Inductor mag interference

Discussion in 'The Projects Forum' started by tindel, Feb 17, 2013.

  1. tindel

    Thread Starter Active Member

    Sep 16, 2012
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    A little help: I am laying out a Solar Array Cell Phone charger card. U1 can switch at up to 500kHz and U4 can switch at up to 400kHz. With this layout I'm concerned the mag fields on the inductors (L1 & L2) will interfere with each other even though they aren't on the same core. Is my intuition correct?

    Also, I'm not convinced I need C9, as that is the battery pack just to the right. I'm using LiMH. Thoughts?
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,649
    2,348
    Hello,

    Dependend on the type of inductors, there will be some coupling between them.
    You could try to shift L1 more toward C1 to create a larger distance.

    Bertus
     
  3. #12

    Expert

    Nov 30, 2010
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    I can't see how your inductors are wound but I can remind you that placing their magnetic fields at 90 degrees to each other will reduce the interaction by quite a lot.
     
  4. tindel

    Thread Starter Active Member

    Sep 16, 2012
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    Thanks guys - that's the kind of info I needed. I went with a little bit different layout to separate the inductors. The below link is the datasheet - it's hard to tell exactly how they are wound - I imagine they are wound around a magnetic core. I don't think orienting them at 90degress will help.

    http://www.murata-ps.com/data/magnetics/kmp_1300r.pdf
     
  5. #12

    Expert

    Nov 30, 2010
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    They are vertical core, horizontal wound, and if you mount one a bit too high and bend it over so its core is horizontal, the interaction will be very much reduced. It's a matter of physics. Whether you believe or not is irrelevant.
     
  6. tindel

    Thread Starter Active Member

    Sep 16, 2012
    568
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    Oh - I believe it and vaguely remember the EM class that proved it (right hand rule) - I just hadn't thought about leaving the leads long and bending one over. Good idea. Thanks.
     
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