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TMUX6209: Noise Isolation Solutions for Digital Control Signals Passing Through Analog Areas - TMUX Series Multiplexers

haowei cheng
Prodigy 40 points

Part Number: TMUX6209

Hello,

I am designing a high-precision data acquisition system using TI multiplexers (such as the TMUX6209) to switch multiple analog sensor signals to a single-channel ADC.

The problem I am encountering:
The digital control signals for the multiplexer need to pass through the analog signal region on the PCB to reach the MUX. I am concerned that the edge noise of the digital signals could couple into the sensitive analog signal path and affect ADC sampling accuracy (target accuracy ≥16 bits).

Specific questions:
1. How does TI recommend handling the situation where MUX digital control lines pass through the analog area?
2. Is it necessary to add isolation components or RC filtering on the control lines?
3. Does the TMUX series have specific layout recommendations to minimize digital-to-analog crosstalk?
4. How much does the edge rate of control signals affect analog signal quality?

Thank you for your guidance!

  • 0
    TI__Mastermind 49515 points

    Hi,

    We have received your post and the investigation will take some time. Thank you for your patience.

  • 0 回复 Taylor
    TI__Mastermind 49515 points

    1. It is generally recommended to avoid routing noisy signal traces near analog traces. However, if control lines must cross an analog region, keep them as short as possible and route them over a solid ground plane.

    2. Typically no, The TMUX6209 logic pins are designed for normal digital control and have internal pull resistors. This device is intended for DAQ, so you can add a RC as a option only if you are having a real EMI or glitch problem.

    3. The TMUX6209, does have a layout section in the datasheet, ensure that there is good decoupling on VDD/VSS, a solid ground reference doing this can help with cross talk. But if possible route the digital pins away from the S and D pins. 

    4. A faster control edge can couple more easily into nearby analog nodes because of the high frequency energy so the edge rate does matter. You could use a RC filter like mentioned before to slow the rise time, and reduce the noise.