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Hey Guys! Hope you are doing well. I am here to keep updated with relevant information related to engineering and technology. Today, I’ll give you a quick read about 2N3906 Pinout and description, which is a PNP transistor and mainly used for low power amplification and switching purposes. Let's have a look at the basic properties of 2N3906:


Basics of 2N3906

  • This PNP transistor comes with three terminals, which are:
    1. Emitter.
    2. Base.
    3. Collector.
  • The 2N3906 contains three layers i.e. two P-doped layers which house an N-doped layer between them.
  • All three terminals are different in terms of doping concentration and size. The base is lightly doped and very thin in size, while the emitter is highly doped and houses the maximum current of the transistor. The collector is bigger than both terminals and is moderately doped.
  • This PNP transistor is a type of bipolar junction transistor where both electrons and holes are responsible for carrying out the conduction process; however, holes are the majority charge carriers and take the main part in the conduction.

Working of 2N3906

The 2N3906 is called a current-controlled device, where a small current at the base side is used to control a large current at the other terminals. No conduction is carried out unless the base of the transistor is applied with some bias voltage which allows the holes in the emitter side to move and flow toward the base terminal.

The PNP transistor is essentially two diodes joined back to back. It consists of two PN junctions i.e. emitter-base junction and collector-base junction. The emitter-base junction is forward biased and responsible for the conduction in the transistor and carries small resistance. The collector-base junction is reverse biased and takes no part in the conduction and carries maximum resistance.

The transistor will only conduct when the base terminal is kept negative with respect to the emitter and voltage at the base terminal is 0.7V less than the voltage at the emitter terminal.

The 2N3906 is mainly designed for low power and lower current applications. It is not an ideal choice for amplification and switching purposes as compared to the NPN transistor, this is because the latter comes with electrons as the major charge carriers and shows an ideal power requirement for the amplification process.

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