Boron and MCP3428 4-Channel 4-20mA Resolution and sample rate

Hi All,
I am using MCP3428 with a Boron to get data from 4-20mA vibration sensor, sensor range 0-50 mm/s. I did find my code (the loop it takes 2.97 sec) to process 1 sample of date, I am trying to find the what is the resolution of my circuit and what’s the maximum sample rate.

I can tell the MCP3428 is 16 bit, but I still don’t know how to calculate the ADC resolution (Boron + MCP) and how much ADC resolution do I really need for the vibration sensor to get a proper data that i can rely on for vibration analysis?

Thank you

The datasheet for the MCP3428 says it’s 15 samples per second at 16-bit, though there will likely be some additional overhead that lowers the effective samples per second.

The part you need to be careful for with resolution, however, is how the 4-20mA is biased. The MCP3428 using the internal reference voltage is ±2.048V. However, depending on the 4-20mA conversion circuitry, it might only be using positive voltages, which means you start out at 15 effective bits because negative values won’t be used. The other is what range the conversion circuitry is set to. Often, it’s not full range where 20mA = 2.048V because if there was an overcurrent situation it could damage the ADC. So you might lose some resolution for the margins. But all of this is dependent on your particular 4-20mA converter.


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