I have data from an NTC and RTD that I need to pass over an isolation.
What I am thinking of doing a normal voltage divider for both and then turning this voltage into a duty cycle or frequency signal to pass through a digital optocoupler. Probably looking at about 10kHz
In designing this circuit money is my least concern, but footprint (both height and area) and accuracy are my main requirements. I need it to be very accurate and and I need the components height less than 2.5mm. So for resistors, caps, NTC and RTD I'm using 0603 or 1005 SMD.
I have been looking at LTC6992 (
https://www.analog.com/media/en/technical-documentation/data-sheets/LTC6992-1-6992-2-6992-3-6992-4.pdf)
I like this chip, it's easy to use, small footprint, but I worry it will not be accurate enough. It says plus minus 4.5% accuracy in the datasheet. It is also only 0.1-0.9V control voltage so I think it makes my readings from NTC and RTD more susceptible to noise because I have to lower the sensing current to get it to this level
Are there any other ICs like this, or would I be better off trying to find op amps in small footprints - or would to do it all on a small micro controller like ATTINY85 by better?