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AMC1305M05: Sinc3_16 and ripple wave relation ship

Part Number: AMC1305M05

Dear E2E:

  I Use AMC1305M05  as a sense currents  in green energy system. 
  In no load conditon:  sample rate: sinc3-16  the  ripple wave about channel 1 was a little high, but the channel 2 is normal;

But i change the sample rate: sinc3-32  the  ripple  wave reduce quickly  and the channel 2 still is normal;

  i have double check the GND & VDD net is fine, the schematic are the same. so i was little confused what's the reason?
  i also do load condition , the situation is same.  
             sinc3-16:  channel 1 is bad; channel 2 is fine;
             sinc3-32:  channel 1 is fine; channel 2 is fine;


  • Hello,

    Thanks for your post!

    When you say channel 1, do you mean MDAT06 and channel 2 is MDAT07?

    This could be a result of an offset in your nets (IA1, IB1, glA, glB) or perhaps channel 1 is closer to a noise source that is susceptible at sinc3-16 sampling rate.

    Can you provide additional schematics showing these nets as well as the channels location on the board?
  • Dear Alexander:

    Schematic 1:

    Load circuit:

    ISO Power:

    Circuit Measurement :


    And i have double check the PCB layout about A-Channel and B-channel. the different is  the position of resistor R1 & R2,
    and so the via  in A-channel near C31/C41.  

    A channel:

    B channel:

  • Hello,

    Thank you very much for the detailed schematics and layout.

    I think this is noise coming from R1 and going directly to the device. I would suggest moving R1 above C41 and C31 such that the trace must pass through the capacitors before going to the device.

    On channel 2, the resistor R2 connects to the capacitors (C42, C32) before going to the device.
    On channel 1, the resistor connects directly to the device in one direction, and the capacitors in the other.