Voltage divider for input to two A/D converters

Discussion in 'The Projects Forum' started by garch, Dec 17, 2008.

  1. garch

    Thread Starter Member

    Aug 23, 2008
    24
    0
    Hi,

    I have an analogue dc signal of 0 to 5V. I have two 8 bit A/D converters. I would like to split the 0-5V signal into two 0-2.5V signals so that I can use two 8 bit A/D converters (rather than just one) to improve the resolution of the measurement between 0 and 5VDC ie 256bit resolution (A/D #1) for 0-2.5V, then 256bit resolution (A/D #2) for the 2.5v-5v range.

    Can I do this with a resistor voltage bridge?

    Thanks
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    Nope. But you could do it with some simple op amp circuits.
     
  3. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    I have always wanted to try the following circuit but I have never tried it.

    Perhaps you can tell me if it works or not by building it. The TL431 is an accurate 2.5V regulator working as a zener here.
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    [​IMG]

    This would work, but you really need to be able to tweak the voltage a little, as it is unlikely that both components would be right on value.
     
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