Question

Why do we need a ULN2803 in driving a relay?

(a) for switching a motor

(b) for increasing the current

(c) for increasing the power

(d) for switching the voltage

I had been asked this question during an internship interview.

My question is based upon Interfacing with Motors topic in chapter 8051 Microcontroller of Microcontroller

Answer 1

The correct choice is (b) for increasing the current

For explanation I would say: We need a ULN2803 for driving a relay because the relay coil requires 10mA or more current to be energized. If microcontroller pins are not able to provide sufficient current to drive relays then we need ULN2803 for driving relays.