For a PLC like application I have to design a module that measures temperature (PT1000, 2-wire), pH and EC (2 electrode kind).
I'm using CN0398 and CN0359 as reference material.
The pH and temperature conditioning circuits are known to me but an EC measurement is new.
Due to the tight space requirements I would like to use the AD7779.
As I see it this would negate the need for the additional S&H amplifiers as used in CN0359 due to the AD7779' simultaneous sampling.
I'm I correct in this assumption? Do you see some issues with this approach?
The additional 50/ 60Hz filtering can be done in software.
Apologies. This was missed. I would recommend to use AD7124-8 for your system as it has all the building blocks required for your sensors. We have CN0411 that you could also use as your reference circuit…
Is this to generic a question?
I'm looking for some advice about the option to use the AD7779 instead of the additional S&H circuits for EC impedance determination.
Apologies. This was missed. I would recommend to use AD7124-8 for your system as it has all the building blocks required for your sensors. We have CN0411 that you could also use as your reference circuit, it still uses the S&H circuit technique but the circuit is much simplified as it is designed for 2-wire conductivity cell. However, I would still recommend to ask someone from the Reference Circuit as they are more familiar with the circuit and application design.
Thanks for your advice. I'll also ask on the reference circuit forum.