Jim, this is related to my other thread (24V with transistor to power the relay). This relay will carry 220V AC. Relay switching could cause 24V spikes/transients & I want to protect my MCU 3.3V circuit at an industrial grade reliability.
You had suggested using two isolated power sources in the other thread, which is complicates my design. Currently I am using 24V main supply and using LDO to get my 3.3V. I am curious if I could separate my 3.3V GND circuit & use a diode at GND common point (LDO) to protect reverse current/spikes from 24V circuit.
I will not be isolated, but will that be good enough protection for a reliable system? My other option will be to use a step down transformer from 24V to 3.3 V, which will give me a separate ground , but definitely increase cost & I want to avoid it.