Capacitor breakdown voltage

Discussion in 'General Electronics Chat' started by mahela007, Sep 3, 2011.

  1. mahela007

    Thread Starter Active Member

    Jul 25, 2008
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    In practical applications, will there be any difference in performance between two capacitors which have identical characteristics except for their breakdown voltage? More specifically, will there be a difference in performance in a series LC (inductor capacitor) circuit?

    Of course, it must be assumed that both capacitors operate at voltages lower than their respective breakdown voltages.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    There may be a difference in the leakage rate, depending on the size of the cap and the difference in voltage rating.

    Electrolytic capacitors' acceptable leakage rate is based on both their uF and voltage rating. As voltage rating increases, acceptable leakage rate increases. As uF rating increases, acceptable leakage rate increases.

    Also, the higher the voltage rating, the greater the thickness of dielectric between the plates is required. Since the dielectric thickness increases, the plate area must be increased to compensate. Since the plate area increases, the parasitic inductance and resistance will also increase.

    While these parasitics will have a relatively small consequence at low frequencies, they really come into play at higher frequencies. The larger the cap size/voltage rating, the greater the parasitics.

    A size 0805 100pF 50v multilayer ceramic cap might measure that at DC frequencies (< 20MHz), but at 500MHz, the effective capacitance can triple due to the parasitics.
     
  3. mahela007

    Thread Starter Active Member

    Jul 25, 2008
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    I understand how capacitors work but I didn't understand that statement.. could you explain what the plate area must increase?
     
  4. SgtWookie

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    Jul 17, 2007
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  5. mahela007

    Thread Starter Active Member

    Jul 25, 2008
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    ah ok.. I get it now. Thanks.
    C= A\epsilon / d

    as D increases, A must increase to keep capacitance constant.
     
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