This part is a kind of semiconductor called K2399.

Function of this product has Field Effect Transistor.

Manufacturers : Toshiba Semiconductor

Image and pinout :

Some of the text within the PDF file :

2SK2399 TOSHIBA Field Effect Transistor Silicon N Channel MOS Type (L2−π−MOSV) 2SK2399 Chopper Regulator, DC−DC Converter and Motor Drive Applications Unit: mm l 4 V gate drive l Low drain−source ON resistance : RDS (ON) = 0.17 Ω (typ.) l High forward transfer admittance : |Yfs| = 4.5 S (typ.) l Low leakage current : IDSS = 100 µA (max) (VDS = 100 V) l Enhancement−mode : Vth = 0.8~2.0 V (VDS = 10 V, ID = 1 mA) Maximum Ratings (Ta = 25°C) Characteristics Drain−source voltage Drain−gate voltage (RGS = 20 kΩ) Gate−source voltage Drain current DC (Note 1) Pulse (Note 1) Drain power dissipation (Tc = 25°C) Single pulse avalanche energy (Note 2) Avalanche current Repetitive avalanche energy (Note 3) Channel temperature Storage temperature range Symbol [ ... ]

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