Other Parts Discussed in Thread: ADS127L11, ADS131A04, ADS1271, ADS127L01, ADS127L21, TPS7A20
Tool/software:
For a new project we are using capacitive sensors for very accurate height measurements (3mm range with nanometer resolution). The cap sensor amplifiers have a current loop output (4..20mA) related to the height (0..3mm) and we want to use that for height measurements by our motion controller
I have to design a current loop to voltage converter because we want to read the sensor info with a 20 or 24 bit SPI ADC with an update rate of 20kHz. I already got some info from the Amplifiers forum wrt the current loop to voltage converter but for the ADC choice they referred to the Data Converters forum. Besides the exact implementation for the current loop to voltage converter also depends on the ADC choice (inpput range).
Do you have any suggestion which ADC devices are suitable ( 20-or 24 bit ADC with SPI interface and fast conversion time)? And maybe an evaluation board or a design example that could work for this application? With these we could already start some testing together with our software engineers.
When I look in the ADC selector for 20 bit or higher ADCs with fast data rate (>250ks/s) and SPI interface I can only find the 24 bit ADS127L11 or the 20 bit ADS8900B. With 20kHz we have 50 usec cycle time but within this time that data has to be sampled and converted and ready for the next conversion cycle. .Besides we want to read the data via BISS interface so we have to transfer the SPI data to BISS protocol which will also take some time (we already found a chip that can do this task). So therefore I think we need an ADC that will take not too much time for sampling and conversion? Or do you think we can use an ADC with a lower sampling rate?
Best Regards
Chris