2N3906 Transistor
From Jim Julian Wiki
2N3906 Transistor
The 2N3906 is a popular PNP bipolar junction transistor (BJT) used for general-purpose low-power amplification and switching applications. It is commonly paired with the 2N3904 NPN transistor and is known for its reliability, affordability, and availability.
General Information
- Type: PNP Bipolar Junction Transistor
- Application: General-purpose, switching, and amplification
- Packaging: TO-92 (plastic)
Key Features
- Complementary to the 2N3904 (NPN)
- Low saturation voltage
- Fast switching speed
- Suitable for a wide range of analog and digital applications
Specifications
| Parameter | Symbol | Value |
|---|---|---|
| Maximum Collector-Emitter Voltage | VCEO | –40 V |
| Maximum Collector-Base Voltage | VCBO | –40 V |
| Maximum Emitter-Base Voltage | VEBO | –5 V |
| Maximum Collector Current | IC | –200 mA |
| Power Dissipation | Ptot | 625 mW |
| Transition Frequency | fT | 250 MHz |
| DC Current Gain (hFE) | hFE | 100–300 |
Pin Configuration
The 2N3906 transistor has three pins in the TO-92 package:
- Pin 1: Emitter
- Pin 2: Base
- Pin 3: Collector
(Note: Viewed with flat side facing you.)
Applications
The 2N3906 is commonly used in:
- Low-power signal amplification
- General-purpose switching
- Analog circuits
- Complementary push-pull amplifier designs (with 2N3904)
- LED control circuits
Circuit Example
Basic PNP Switching Circuit A 2N3906 can be used to switch a load:
- Connect the emitter to the positive voltage supply.
- Connect the collector to one end of the load; the other end of the load goes to ground.
- A base resistor is connected between the base and ground (or a logic signal).
- When the base is pulled low (below the emitter potential by ~0.7 V), the transistor turns on.
Advantages
- Low cost and widely available
- Ideal for negative-side switching
- Fast switching response
- Useful in complementary pair configurations
Limitations
- Limited to low-current applications
- Not suitable for high-voltage or high-power loads
Common Alternatives
- PN2907 (higher current rating)
- BC558 (European equivalent)
- 2N2906
Complementary Pair
- The 2N3906 is the PNP complement of the NPN 2N3904.
