MUX reading problems

Discussion in 'Automotive Electronics' started by binukannur08, Nov 20, 2015.

  1. binukannur08

    Thread Starter New Member

    Dec 11, 2013
    2
    0
    Hai,

    Iam using 8 channel analog MUX SN74HC4851, in a temperature reading application.

    Here there are 24 NTC thermister to read with one MCU analog pin , using 3 MUX.

    In my circuit all channel selection pins and common output pin s are connected parallel, and MUX selection is done by ENABLE pin separately, and read all MUX sequently.

    My problem is , suppose channel 1 of MUX 1 is HIGH, and all other channels LOW practically..but corresponding pin of MUX 2 also shows high. Not may be the exact value.I use proper delay and all other precautions, but no use. Individual MUX gives good values in all channels

    Please give me the error possibilities.

    Below schimatic is given,

    Here , output signal conditioning , MCU and thermister circutary are omitted
     
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  2. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    I'm sorry but your description of the problem is not clear. :confused:
    Can you restate the problem using different wording?
    How is it not working?
     
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