This post explains for the MOSFET.
The Part Number is K8A55DA, TK8A55DA.
The package is TO-220 Type.
The function of this transistor is 550V, 7.5A, N-Channel MOSFET.
Manufacturer: Toshiba
Preview images :
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Description
This is Silicon N Channel MOS Type Field Effect Transistor.
Features
1. Low drain-source ON-resistance: RDS (ON) = 0.9 Ω(typ.)
2. High forward transfer admittance: |Yfs| = 3.0 S (typ.)
3. Low leakage current: IDSS = 10 μA (max) (VDS = 550 V)
4. Enhancement mode: Vth = 2.0 to 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 = 550 V
2. Gate to source voltage: VGSS = ± 30 V
3. Drain current: ID = 7.5 A
4. Drain Power Dissipation: Pd = 40 W
5. Channel temperature: Tch = 150 °C
6. Storage temperature: Tstg = -55 to +150 °C
Applications:
1. Switching Regulator