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  • Combo inductors

    All comercial power supplies I know used some kind of torroid core that has 4 different inductor on it. It allows a great physical space saving. I have opened about 6 different power supply from different manufacturers, they all use it.
    The values of the inductors are quite similar to the one needed for sproggy. If I use one of those "combo-iunductor" I would gain about 3 square inches of space, thus reducing the size of sproggy down.
    Are you guys aware of any limitations / problems / watch outs for such design?


    Thanks

    abbas

  • #2
    "Combo-inductors" are more commonly known as transformers. The sproggy design is constructed from separate regulator circuits. The transformer design you see most manufacturers using is similar to the +12/-12 section of the sproggy.

    It is non trivial to combine all of the inductors of the sproggy into a single transformer, since the regulators will all have different switching frequencies and will interfere with each other.



    Rob
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.

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    • #3
      Originally posted by Rob Withey
      "Combo-inductors" are more commonly known as transformers. The sproggy design is constructed from separate regulator circuits. The transformer design you see most manufacturers using is similar to the +12/-12 section of the sproggy.

      It is non trivial to combine all of the inductors of the sproggy into a single transformer, since the regulators will all have different switching frequencies and will interfere with each other.



      Rob

      Thanks for the answer. I am very sure it is not a transformer. Take a normal choke and add another layer of wire that give you 2 chokes on one torroid.

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      • #4
        I believe they are inductors, as transformers have a primary and secondary side, but in these, each winding connects the two sides instead of returning to the same side.

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        • #5
          this is what I am talking about. Any Ideas?

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          • #6
            I do think they are a common choke or inductor, the difference however between the sproggy and the computer power supply is that with the computer ps, all the outputs are driven by a single PWM chip and all operate at the same frequency, but with the sproggy, they are controlled by multiple chips which operate at different frequencies, as Rob said.

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            • #7
              Thanks for the info!
              I was hopping to use /reuse them but I guess if the frequense is different between the maxim chips used in sproggy it may be a problem.

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