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For my senior design project I'm using this ADC (HMCAD1511)

https://www.analog.com/media/en/technical-documentation/data-sheets/hmcad1511.pdf

I'm only using one of its four analog inputs - what should I do with the unused analog input pins?

Is it best to just ground them?

Lastly the same question but more generally for unused digital input and output pins, what should normally be done with them? (I'm guessing there isn't a catch all solution and that it often depends)

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  • \$\begingroup\$ wowsers that's a fast ADC! \$\endgroup\$
    – Marcus Müller
    Dec 10, 2018 at 0:14
  • \$\begingroup\$ No need to worry about termination of unused analog inputs as they are enabled or disabled by software, the register channel_num makes that selection, the three least significant bits of that register are used to select the funtion mode \$\endgroup\$
    – Eloy Calatrava
    Nov 1, 2020 at 19:37
  • \$\begingroup\$ you should ask an application engineer. \$\endgroup\$
    – Ben
    Mar 2, 2021 at 14:52

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Since the other three inputs will simply not be muxed to anything, you don't actually have to terminate them. For good measure: you want these to absorb any crosstalk, so short them with e.g. a 47Ω resistor.

This is a very high-speed ADC that you're using there.

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