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TMUX1134: Crosstalk inquiry

Renan Santos Adriano
Mastermind 19975 points
Part Number: TMUX1134

Hello Team,

My customer has a microcontroller with 8 ADC pins which he trying to multiplex using the 4x 1:2 SPDT TMUX1134 chip so that their design can accommodate 16 input channels.

Using TMUX1134 chips, and for all 8 SEL pins, They are using a single GPIO output from the microcontroller to alternate the switch states between High and Low.

Unfortunately, they seeing crosstalk between my two signals. Can you share details/way how to fix it?

Regards,


Renan

  • 0
    TI__Mastermind 47907 points

    Hi Renan,

    I just want to get a little bit more information so I can better understand the problem:

    1) What Voltage supply is the TMUX1134 running at ,what are the signal levels at the input of the 1134, and what is are signals bandwidth approximately at?

    2) Are they seeing voltage transients during switching on the output lines?

    3) I am a little bit confused on where the cross talk is occurring. We typically define cross talk as interference between two I/O pathways - i.e. channel X signal is coupling into channel Y's signal. I just want to verify that this is what is occurring because I am not sure if it is that or a charge injection issue. 

    4.) If possible scope shots of the issue would be very helpful to help diagnose what exactly the problem is. If it is cross talk and the error is out of spec for what the 1134 is rated for it typically is a layout issue - but if its a charge injection issue that could fixed by adding a bit more output capacitance.

    Please let me know so I can start digging into this problem a bit deeper for you!

    Best,

    Parker Dodson