I am designing a liquid level sensing application with the following requirements:
- between PCB (sensor) and liquid, there is 1.5mm plastic, 0.5mm air, and 2.5mm plastic (the latter could be adjusted down)
- I need it to be precise and repeatable
- liquid and electronic are both floating (battery)
- height of container is 200mm
- desired resolution is about 5mm
Instead of having two sensor strips spanning the full height of the sensor, I thought it would be more noise resistant, and generally better to split the sensors in multiple smaller sensors.
I plan to stack up to 8 AD7746 on my sensor baord, for a total of 16 smaller sensor.
I will put a transistor on each chip VDD and have them ON one by one to avoid interference and I2C address collision.
My questions are:
- do you have any reference design, or design tips regarding the segmented sensor approach?
- any recommendation of sensor layout and size?
- any remark or general tips?
- recommendation on what component to use? I mentioned 8 AD7746, but I could also use like 2 AD7147.
Added note about AD7147
[edited by: kuon at 4:08 AM (GMT -5) on 19 Feb 2021]