4-channel 4-20ma mcp3428 raw value variance

Hardware
1

Hi, we bought a bunch of the 4-channels 4-20mA MCP3428 cards a while ago but only managed to connect them up for testing recently. We notice that most cards have at least 1 channel that has a very different raw value varying from 1.4% to as high as 3.6% (usually higher raw value). The channel that has variance is different between different cards, hence its unlikely to be a script issue.

We retested by changing addresses and the same difference appeared on the same physical card and same channel on that card. Is there a way to adjust it on the hardware rather than manually calibrating every channel and card in the chain (upto to 8 receiver cards in one I2C chain)?

Also do you think this variance will change over time, eg. months, so that we may have to re-calibrate the receiver cards from time to time?

Thank you.

2

Hi,
the error comes due to parts tolerance. As most analog devices it needs be tuned using the software.

once a channel is calibrated it does not need to be calibrated in future.

Thanks