What Is the 2N2222? NPN Transistor: Pinout, Specs and Uses
The 2N2222 (and 2N2222A) is a classic NPN bipolar transistor (BJT). It is used for fast switching and small-signal amplification and can carry up to 800 mA (V_CEO 40 V). The pinout varies by package: TO-92 (P2N2222A) is usually E-B-C and the original TO-18 metal can differs — verify the datasheet before wiring.
The 2N2222 (and its improved version, the 2N2222A) is one of the most classic NPN bipolar transistors (BJTs). It has been used for decades for fast switching and small-signal amplification. For the concept, see what is a transistor · what is a BJT.
What is the 2N2222 used for?
It switches (drives) loads such as a relay, a group of LEDs, a small motor or a buzzer from a microcontroller pin, and amplifies small signals. With up to 800 mA and fast switching it is a general-purpose "do-everything" transistor.
2N2222 pinout — it VARIES by package (watch out)
This is the most common source of mistakes:
- TO-92 plastic (P2N2222A / PN2222): with the flat face toward you, left to right it is usually E – B – C (Emitter, Base, Collector).
- TO-18 metal can (original 2N2222): the layout is different and is oriented by the tab.
⚠️ Before wiring, always verify the pinout in the datasheet of your exact part — TO-92 and TO-18 are not the same.
Key electrical specifications (2N2222A)
| Parameter | Typical value |
|---|---|
| Type | NPN BJT |
| VCEO (collector-emitter) | 40 V |
| IC (max collector current) | 800 mA |
| hFE (current gain) | ~100 – 300 |
| fT (transition frequency) | ~250–300 MHz |
Using it as a switch
The base is driven through a base resistor (typically 1 kΩ); provide enough base current so that IB ≈ IC / hFE. With inductive loads (relay/motor), put a freewheel diode (e.g. the 1N4148/1N4007) across the collector. To check it: test a transistor with a multimeter.
2N2222 equivalents and alternatives
- 2N3904: a close relative with lower current (200 mA).
- BC547: the European equivalent (different pinout — CBE).
- 2N2907: the PNP counterpart.
- PN2222 / P2N2222A: the TO-92 versions.
Find it in our catalog
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