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ADS1292R: High noise with Internal RLD routing

Haroad
Intellectual 1600 points
Part Number: ADS1292R

Hi, Ryan

    Our customer use ADS1292R for RESP and 1 lead ECG. They want to use internal RLD routing. But it will cause higher noise. Pls help advice how to optimize it.

    I'll send you details by email.

regards,

haroad

  • 0
    TI__Guru 66386 points
    Hi Haroad,

    When the RLD output is routed into the device through RLDIN, the signal can be connected to the PGA inputs (for RLD MEASURE) or to the channel input pins (for RLD_DRx) to drive the body with an alternate electrode. You CANNOT do both at the same time.

    For example, if you want to use Channel 2 to measure the RLD output, you would configure the Channel 2 MUX setting to CH2SET[3:0] = 0010. Then, RLDIN is connected to the positive PGA input and RLDREF is connected to the negative PGA input. At this time, the channel input pins (IN2P and IN2N) are disconnected from the MUX.

    In order to bias the electrode inputs without a dedicated RLD electrode, the customer could AC-couple the ECG inputs and connect a pull-up resistor from IN2P and IN2N to RLDOUT.

    Best Regards,
  • 0 in reply to Ryan Andrews
    TI__Guru 66386 points
    One additional note...

    If channel 1 is used for respiration, then the customer should only enable RLD2P and RLD2N to derive the RLD common-mode voltage.
  • 0 in reply to Ryan Andrews
    TI__Intellectual 1600 points

    Ryan,

       Thanks for advice.

       If we can't routing RLD signal to internal MUX as real right leg drive. As show in the .ppt file, can customer connect the RLD externally to IN2N, IN2P pins, as the right leg drive?

       Regards,

       Haroad