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SN74LV4051A-Q1: Mux Output Issue

Part Number: SN74LV4051A-Q1

We have implemented the SN74LV4051 Mux for our data acquisition setup. During testing, it was observed that when the channel output configuration is changed, the mux gives an erroneous output and copies the data of channel 8 when channels 5,6, or 7 are required to be read. But, when the mux configuration is hard-coded for any channel, the mux output is correct. This error only occurs when the setup changes the mux output configuration while operation. Please help in understanding the issue, and provide some guidance on how to resolve it.

  • This sounds as if the voltage at the A/B/C inputs is not correct. Can you show oscilloscope traces of those and the I/Os?

  • Hello Abhishek,

    Can you expand more on what you mean by copying the data of channel 8 when 5,6, or 7 are to be read? Are you seeing the same output on 8 and the selected 5/6/7 or are you trying to read 5/6/7 and instead keep seeing 8?

    How are the input to the controls handled otherwise outside of the hard-coding? It does sound like the control inputs are incorrect, perhaps in some coding implementation you may be using.

    I'm seconding Clemens request here and if you could provide a scope of the control pins A,B,C with the I/O's it would be helpful to see what is happening here


  • Hi Rami and Clemens,

    So, to clarify what we are observing, we keep seeing 8 even when we tried to read channels 5/6/7. When we did a more in-depth analysis of the select cannel inputs, we found that the control inputs were incorrect, as the initialization of the select channels had some issues. Thanks for your swift responses!