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ADS1298: RLD lead off indication

Shanoj G
Prodigy 150 points

Part Number: ADS1298

Hi,

We are using ADS1298 chip in our ECG project. From the datasheet, i understand this offers lead off detection for 9 leads in 10 lead (physical) ECG system. The RLD (N) lead removal is not able to detect with ADS1298 due to obvious reasons. May i know whether you have any solution already figured out for RLD lead off detection? I see there are products in market with this feature.

thanks

Shanoj

  • 0
    TI__Guru 69446 points

    Hello Shanoj,

    Thank you for your post.

    The ADS129x forces the current on INxP and INxN of a given channel to be of opposite direction. In the event that the RLD electrode becomes disconnected, it's possible for these lead-off current sources to keep the body biased near mid-supply and RLD lead-off will go unnoticed.

    One possible solution is to use lead-off current in the same direction on all electrode inputs. This would require external pull-up or pull-down resistors. If all electrodes monitor for lead-off with the same current direction, an RLD lead-off event will cause all inputs to be pulled-up/down simultaneously.

    Best regards,