Dual polarity for regulator input

Discussion in 'General Electronics Chat' started by mcgyvr, Apr 12, 2012.

  1. mcgyvr

    Thread Starter AAC Fanatic!

    Oct 15, 2009
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    Looking to use something like a LT3988 switching regulator or a LT3990 to get generate a 12V supply (50mA max load) for a project I'm working on.
    Input voltage would be +24 to +48VDC
    But my question is that I would also like it to also accept -48VDC as the input voltage.
    Would just a diode bridge before the input to the LT part work? Or what are the better/recommended ways to accomplish this..

    and in no way am I tied to those LT parts just the first few I came across..
     
  2. k7elp60

    Senior Member

    Nov 4, 2008
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    Sure a diode bridge is a good way to steer the right polarity of the input to + and - of regulator.
     
  3. crutschow

    Expert

    Mar 14, 2008
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    The bridge will work only if the input voltages are floating with respect to the regulator's ground.
     
  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    It seems to me that the only purpose of using a bridge would be if the input polarity is unknown.
     
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