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ADS8343 - Unused Input Channels, Leave Floating or Ground Them?

Other Parts Discussed in Thread: ADS8343

Hello,

I'm trying to decide which configuration of the ADS8343 will result in less noise on the device. On my layout, I currently am only using one of the input CHX channels (CH0), while the others are left floating. CH1 runs to a 16-channel mux and so the CH1, CH2, and CH3 channels are not used or needed. I will keep the ADC in the single-ended channel select state for CH0 only. In this configuration is it better from a noise perspective to ground the unused CHX inputs via wiring changes on the PCB or should I leave them floating? 


  • What is your input signal (for ADCs)
    • One used ADC channel (CH0) which connects to the output of a 16-channel mux. Switches between housekeeping channels (voltage monitors, etc.) which range of 0-5V. CH1, CH2, and CH3 unused and floating in the current layout. 

  • Reference voltage
    • +2.5V
  • Input and reference drive circuits
    • Info available if needed
  • Register settings used (if applicable)
    • Info available if needed
  • Digital control pin settings (i.e. Reset, Power Down, Start, etc.)
    • Info available if needed
  • Supply voltages
    • +5V
  • Schematics & layouts (attached within the post in case your design is not confidential or submitted by direct email topa_deltasigma_apps@ti.com with reference to post)
    • Info available if needed

  • Hello Stephen,

    In the case of channels that are not used in the application, the recommendation is to connect the unused channels to the GND plane via a pull-down resistor. Please feel free to post your schematic/board layout information if you would like us to review the design. 

    Thank you and Best Regards,

    Luis