EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: AdamSparky on May 15, 2013, 12:48:15 pm
-
I have only just started learning to use optocouplers to provide circuit isolation.
I would like to use an optocoupler to protect my microcontroller from the outside world, everything is run from the one power supply as per the attached circuit. I have both sides of the optocoupler attached to a common ground, this feels wrong, but don't know how it should be done.
How is this situation usually handled?
-
Ideally you want a separate supply, otherwise all you need is a simple one transistor inverter or a protected voltage divider into a buffer chip. You are negating the use of the optocoupler doing what you did.
-
There are reasons why people do it - some covered in this thread -
www.eevblog.com/forum/projects/design-microcontroller-circuit-for-industrial-noisy-environment/msg209648/#msg209648 (https://www.eevblog.com/forum/projects/design-microcontroller-circuit-for-industrial-noisy-environment/msg209648/#msg209648)
In the simplest case, it offers a 2nd level of protection. Blowing up / then repairing an opto is a heck of a lot easier
than blowing up an MPU - in which case everything is dead.