Multiple capacitors in shunt vs. one for Filter

Discussion in 'The Projects Forum' started by sgonzalez90, Feb 5, 2014.

  1. sgonzalez90

    Thread Starter New Member

    Feb 5, 2014
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    Currently I'm modifying a circuit on voltage input of a controller.

    There are currently 2x 47uf caps, and a .1uf cap in shut (all rated at 50V) for transients...is there any benefit to having 3 caps as opposed to one of the same or greater value???

    I'm trying to minimize board space...only benefit I would think of would be the cost really...
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,526
    2,369
    The option of 2 caps, 1x100μf and 1x0.1μf will work.
    As long as the 47μf are presently located on an adjacent position on the board.
    Max.
     
  3. MrChips

    Moderator

    Oct 2, 2009
    12,440
    3,360
    Two 47μF caps are better than one 100μF because the ESR is lower in the smaller cap.
     
  4. sgonzalez90

    Thread Starter New Member

    Feb 5, 2014
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    Unless I find a cap with the equivalent or less ESR. I'm looking at Tantalum Polymers, Aluminum Polymers and Ceramics.
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,140
    1,789
    The large capacitors supply large amounts of current in response to a load transient. The small capacitor is for high frequency bypass. You might want to consider other space saving measures. You did not say if the components were thru hole radial or axial. You can also save space by switching to tantalum or SMT parts. All choices involve tradeoffs. It is well know that free lunches are getting harder and harder to come by.
     
  6. sgonzalez90

    Thread Starter New Member

    Feb 5, 2014
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    I'm using a radial surface mount, and I'm trying to avoid tantalum (Higher ESR). Tantalum polymer would be fine...
     
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