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ADS1292R : how to provide patient protection

Mahendra Patel1
Expert 3560 points

Hello All,

Please suggest us how to provide patient protection in configuration attached.

In the configuration we are providing protection to patient through R1, R2 as well as series capacitors for dc current for respiration channel only.  

But in above circuit we are not providing protection to patient from ECG channel(IN2P and IN2N). We are using only 2 electrodes for ECG and same electrodes for respiration.

We have referred sbaa181.pdf for providing patient protection for respiration channel.

Thanks & Regards,

Mahendra Patel

  • 0
    Guru 14640 points

    Mahendra:

    One document you should take a look at is the ADS1x9xECG-FE Demonstration Kit User's Guide (SLAU384) - it has a detailed schematic for connecting the ADS to the "DB9" connector and may give some further insight into tehe circuitry that TI used for the demo kit.

     

  • 0 in reply to Todd Anderson78572
    TI__Expert 3560 points

    Hi Todd,

    Defibrillator protection and patient protection circuitry are not provided on the ADS1x9xECG-FE board, as it is mentioned on page 27 of the document.

    Can you please guide here?

    Regards,

    Mahendra Patel

  • 0 in reply to Mahendra Patel1
    Guru 14640 points

    Mahendra:

    Sorry, I do not have experience with those items - maybe someone from the TI Precision Data Converters group can help!

     

  • 0 in reply to Todd Anderson78572
    TI__Guru 66186 points

    Hello Mahendra, 

    The Channel 2 ECG path is simplified in Figure 56. Normally, input low-pass filters would still be included for anti-aliasing on the ECG channels, while the Respiration channel would look as shown in the figure. The series resistance from these low-pass filters would provide some protection from DC current to the body. As Todd mentioned, you can find an example how the two input signal paths are different in our EVM User Guide.

    Additional patient protection may still be required for the electrode inputs, such as TVS diodes. This protection would only be required for each electrode input, not necessarily each device input. So in this configuration, RA and LA are shared by Channel 1 and Channel 2, but diodes would probably only be needed to the left of the diagram in Figure 56 (where you see "Left Arm Lead" and "Right Arm Lead").

    Apart from these suggestions, our team cannot comment on specific patient protection designs. It is up to the customer to ensure that their design meets IEC specifications.

    Best Regards,

  • 0 in reply to Ryan Andrews
    Prodigy 185 points
    Hi Mr. Anderson,

    Thanks for your reply and providing details about patient protection. We appreciate that..

    I also want to verify, if the capacitors used in AFE section need to be any particular specification like COG / NPO or else. The questions is more from accuracy perspective and we understand that COG is better with respect to X7R in terms of temperature coefficient. We intend to go with X7R, since capacitors values are easily available in smaller packages and we want to have our design as small as possible; since it's a wearable product. Please suggest.

    Thanks & regards,
    Vishal