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ads1292r - current limiting resistors for patient protection

Vignesh Rao
Prodigy 250 points
Other Parts Discussed in Thread: ADS1292R

Hi,

I am using ADS1292R for ECG recording, I am making use of the demokit available for the same.

Please let me know where are the current limiting resistors used for patient protection(not circuit protection from defib pulse) in the inserted schematic image(provided in demokit manual pg-no 51/58)

Also let me know how to decide on value of those resistors.

  • 0
    TI__Guru 66256 points

    Hi Vignesh,

    The resistors that you are referring to on the ADS1292R EVM are R73, R85, R71, and R63.They are in series with the channel inputs and help to limit the current into the ADS1292R.

    For values, these tend to range around 30k-50k Ohms. On the EVM, they are installed as 51k.

    If you refer to the datasheet for the ADS1292R, Figure 49 shows these same components at values of 30k Ohms in accordance with the IEC 6061 specification.

     

    Low-Power, 2-Channel, 24-Bit Analog Front-End for Biopotential Measurements (Rev. B) (sbas502b.pdf) http://www.ti.com/litv/pdf/sbas502b

     

    While these components are called "Patient Protection Resistors," TI cannot legally comment nor guarantee anything related to patient safety.

     

    Regards, 

  • 0 in reply to Ryan Andrews
    Intellectual 280 points

    Hi Ryan Andrews,

    In our design, we are using 1 channel for ECG and other channel for Respiration. As per the evaluation board we used 51K resistor on R85, R73.

    1)  What is value of resistor we need to mount on  R71, R63  if i am going to use respiration on channel 1 ? because in evaluation board using 0E resistor on R71, R63.

    2) Suppose if i mount 51K resistor on R71,R63, will it affect respiration waveform?

    Thanks,

    Sivakumar

     

  • 0 in reply to siva kumar
    TI__Guru 66256 points

    Hello Sivakumar,

    R71 and R63 should be 0 ohms when Channel 1 is used for respiration measurements. C89, C90, C91 can be left as DNI. These components are included on the schematic to give customers the flexibility to configure the Channel 1 signal path the same as Channel 2 for 2-channel ECG.

    Best Regards,