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DC-DC isolating converter

Discussion in 'Electronic Design' started by Michael, Nov 12, 2008.

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  1. Michael

    Michael Guest

    I need to separate noisy part of the circuitry from the sensitive one.
    Does anybody make isolated DC-DC converters with reasonably low
    interwinding capacitance (or shield windings) or I am on my own?
    To make it even more painful: primary voltage is 7-8V (not common).
    ~10W power.
    I am looking at the moment - nothing has popped up.
    Thank you!
  2. Guest

    How 'bout an opto-isolator? Transformers just don't work at DC.

    George Herold
  3. cassiope

    cassiope Guest

    In my work (biomedical research instruments) I've had to design my
    including custom-made transformers. This is tough when your
    are really low.

    If you find anything (particularly with low capacitances and low
    currents) I'd sure be interested.

  4. whit3rd

    whit3rd Guest

    Err.... it might not be practical, but in high voltage installations,
    not uncommon to have a motor/insulated coupling-belt-shaft/generator
    to get a really well isolated power supply. 10 MV isolated power
    is almost always done this way.

    "Interwinding capacitance" can be reduced by using C-cores and
    keeping the windings for the primary and secondary distant one
    from another, of course, or by putting a foil shield into the recipe
    for winding.
  5. neon


    Oct 21, 2006
    fIRST FIND OUT WHERE THE NOISE SOURCE IS.i If it is on the ground daisy chain or RF then iI can help you.
  6. Michael

    Michael Guest

    Thanks to everybody!
    I have two more issues:
    1. Projected volume is 1-5k/year (off-the-shelf solution is very
    2. It is hand-held instrument (it will be difficult to "sell" motor-
    generator isolator to our mechanical guys)
    I am still looking. Most of the converters I've found so far have
    hundreds pF in-out capacitance. I need something in the order of
    single pFs
  7. GregS

    GregS Guest

    No voltage was specified. Look for "medical supplies", some
    have less than 15 pf.

  8. Guest

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