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ADS1299-6: For a referential montage, do I need to connect the negative inputs or can I just ground them?

Rishan Patel
Prodigy 50 points

Part Number: ADS1299-6

Hi guys, 

Quick question. I am using the ADS1299-6 in daisy chain mode with 3 devices. I am looking for a referential montage, so far I have left the negative inputs floating but somebody pointed out that the data sheet says (on the bottom of page 6, bullet point 2) that I should tie to AVDD. I didn't quite get why, I have my SRB1 wired as the app notes suggest so just thought i'd ask for clarity! 

<- I have left them floating

Thanks in advance guys! 

  • 0
    TI__Mastermind 19815 points

    Hi,

    Do you happen to have/use an EVM?  Have you tried using an EVM to test&see whether to measure/collect the EEG signals using or not using the Reference Electrode in a referential montage setup? 

    -------------------------------------------------------------------------------------------------------------

    It really depends on customer's product designs and applications, and it leave for customers to make decision based on the experiments, tests, data collection and analysis.

    -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    For the note/comment on page 6 "(2) Connect unused analog inputs directly to AVDD.",   this is for the case if one doesn't use such channel at all, i.e. not using both inverting and non-inverting input terminals.

    In other word, if either inverting or non-inverting input terminal of a channel is used to acquire signal, you don't need to connect the unused pin of that channel to AVDD. It will become user's decision how to treat the unused pin of a channel that is in-use based on the applications, tests, data collection&analysis.

    Thanks