This part is a kind of semiconductor called C3927.
Function of this product has 2SC3927.
Manufacturers : Sanken electric
Image and pinout :

Some of the text within the PDF file :
2SC3927 Silicon NPN Triple Diffused Planar Transistor (High Voltage Switchihg Transistor) sAbsolute maximum ratings (Ta=25°C) Symbol VCBO VCEO VEBO IC IB PC Tj Tstg 2SC3927 900 550 7 10(Pulse15) 5 120(Tc=25°C) 150 –55 to +150 Unit V V V A A W °C °C Application : Switching Regulator and General Purpose (Ta=25°C) 2SC3927 100max 100max 550min 10 to 28 0.5max 1.2max 6typ 105typ V V MHz pF 20.0min 4.0max 3 1.05 +0.2 -0.1 5.45±0.1 B C E 5.45±0.1 0.65 +0.2 -0.1 1.4 sElectrical Characteristics Symbol ICBO IEBO V(BR)CEO hFE VCE(sat) VBE(sat) fT COB Conditions VCB=800V VEB=7V IC=10mA VCE=4V, IC=5A IC=5A, IB=1A IC=5A, IB=1A VCE=12V, IE=–1A VCB=10V, f=1MHz External Dimensions MT-100(TO3P) 5.0±0.2 15.6±0.4 9.6 2.0 1.8 4.8±0.2 2.0±0.1 Unit µA µA 19.9±0.3 V 4 [ ... ]
C3927 PDF Datasheet Download
