27. Transistor Application

Question.1

A microcontroller GPIO pin can source or sink maximum 20 mA.
A relay coil requires 80 mA at 12 V.

The following transistor is considered from Digi-Key:

Digi-Key Part Number: 2N2222A-ND

Is this transistor a correct selection for driving the relay, and why?

transistor-relay-circuit

Yes, because the relay current is less than the transistor’s maximum rating
Yes, because 2N2222A is a commonly used transistor
Yes, because the transistor allows the GPIO to control higher current using base drive
No, because GPIO pins cannot control transistors

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