The 2N2222AL is a general-purpose NPN bipolar junction transistor from Microchip Technology, packaged in a TO-206AA / TO-18-3 metal can with through-hole leads. Rated for a collector-emitter breakdown voltage of 50 V and a continuous collector current of 800 mA, it dissipates up to 500 mW — figures that define its switching and amplification envelope in low-to-medium power circuits. The DC current gain (hFE) is a minimum of 100 at 150 mA collector current with Vce = 10 V, providing consistent gain margin for driver and relay-coil applications. Vce saturation is specified at 1 V maximum with a base current of 50 mA driving 500 mA collector current — this saturation voltage governs the on-state power loss in switching service.
Temperature range and leakage performance
Operating junction temperature spans -65°C to 200°C, a military-grade range that suits avionics, downhole instrumentation, and engine-bay electronics where ambient extremes exceed commercial limits. Collector cutoff current is a maximum 50 nA at rated voltage — this low leakage keeps the transistor firmly off in high-impedance bias networks and battery-powered sleep circuits where every microamp counts.
The TO-18 metal can (supplier device package TO-18) is a hermetic, three-lead through-hole package with the collector connected internally to the case — the metal envelope acts as a heat path and an electrical node, so the PCB layout must account for case potential.