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AMC1305M25: Figure 49. QuantizationNoiseShaping

Hirotaka Matsumoto
Guru 27595 points

Part Number: AMC1305M25

Hi all

Would you mind if we ask AMC1305M25?

On the Figure 49. QuantizationNoiseShaping, Magnitude is the worst at 800Hz.
Does AMC1305M25 have some trouble at 800Hz?
Our circuit board, our customer told us that there is shaking with 800Hz cycle.
If you have some advice, could you let us know?


Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Guru 56892 points
    Hello Matsumoto-san,

    Thank you for your question about the AMC1305M25.

    I believe that the 800Hz magnitude spike that you are describing in the Figure 49. FFT is actually the ~1kHz input signal tone on a logarithmic scale. There is no problem for the device at 800Hz.

    Do you have additional information in regards to your customers shaking issue?
  • 0 in reply to Alexander Smith
    Guru 27595 points

    Alexander san

    Thank you so much for your reply!
    Could you refer to the attachment file?
    20180319_AMC1305.pdf
    On our customer's circuit, they improved GND line.
    As the result, 800Hz shaking issue decreased almost.
    However, there are some shaking issues.
    That's why, we asked you whether AMC1305 causes for shaking issues or not.(just in case) 

    In case of PMW=10kHz cycle, there are no some shaking issues.
    So, in case of PMW=16kHz cycle, it occurs some shaking issues.
    We assume that this is caused by AMC1305's supply voltage.
    If you have some experience, could you let us know?

    Kind regards,

    Hirotaka Matsumoto 

  • 0 in reply to Hirotaka Matsumoto
    TI__Guru 56892 points
    Matsumoto-san,

    This looks like ripple. A better filter on the inputs of the device may fix the problem. Do you have a schematic for the portion of the board that has the AMC1305?
  • 0 in reply to Alexander Smith
    Guru 27595 points

    Alexander san

    Thank you for your reply!
    We will feedback you the customer's circuit after we get it.
    If it is possible, we would like to send it using private message on E2E.
    Could you accept "friend request"?

    Kind regards,

    Hirotaka Matsumoto