50 V / 800 mA NPN — the TO-18 workhorse
The 2N2222AE4 is the through-hole TO-18 (TO-206AA) variant of the industry-standard 2N2222 NPN transistor from Microchip Technology. Rated for 50 V collector-emitter breakdown and 800 mA continuous collector current, it handles general-purpose switching and amplification in a hermetically sealed metal can.
Thermal envelope and gain at operating point
The metal-can package conducts heat to the board or heatsink clip more effectively than a plastic TO-92 — useful when the transistor sits near a hot regulator or in a cramped enclosure. DC current gain (hFE) is specified at 100 minimum at Ic=150 mA and Vce=10 V — this is the typical switching point for driving relays or small solenoids. Vce saturation is 1 V max at 50 mA base drive and 500 mA collector current, keeping conduction losses manageable at moderate duty cycles.
Active production, bulk pack, multi-source reality
It ships in bulk (tube or bag), not tape-and-reel, which suits bench stock, repair depots, and low-to-medium volume builds where reel packaging adds waste. The base part number 2N2222 is a JEDEC-registered device produced by multiple manufacturers. The Microchip TO-18 variant is interchangeable with the same package from other qualified sources, though the AE4 suffix is Microchip-specific.