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How to avoid the interference on sampling current signal when am26lv32 was working with mcu?

peikun zheng
Prodigy 40 points

Part Number: AM26LV32

When the differential signal imported in am26lv32, the interference on sampling current signal has emerged, whose frequency is 100Hz..

u15 is our part am26lv32 and its layout was as guiedline.

sch is as below.

current sampling is showing as below

  • 0
    Guru 320650 points

    The AM26LV32 is a purely digital device, and cannot change the values of ADC samples.

    This problem happens at the ADC (which you have not shown); probably noise from the power supply.

  • 0
    TI__Guru 53952 points

    Hi Peikun,

    As Clemens mentioned this seems to be coming from the ADC device - the 100Hz signal is not likely to originate from the driver as there isn't any "switching" in the driver except the actual data values.

    I do think it is most likely due to adding the ADC - the transceiver is most likely not causing the noise but other components in the system. 

    The one possible thing that may add some common mode noise is high ground loop currents - I don't think its the main culprit - but it could be adding to the problem. Please see below for RS-485 grounding that can reduce common mode noise:

    Please note that the grounding shown above can't be used in every system - but it could add to common mode noise on the line and maybe a partial solution. However I will stress that the ADC is probably the first place you should look at.

    Please let me know if you have any other questions!

    Best,

    Parker Dodson