Part Number: 2N3905
Function: 40V, 0.2A, PNP Transistor
Package: TO-92 Type
Manufacturer: Fairchild Semiconductor, On semicondcutor
Image and Pinouts:
The 2N3905 is 40V, 0.2A, PNP Silicon Planar Epitaxial Transistor.
This device is designed for use as general purpose amplifiers and switches requiring collector currents to 100 mA.
A PNP transistor is a type of bipolar junction transistor (BJT) with a different structure and polarity compared to an NPN transistor.
Here are characteristics of PNP transistors:
1. Structure: A PNP transistor has a sandwich-like structure, consisting of a thin P-type layer (base) sandwiched between two N-type layers (emitter and collector).
2. Polarity: In a PNP transistor, the majority charge carriers are holes, which flow from the emitter to the collector. The emitter is negative relative to the base, and the collector is positive relative to the base.
3. Current flow: When a small current is applied to the base terminal, it allows a much larger current to flow from the emitter to the collector. This is called amplification or gain, and it makes the PNP transistor useful as an electronic switch or amplifier.
4. Voltage levels: The voltage levels in a PNP transistor are opposite to those in an NPN transistor. In a PNP transistor, the base-emitter junction is forward-biased and the collector-base junction is reverse-biased.
5. Biasing: PNP transistors are biased in the opposite direction to NPN transistors. To turn on a PNP transistor, the base must be more negative than the emitter, and to turn it off, the base must be more positive than the emitter.
Absolute maximum ratings ( Ta=25°C )
1. Collector to Base Voltage: Vcbo = 40 V
2. Collector to Emitter Voltage: Vceo = 40 V
3. Emitter to Base Voltage: Vebo = 5 V
4. Collector Current: Ic = 200 mA
5. Total Dissipation: Pd =625 mW
6. Junction Temperature: Tj = 150°C
7. Storage Temperature: Tsg = -55 ~ +150°C