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ADS1298 ac lead off detection

Gang Zhou
Prodigy 20 points

Other Parts Discussed in Thread: ADS1298

Hi,

I'm using ads1298 for EEG signals acq. ,and additional preamp added ahead of the ads1298. I'd like to know how to do ac lead off detection in this case? Is it a right way to establish the connections between the input (electrodes)of the preamp and INP/INN of the ads1298?

Best regards,

Gang Zhou

Hotgen Biomedical

  • 0
    TI__Expert 3260 points

    Hello Gang Zhou,

    The ADS129x Lead Off function will not work if there is an amplifier on the input. This is because the AC Lead Off signal will not get passed the amp and out to the electrode. The only option is to externally create the signal.

    Depending on the noise performance target the ADS1298 may be used without an external amp. System noise of <3uVp-p is achievable with 65Hz BW (derived from the noise tables HERE in the ADS1298 datasheet, beginning on page 9).

    Regards,

    Michael

  • 0 in reply to Michael W
    Prodigy 20 points

    Hello Michael,

    Thank you  for your help.

    One thing is still unclear: We usually use bandpass filters in first stage of signal acq.(e.g. 0.5-150Hz for ECG). However, these filters wil block the ac or dc lead off signals  producted by ADS129x  out to the electrodes. Dose lead off detection work in this case?

    Best regards,

    Gang Zhou

     

  • 0 in reply to Gang Zhou
    TI__Guru**** 183361 points

    Hi Gary,

    If you are using passive filtering, you should be able to use the lead off detection of the ADS1298.