporation

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Some of the text within the PDF file :

Ordering number:EN938B NPN Triple Diffused Planar Silicon Transistor 2SC3042 400V/12A Switching Regulator Applications Features · High breakdown voltage (VCBO≥500V). · Fast switching speed. · Wide ASO. Package Dimensions unit:mm 2022A [2SC3042] Specifications Absolute Maximum Ratings at Ta = 25˚C Parameter Collector-to-Base Voltage Collector-to-Emitter Voltage Emitter-to-Base Voltage Collector Current Collector Current (Pulse) Base Current Collector Dissipation Symbol VCBO VCEO VEBO IC ICP IB PC Tc=25˚C PW≤300µs, Duty Cycle≤10% 1 : Base 2 : Collector 3 : Emitter SANYO : TO-3PB Conditions Ratings 500 400 7 12 25 4 2.5 100 150 –55 to +150 Unit V V V A A A W W ˚C ˚C Junction Temperature Storage Temperature Tj Tstg Electrical Characteristics at T [ ... ]

C3042 PDF Datasheet Download