I have a question regarding ULN2803A or 497-2356-5-ND.
I am planning to use a MCU to turn on and turn off a relay.
The MCU is capable of giving 3.3V output. Will this be enough to turn on ULN2803A transistor ? Or does it have to be 5V ?
Thank you

Welcome to the forum!

The data sheet shows that the “3A” version has a turn on range of 2.4V to 3V @ 200mA to 300mA so it should work well with a 3.3V micro.