This post explains for the MOSFET.
The Part Number is K4115, 2SK4115.
The function of this semiconductor is 900V, 7A, N-channel MOSFET.
The package is TO-3P Type
Manufacturer: Toshiba Semiconductor
Preview images :
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Description
K4115 is Silicon N-Channel MOS Type Field Effect Transistor.
Features
1. Low drain-source ON resistance: RDS (ON) = 1.6 Ω (typ.)
2. High forward transfer admittance: ⎪Yfs⎪ = 5.0 S (typ.)
3. Low leakage current: IDSS = 100 μA (max) (VDS = 720 V)
4. Enhancement model: Vth = 2.0~4.0 V (VDS = 10 V, ID = 1 mA)
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Absolute Maximum Ratings (Ta = 25°C)
1. Drain to source voltage: VDSS = 900 V
2. Gate to source voltage: VGSS = ± 30 V
3. Drain current: ID = 7 A
4. Drain Power Dissipation: Pd = 150 W
5. Channel temperature: Tch = 150 °C
6. Storage temperature: Tstg = -55 to +150 °C
Applications:
1. Switching Regulator