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ADS1292R: Debugging issues

Chu Allen
Intellectual 390 points
Part Number: ADS1292R

Tool/software:

Dears,

I have two questions to ask: We are currently using ADS1292R to collect electrocardiogram (ECG) and respiration.

When using a simulator to collect data, there are no ECG waveform features on the respiratory waveform.

However, when using a human body to collect data, there are ECG waveform features on the respiratory waveform. Is this normal?

Another issue is that the amplitude of the respiratory waveform collected from the human body is very low.

We want to know if we can improve the amplitude of the collected respiratory waveform by modifying the hardware circuit.

Below is the current circuit

  • 0
    TI__Guru 63196 points

    Hello Chu,

    Thank you for your post. 

    The circuit shown in your schematic image looks correct. You can try the following modifications:

    1. Decrease C20 and C29 to 470pF. This will move the high-pass filter cutoff to > 60 Hz, which will help to reject power line interference.
    2. If needed, you can try to increase the RESP modulation current by decreasing R18 and R24. The modulation current is determined by the reference voltage (VREF) and the total impedance between RESP_MODP/N. Assuming a baseline body impedance of  2kΩ, the modulation current would be 2.4V / [2*40.2k + 2k] = ~29µA. Note: this will increase the baseline voltage and the peak-to-peak swing seen at the IN1P and IN1N pins, so the current cannot be scaled so large as to violate the absolute or differential input voltage limits.

    Regards,

    Ryan

  • 0 in reply to Ryan Andrews
    Intellectual 390 points

    Dear Ryan,

    Thanks. I will check it.