2 channel Frontend with over/under-voltage protection

[charlee]

Hi all, I created a simulation of a 2 channel Frontend.
The design is based on Design 3 example.
I only adjusted the resistor values based on what I have, and used the unused op-amp for the second channel.
This way, a single LM324N is sufficient.

In the design, channel 1 and channel 2 share the same Vref and the same op-amp for over-voltage protection.
My understanding is that, since the output of an ideal op-amp is an ideal voltage source,
it should be possible to connect multiple loads to the output of OP1 without impacting each other.

In the simulation, I used two AC sources with diferent frequencies (2kHz vs. 1.37kHz)
and it turned out that Vref only has negligible changes.
And ADC1 and ADC2 do not affect each other.

Please let me know if I am completely wrong!

[fhdm-dev]

Looks good to me! The disadvantage of using the same Vref op-amp for both channels is that the channels can't have different input voltage ranges - but if that's not an issue for you then it makes sense to use the same op-amp for both.