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ADM3054 1MHz Emission fails

Dear Sir,

ADM3054 1MHz Emission fails

We are using ADM3054 for Can isolation transiver.

From Our EMC emission test , we can see every 1MHz noise (which over some limit line on 100MHz)

After some investigation , we have find ADM3054 make this noise.

- With Near field probe , ADM3054 make 1Mhz noise
- Check LISN and 5V line of ADM3054 VDD2, we find it as attaced.

I am not familiar with  the internal architecture of ADM3054.
Why AMD3054 make this noise?
From ADM3054 datasheets, It's seem there is no active switching components on ADM3054.

I hope your helps.

Best Regards,

  • From ADM3052 datasheets.

    I see 1MHz is refresh frequency of pulse.

    Is it same architecture?

  • Hello medmshk,

    The ADM3054 does have details of the refresh on page 16 of the datasheet:

    In the absence of logic transitions at the input for more than ~1 μs, a periodic set of refresh pulses, indicative of the correct input state, are sent to ensure dc correct-ness at the output.

    Even so, we haven't seen this causing emissions issues. Are there any other possible sources of the 1 MHz on the same board? Even a simple switching regulator or something? Or are there any long unshielded and untwisted cables, for example, supplying 5V directly from a power supply on the bench? Even with such a set-up, I wouldn't expect such high emissions, but even for something else on the board, it's something that unfiltered/unshielded power cables could contribute.

    Finally, is there adequate decoupling of the Vdd1/Vdd2 on ADM3054, and appropriate capacitors on the board's power supplies.

    Best regards,


  • Dear ConalW

    Thank you for your comments.

    I know what there is no detail about refresh pulse in ADM3054's datasheets.

    But ...

    - Connect 5V Vdd2 and check it LISN , we could see the figures as attached.

    - With Near filed probe and Spectrum Analyzer , We Could see this noise near ADM3054.

    Of course , the typical solution is add some capaciter to Vdd1 and vdd2.

    But from some regulation of our products , we could not add capaciter in vdd2.

    That's why , We have difficultly to reduce this noise.

    Thanks & Best Regards,

  • And



    There is description of refresh pulse and periods.

    So, we are thinking ADM3054 and ADM3053 using same architechture.

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