My question is how to separate the 2 grounds. I want to separate the ground for the high-power LDO from the ground for the low-power LDO. I need to use an optocoupler at 24V, and I want to isolate it from my ESP32. One issue I encountered was that the grounds for the optocoupler and the ESP32 were c…

[image] leansolution: Can surges goes to esp32 from Collector/Emitter to base of transistor? No but for extra protection you can put a TVS diode across the transistor from collector to emitter and pick a transistor with a high Vce rating

[image] leansolution: Looking for cheapest option without compromising reliability. It not clear what you mean by "reliability". Why do you think that have two grounds is more reliable than one?

By reliability, I am referring to longevity of MCU - not being damaged by surges/spike & other common events in industrial automation systems. Which is why I opted to use photocouplers for my MCU IOs, but didn't' know common GND still could cause an issue. My 3.3V circuit is powered through an LDO …

I would like to add, the main 24V supply has reverse polarity protection with a diode on GND. The only risk I can understand is the internal 24V event passing through GND system & damaging the MCU. I can separate the 3.3V GND traces/pads from rest of the system GND, but it would still have a common …

[image] leansolution: Which is why I opted to use photocouplers for my MCU IOs, but didn't' know common GND still could cause an issue. There is no point in using optocouplers if the grounds are common. You must also have an isolated power supply. Please post your entire schematic so we can …

For the third time no diode in GND! It serves no purpose and will just create ground problems.

[image] leansolution: Is my MCU protected? Protected from what? What do you think will happen?

damage due to Surges/Transient/Spikes

First you need to identify the source of these surges/transients/spikes and then try to eliminate them. So where do these surges/transients/spikes come from?

Only source of surges/Spikes is from Relay coil circuit to transistor . Can surges goes to esp32 from Collector/Emitter to base of transistor?

Separate out Grounds fom eachother

Projects General Guidance

grb May 26, 2025, 4:36pm 25

Could potentially be higher due to non-ideal diode behavior, I think.

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Separate out Grounds fom eachother

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