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ADS1294: We would like to know the difinition of Comparator Threshold for the Lead-Off Detection

Shinichi Amano
Prodigy 10 points
Part Number: ADS1294
Other Parts Discussed in Thread: ADS1298

Hi,

We need some help regarding the lead off detection function.

We are using the DC Lead off detection mode with 95% - 5% as a COMP_TH. 

More than frequently,  our device with ADS1294 triggers the lead off function even when the electrode(s) are intact and connected to the human body. 

We would like to troubleshoot it but, first of all, we have no idea the COMP_TH.....95% relative to what voltage ??

Thanks,

Shin

  • 0
    TI__Mastermind 19815 points

    Hi Amano-san,

    The percentage could be relative to the AVDD and AVSS you are supplying.

    E.g. if AVDD is 3V and 95% is selected, then it would be 3V * 0.95 = 2.85V.

    To help troubleshooting, 

    Have you tried this Lead-Off detection method using the ADS1298 evaluation kit/board(EVM) with an ECG simulator?

    Also, do you use the RLD drive/electrode?

    In addition to the the current magnitude and frequency settings and RLD, electrodes/patches materials, gels, skin conditions, wires/cables are also very important that could affect the Lead-off detection stability.

    It's suggested to try/test the registers settings using ADS1298 evaluation kit/board(EVM) with an ECG simulator first for find the working combinations.

    Thanks

  • 0 in reply to ChienChun Yang
    Prodigy 10 points

    Will do !　Thanks ! We might have another question after tweaking the setting and check the signal. 

  • 0 in reply to Shinichi Amano
    TI__Mastermind 19815 points

    No problem.

    Again, It's suggested to do enough tests&validations and note down the settings on EVM first.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 19815 points

    Hi,
    Since I did not hear back from you, I believe my suggestions answered your questions.
    I will close this post and if you have any pending questions, feel free to post them here or open a new thread.
    Thanks and have a great day!