The TIP120 NPN Darlington power transistor is a commonly used medium power device that can handle up to 5A @ 60V.

These TIP120 NPN Darlington power transistors let you control quite a bit of power. They are good for up to 60V with a constant current of 5A or up to 8A peak.

The Darlington transistor architecture is actually composed of 2 transistors in an emitter-base follower configuration along with associated resistors in a single package with a BCE pin-out. This gives the transistor a much larger current gain which is useful in applications where current amplification or switching is required.

They can be used when you need to step up to an NPN transistor with more grunt than something like a PN2222 can deliver but don’t really need a big MOSFET. These are good for general purpose amplification and slower speed switching and are frequently used for driving motors, fans, high power LEDs and similar applications.

If using with an MCU, it is possible to drive the transistor directly from an output pin using a series resistor to limit current to safe levels.

Datasheet: https://www.onsemi.com/pdf/datasheet/tip120-d.pdf