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AMC1204: AMC1204B Current sense Error

Part Number: AMC1204

Hi team,

  My customer is using AD7401 from ADI and AMC1204B for performance comparison in below SCH:

  However, when using AMC1204B, the error is large(>10%), while ADI part is small. Below data is captured for your reference. Can you help check if the SCH/ parameter is OK? Any angles we should look into? Thanks.

I_load(A): actual current

AD data

I_MCU(A): converted from digital data

error 

-4

23656

-4.459961

-10.313%

-3

25934

-3.347656

-10.385%

-2.5

27065

-2.795410

-10.568%

-2

28224

-2.229492

-10.293%

-1

30456

-1.139648

-12.254%

-0.5

31613

-0.574707

-12.999%

-0.2

32320

-0.229492

-12.851%

-0.1

32542

-0.121094

-17.419%

0

32790

0.000000

 

0.1

33038

0.121094

-17.419%

0.2

33270

0.234375

-14.667%

0.5

33952

0.567383

-11.876%

1

35120

1.137695

-12.103%

2

37381

2.241699

-10.782%

3

39635

3.342285

-10.241%

4

41923

4.459473

-10.303%

 

Regards,

Patrick

  • Hi Patrick,

    Do you have any information on the digital filter settings? 

    What frequency of input clock is being used? 20MHz?

    Looking at the two datasheets, there may be an issue with the timing. Do you know if the code has been changed between tests? 

    The ADI part on the left specifies the timing to data ready from the rising MCLK edge whereas the AMC1204 on the right specifies the timing to data ready from the falling MCLK edge. Do you know when the sample is being recorded with regards to the MCLK?

  • Hi Alex,

      Thank you very much for the follow-up. Indeed it was the impact of bead in the input pins. After moving them, the accuracy is normal now.

      Appreciation to your feedbacks to help secure the part!

    Regards,

    Patrick