THD400 Transistor NPN

The THD400 is an NPN-type silicon power transistor (frequently used in Darlington configurations or high-fidelity audio output stages).

As older or specific electronic components can have variants depending on the manufacturer (e.g. STMicroelectronics, RCA, etc.), here are the typical and standard technical specifications associated with this part number:

Main Characteristics

• Polarity: NPN
• Material: Silicon (Si)
• Package: TO-3 (robust metal container for heatsink mounting) or plastic equivalents depending on the revision.

Limiting Electrical Parameters (at 25°C)

• Collector-emitter voltage (VCEO): ~ 400V (can vary up to 400V-500V in high-voltage versions).
• Collector-base voltage (VCBO): ~ 400V / 500V.
• Continuous collector current (IC): Typically between 8A and 15A (depending on the specific manufacturer).
• Total power dissipation (PD): Up to 100W - 125W (with a suitable heatsink).
• Transition frequency (fT): Generally optimised for low/medium frequency or switching applications (audio frequencies or power supplies).

Main Applications

• Power audio amplifiers.
• Switch-mode power supply (SMPS) circuits.
• Inverters and drivers for inductive loads.

Note: For a 100% secure and official datasheet, it is advisable to check the manufacturer logo printed on the physical component in your possession.