Temperature fluctuations impacting MCP3428 readings?


I’m using the MCP3428 4-Channel 4-20mA 16-Bit Current Receiver with IoT Interface board to read the 4-20mA flow meter signal measuring natural gas flow to a flare. Since the flow meter is installed near the flare, ambient temperatures can become quite hot at ~135 degF. In the shop, I’m able to very precisely calibrate and read the 4-20mA signal, but on one particular device in the field, I was seeing about +2mA error as the devices temperature increased over 105 degF.

So my questions is - Are there any temperature compensations or temperature error mitigation features baked into this board?

I was able to recreate this issue on new boards in the shop as well.

One interesting thing - While reading all 4 channels under heat, channel 1 and 4 generally read low, while channels 3 and 4 read high. The average of all 4 readings generally is accurate.

There is on board temp comp on this unit. It’s a pulse analog to digital converter. You can look into MCP3428 datasheet, if there is any temp comp, it will be there.


Thanks for the quick reply @Anil_Bhaskar !!

Any other thoughts to why temp can be affecting readings? This seems to be a very repeatable problem. Also interestingly, CH1 and CH2, and CH3 and CH4 seem to have in inverse relationship. If CH1 is reading low, CH2 is reading high.

Here’s a screenshot with an 8mA signal at ~ 140 degF.

At lower temps, the error between the CH1 and CH2, or CH3 and CH4 is smaller:

This ADC can be used as single-ended and as diff ADC. which means ch1 and ch2 two are internally linked, and ch3 and 4 are internally linked. That could cause a strange relationship between 1 and 2.

Change your resolution to 12bit and sample rate to lowest and see how it does.

Is there anyway to change the setting to select single-ended or as diff ADC? Switching to 12-bit and reducing the sampling rate seemingly helped a bit with temperature variations, but resulted in an unacceptable drop in precision.

you are already using in single ended mdoe.

Any further recommendations explaining the strange relationship between CH1 and CH2, and how to get accurate readings from this board over the rated temperature range?