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ADS1298R Lead Off and Right Leg Drive

JasonHaedt
Genius 3320 points
  1. Lead Off  (DC Lead Off is used)
    1. I am having issues with lead off.  It could be the proper selection of sensitivity.  I am running a RIGHT LEG REFERENCE, ie., right leg connected to system ground.  I am recognizing Lead Off on every lead except RL.  Thoughts?  RL referenced to ground is a typical implimentation.
  2. Right Leg Drive
    1. Is driving RL a better solution for Lead Off on RL?  Thoughts?

      Thanks, Jason 

  • 0
    TI__Mastermind 18285 points
    Jason,

    I am moving your post to the correct forum.
  • 0
    TI__Mastermind 38745 points
    Hey Jason,

    Great question! The lead-off detection mechanism is a voltage comparator near the input where a current source is injecting a known current out onto the pin. Tying the pin to a specific voltage will inherently prevent the voltage comparator from ever triggering a detection.

    In addition, using DC lead-off detection while the RLD amplifier is powered on will also prevent detection since the current from the lead-off current source will simply drain into the amplifier. It turns out that detecting whether the patient drive electrode is connected in real time is rather difficult. If it is absolutely critical for your application, there are some rather complicated strategies that may be implemented involving detecting lead-off on all the other electrodes which would indicate that the patient drive is disconnected.

    Regards,
    Brian Pisani