How to clip transient voltages outside 0~5V range

Discussion in 'General Electronics Chat' started by tpny, May 19, 2012.

  1. tpny

    Thread Starter Member

    May 6, 2012
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    I need to make sure signal going into my adc is within 0~5V. How do I clip voltages outside this range? Thanks!
     
  2. #12

    Expert

    Nov 30, 2010
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    6,817
    The usual way is to place 2 diodes on the signal line with one placed to allow excessive positive voltage excursions to be dumped into the positive (5v) power line and one that allows voltage excursions below zero to be dumped into the common (0 volt) line. A resistor is placed in series before the diodes to limit current through both of them. Shottky diodes have the lowest forward voltage when dumping transients.

    Then again, most devices that are sensitive to this have these diodes inside them and you have only to place a series resistor to limit the current that needs to be dumped.
     
  3. tpny

    Thread Starter Member

    May 6, 2012
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    Is it possible to clip it exactly at 5 volts and 0 volts?
     
  4. #12

    Expert

    Nov 30, 2010
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    I believe it is, but nobody has included these circuits on integrated chips that would only need a few more transistors in addition to the thousands they already contain, so I think it isn't all that important.
     
  5. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
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    A clipper based on an op amp can do this. Use google.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    3,236
    It's possible, but it would add significant complexity, and there's no reason to do that for your requirements.
     
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