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2N2222

The 2N2222, also known as the PN2222 and commonly referred to as the 'quad two' transistor, is a small, common NPN BJT transistor used for general purpose low-power amplifying or switching applications. It is designed for low to medium current, low power, medium voltage, and can operate at moderately high speeds.

It is a 1 amp, 50 volt, 300 milliwatt transistor capable of operating up to 100 MHz, with a beta of at least 100. It's used in a variety of analog amplification and switching applications.

It is available in a variety of small through-hole and surface mount packages including TO-92, SOT-23, and SOT-223.

When biased backwards, and with no connection to the base, 2N2222A are rumored to have negative resistance avalanche properties. Similar to a tunnel or lambda diode, perhaps useful for simple oscillator circuits. This would be an abuse of the component never intended by the manufacturer.

A 2N2907 is a complementary (PNP) transistor for the 2N2222. The 2N3904 is an NPN transistor that can only switch one tenth the current of the 2N2222 but has otherwise similar characteristics.

External links

• Datasheet for Philips Semiconductor's 2N2222 (PDF)
• Datasheet for Fairchild Semiconductor's equivalent PN2222 (PDF)