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Planar cores

Discussion in 'Electronic Design' started by Yzordderrex, Aug 16, 2007.

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  1. Yzordderrex

    Yzordderrex Guest

    I need to get some gapped planar cores for chokes. I need a source
    and I would also like to see some Hanna curves on cores (or equivalent
    info) to help me pick out the right parts. Does anybody know of a
    good source of parts and literature.

    I'll be buying tens of thousands - so this isn't a give me some
    samples for a home brew project and never see me again.

  2. Eeyore

    Eeyore Guest

    The only planar cores I know are the E-PLT types.

    Check out IEC62317-9 btw

    You are supposed to provide the gap yourself usually by machining or using
    shims (or loaded glues).

    For calculation of characteristics with the gap I suggest you use Epcos's
    Ferrite Magnetic Designer tool available free from their website.

  3. Paul Mathews

    Paul Mathews Guest

    Magnetics distributors like Allstar and Eastern Components (in USA)
    will do secondary operations and provide you with anything you want.
    One approach for planar cores is to have E-cores machined down....most
    of the legs required dimensions. Gapped cores can be
    cheaper than ungapped, because their faces don't need a fine finish.
    Asian ferrite suppliers will also accomodate, provided your volume is
    sufficient. Custom tooling for ferrites is quite inexpensive, since
    ferrites are compression molded. As far as models of cores are
    concerned, you can usually get away with using the same models for cut-
    down cores as you would for the complete core, since the gap(s)
    dominate their characteristics. Of course, you'll need to make some
    corrections for losses and their thermal consequences, since losses
    are proportional to volume.
    Paul Mathews
  4. Terry Given

    Terry Given Guest

    Hi Bob,

    in the Philips Ferroxcube MA01 databook 2000, p. 39 Fig. 25, they have
    I^2L-vs-gap curves (IOW your Hanna curves. havent heard that name for a
    while now...)

    I have it on PDF, its 6.3Mb, email me terry underscore given at ieee dot
    org and I will send it to you (or just that page if you like).

    PhillipsFerroxcube (or whatever they are now called), along with Epcos
    (again, or whatever...) do a range of pre-gapped planar cores. they dont
    do gapped PLT cores though ;)

    your qtys are high enough its worth buying pre-gapped cores. My personal
    preference (for E-E assemblies) is to use a pair of identically gapped
    cores, that way you cant screw up the assembly. It is, however, slightly
    cheaper to use one ungapped core and one gapped core, but of the four
    possible combinations, only one is right....

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