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DP83825I: EMC compliance

Part Number: DP83825I
Other Parts Discussed in Thread: TLK100, TIDA-010046

Tool/software:

Dear TI,

We are in the process of designing a product which uses DP83825I. The product is an iteration of an earlier product which used TLK100.

When we performed EMC testing on the TLK100 based product, our design was initially very marginal against class B radiated emissions limits in the typical 100M ethernet frequency range 50-100MHz. TI were able to provide some register settings for this device which helped to reduce the emissions by a few dB giving us a pass with more margin.

We are soon going to test the DP83825I in a EMC test facility. In our own-lab tests we see the emissions from DP83825I being slightly higher than the TLK100 design.

Time in an EMC test house is expensive, and they are often booked up many months in advance. We like to be prepared by having strategies in place to reduce emissions for key components if we suffer fails or marginal passes.

As such, my question, is whether there are register settings for DP83825I (similar to TLK100) which can be used to reduce radiated emissions of 100M.

Thank you,

Ben

  • Hi Ben,

    It is unexpected that DP83825 will have headaches regarding emissions testing. You may consult TIDA-010046 where the board is below Class B and mimic appropriate board design practices as the authors of the app note.

    We also have an appnote (SNLA466) which can assist with debugging EMC-related issues.

    In general, if EMC requirements are strict for a system, we would recommend using DP83822 opposed to DP83825.

    Sincerely,

    Gerome

  • Thanks Gerome,

    The design is following the guidelines in general. Our customers require unshielded cables in our application, and we therefore perform EMC test using unshielded cables. All TIs tests seem to be done with shielded cables. 

  • Hi Ben,

    Thanks for the information. Having unshielded cables especially with EMC testing is a unique use case. Can you provide more information about this constraint and which standard are they testing against? I can relay to my inner team for future consideration on parts. 

    To answer your original question, DP83825 has registers to tune the MDI. Please see SNLA266 section 4 for more information.

    Sincerely,

    Gerome

  • Hi Gerome, thanks for the link, I will work through that. I have replied in answer to your other question via our FAE.

    Best regards,

    Ben