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ADS1299EEGFE-PDK: Inquiry ABOUT ADS1299's Detachment Detection

Katherine Wang
Intellectual 2210 points
Part Number: ADS1299EEGFE-PDK
Other Parts Discussed in Thread: ADS1299

Hi Team,

I use ADS1299 for EEG signal acquisition. ADS1299 is configured as single-ended sampling. Now the brain electrodes I use are active electrodes, which is to add a follower amplifier to the P end of a single channel. But after I use this design, the electrode's detachment detection function can’t be realized. I turn on the detachment detection, and it always shows that the connection is successful. Is this design really unable to realize the detachment detection function? (The mode used is DC-Lead off)

Kind regards,

Katherine

  • 0
    TI__Mastermind 19815 points

    Hi,

    May I ask which customer is this?

    If it cannot be disclosed in the public, please convert the thread to INTERNAL, or please let me know, so I can reach out to you via email.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Intellectual 2210 points

    Hi ChienChun,

    I've sent the information of the customer to you via email.

    Thanks and regards,

    Katherine

  • 0 in reply to Katherine Wang
    TI__Mastermind 19815 points

    Hi,

    Correct, the voltage follower output has low output impedance, which could affect the lead-off detection's current path.
    Yes, since op amp drives its output with low impedance regardless of whether the electrode is connected or not, the ADS1299 lead detection cannot work with an op amp inserted. They would need resistors at the op amp input (the electrodes).
    I think the ADS1299 lead detection works based on a differential lead bias to the channel inputs.
    So they might need to connect the 200M to ground on the op amp driving the N input and 200M to supply on the op amp driving the P input.

    Thanks