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福邹000's avatar
福邹000
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6 years ago

How to avoid EMI problem when we use EN5339QI to transfer 5V to 3.3V.

Hi all,

We are using EN5339QI and EN5319QI in many of our projects.The current of EN5319QI is about 200mA,and the current of EN5339QI is about 3A.When we did EMI test,we found that the radiation at 150-180MHz is very strong near EN5339QI, but the radiation near EN5339QI is slighter.

Our PCB Layout was following the Recommendation 1 of the datasheet.Please help to put forward some suggestions on EMI.

Thanks a lot!

2 Replies

  • Mostafa_Intel_AE's avatar
    Mostafa_Intel_AE
    Icon for Occasional Contributor rankOccasional Contributor
    6 years ago

    Hello,

    Please correct me if i am wrong, you mean the radiation near EN5339 is higher than EN5319, if so that make sense where EN5339 has higher current and lower internal inductor.

    You will need to add a bead in the input side between the input capacitors and the input voltage supply to reduce the current noise on the input line.

    Regards,

    Mostafa

    • 福邹000's avatar
      福邹000
      Icon for New Contributor rankNew Contributor
      6 years ago
      Dear MOSTAFA, Thank you for answering my question. Your answer let me know how to design next, I will add a bead in the input side and do some experiments. Many thanks for your help.