Power Transistor BU208D NPN, 15A TO-3

Power Transistor BU208D NPN, 15A TO-3

Transistors
TRBU208D
Part.No: BU208D
€2.95
Last items in stock
Immediate Dispatch

The BU208D is a high-voltage NPN power transistor in a TO-3 package, designed for Line Output (LOPT) switching in television deflection circuits. The integrated snubber diode and base-emitter resistor make it a complete, ready-to-use solution for demanding high-frequency switching applications.

 

BU208D Power Transistor – Integrated Damper Diode for LOPT Applications

The BU208D is a high-voltage NPN power transistor with an integrated snubber diode and base-emitter resistor, delivering robust performance in Line Output (LOPT) and flyback switching applications. Its monolithic design eliminates the need for external protection components, making it an industry-standard choice for television deflection circuits and high-frequency power switching.

Functions & Applications

  • Integrated Snubber Diode: Built-in collector-emitter diode (with damper function) protects against reverse voltage spikes during switch-off, eliminating the need for external protection.
  • Base-Emitter Resistor: Approximately 40–50Ω internal resistor ensures stable biasing and simplified drive circuitry.
  • TO-3 Metal Package: Excellent heat dissipation via large metal mounting surface; easy to bolt to a heatsink.
  • High-Voltage Switching: Rated for demanding LOPT (Line Output Transformer) applications in consumer and professional TV deflection circuits.
  • All-in-One Integration: Monolithic design reduces component count and simplifies PCB layout for flyback converters and high-frequency supplies.

Technical Specifications

ParameterValue / Specification
Transistor TypeBJT (Bipolar Junction Transistor)
Polarity / ChannelNPN
Package / CaseTO-3
Max Collector-Emitter Voltage (Vceo)1500V
Max Collector Current (Ic)15A
Power Dissipation (Pd)150W (with heatsink)
Integrated Base-Emitter Resistor~40–50Ω
Mounting TypeBolt-Down (TO-3 metal case)

Frequently Asked Questions

Q: Why does BU208D show a near-short between B-E and reverse conductivity on C when tested with a multimeter?
A: The internal 40–50Ω base-emitter resistor causes low resistance reading; the integrated snubber diode produces the reverse-conduction indication. This is normal and expected behavior for a damper-equipped transistor. Use an ohmmeter with diode-test mode or an ESR meter for accurate verification.

Q: Can I use BU208D as a direct replacement for the standard BU208?
A: Yes, the BU208D (with damper diode) is a plug-compatible upgrade to the BU208 and often preferred because the integrated protection diode simplifies circuit design and improves reliability in LOPT applications.

Notes

Vintage/NOS stock: specialized LOPT transistor from television era. Requires adequate heatsinking; integrated snubber diode changes multimeter behavior—do not confuse with actual component failure.

Note: Price refers to one (1) piece. The component is shipped in bulk without individual packaging.

Transistor Type
BJT (Bipolar Junction Transistor)
Transistor Polarity / Channel
NPN
Transistor Case Style
TO-3
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