MUX reading problems

Thread Starter


Joined Dec 11, 2013

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



Joined Mar 14, 2008
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?