2N2222 Pinout Configuration
| Pin Number | Pin Name | Description |
| 1 | Emitter | Current Drains out through emitter |
| 2 | Base | Controls the biasing of transistor |
| 3 | Collector | Current flows in through collector |
Features:-
- Advanced process technology
- Low error voltage
- Fast switching speed
- Full-voltage operation
- High power and current handling capability
Detailed Specifications:-
| Transistor Polarity | NPN |
| Collector-Base Voltage (VCBO) | 75V |
| Collector-Emitter Voltage (VCEO) | 40V |
| Emitter-Base Voltage (VEBO) | 6V |
| Continuous Collector Current (IC) | 0.6A |
| Collector-Base Capacitance (CCBO) | 8pF |
| Transition Frequency (fT) | 300MHz |
| DC Current Gain (hFE) | 300 |
| Operating Temperature Range | -65 – 175°C |
| Power Dissipation (PD) | 1.8W |
Note: Complete Technical Details can be found in the 2N2222A datasheet, given at the end of this page.
2N2222 Brief Description
2N2222 is an NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at the ground and will be closed (Forward biased) when a signal is provided to the base pin. 2N2222A has a gain value of 110 to 800, this value determines the amplification capacity of the transistor. The maximum amount of current that could flow through the Collector pin is 800mA, hence we cannot connect loads that consume more than 800mA using this transistor. To bias a transistor we have to supply current to the base pin, this current (IB) should be limited to 5mA.
When this transistor is fully biased, it can allow a maximum of 800mA to flow across the collector and emitter. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (VCE) or Base-Emitter (VBE) could be 200 and 900 mV respectively. When the base current is removed the transistor becomes fully off, this stage is called the Cut-off Region, and the Base Emitter voltage could be around 660 mV.
Where to use 2N2222
The 2N2222 transistor is very much similar to the commonly used NPN transistor BC547. But there are two important features that distinguish both. 2N2222 can allow collector current up to 800mA and also has a power dissipation of 652mW which can be used to drive larger loads than compared with BC547.
So if you looking for an NPN transistor that could switch loads of higher current, then 2N2222 might be the right choice for your project.
How to use 2N2222
This transistor like all can be used either as a switch or as an amplifier. The Base-Emitter voltage of this transistor is 6V so you just have to supply this voltage across the base and emitter of the transistor to induce a base current into the transistor. This transistor will make it forward-biased and thus close the connection between the collector and emitter. However, one important thing to notice is the Base resistor a.k.a current limiting resistor. As the name suggests this resistor will limit the current flowing through the transistor to prevent it from damaging. The value for this resistor can be calculated using the formula
RB = VBE / IB
To make things simple, I have shown a simplified circuit to make a transistor switch. In actuality circuit modifications might be required. I have used a base voltage of 5V and a value of 1K as the current limiting resistor.
Note that the motor here draws about 500mA from the 12V power source, since the 2N2222 has a collector current rating up to 800mA this circuit is possible had it been a BC547 the transistor should have been burnt.
Applications
- Can be used to switch high-current (up to 800mA) loads
- It can also be used in various switching applications.
- Speed control of Motors
- Inverter and other rectifier circuits
- Can be used in Darlington Pair.
