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RTOS/ADS1292: ADS1292

Hugo Wang
Expert 1525 points
Part Number: ADS1292


Tool/software: TI-RTOS

Hi sir

I have two question about ADS1292 as below.

1. If we use USB(D+/D-) connected with IN1P/IN1N, does DC voltage level cause issue at ADS1292?

2. As above, does AC signal cause issue at ADS1292?

Thanks for your great support.

  • 0
    TI__Guru 66816 points
    Hello Hugo,

    I'm not sure I understand your question. Are you using the ADS1292 to measure USB signals?

    Best Regards,
  • 0 in reply to Ryan Andrews
    Prodigy 160 points
    Thank you Hugo.



    Hi Ryan,

    Thanks for your reply, and let me explain it more clearly.

    In our design, we're using ADS1292 to measure ECG signals but it is possible D+/D- signal connected with IN1P/IN1N.

    In this case, we are afraid D+/D-(DC voltage/ AC signal) cause any effect at ADS1292.



    Thank you.

    BR

    Rex
  • 0 in reply to Rex Hsieh
    TI__Guru 66816 points

    Hi Rex,

    I would have two concerns with that:

    1. If the D+/D- signals are active and connected to the ADS1292 inputs at the same time, you must ensure the logic levels never exceed the supplies (AVDD or AVSS). The min/max input voltages for analog input pins is listed in the Absolute Maximum Ratings table. Exceeding these limits may cause permanent damage to the device.
    2. While measuring ECG, I imagine that you must find some way to isolate the signals. Noise or added leakage current could have significant negative impact on the ECG signal integrity. In general, we try to keep digital signals separated from the analog signal path as much as possible.

    Best Regards,

  • 0 in reply to Ryan Andrews
    Prodigy 160 points
    Hi Ryan,

    Thanks for your answers, it's helpful.

    We have another question, does Vcap refer to the analog ground or digital ground?


    BR
    Rex
  • 0 in reply to Rex Hsieh
    TI__Guru 66816 points
    Hi Rex,

    VCAP is referenced to AVSS, which would be ground for unipolar supplies. As Figure 31 demonstrates, this internal bandgap voltage is used to generate the internal voltage reference, which is also referenced to AVSS.

    Best Regards,
  • 0 in reply to Ryan Andrews
    Prodigy 160 points
    Hi Ryan,

    Thanks for your detail reply.

    BR
    Rex