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ADS1298: Input impedance certification test issue

jun.tian
Prodigy 50 points

Part Number: ADS1298

Hello everyone,

      I have seen some people asking questions in the forum about the ADS1298 input impedance failing to pass the test standard(https://e2e.ti.com/support/data-converters/f/73/t/708969), but the problem does not seem to be solved. In the same test environment, the input impedance of other products (such as ADAS1000, AD8233) meets the standard requirements. As shown in the figure below, after adding a 0.62M resistor and a 4.7nF capacitor network to the input circuit, the detected waveform amplitude is attenuated by more than 10%, but the standard requirement is no more than 6%.
Can someone  help me ?

     

  • 0
    TI__Guru 68916 points

    Hello Jun,

    Thank you for your post!

    We have begun communicating with your local TI support team on this same topic.

    This question has been discussed at length in the past. Please review this thread below as many possible causes and tests were discussed. Embedded in my replies are some attachments that might be useful as a starting point: https://e2e.ti.com/support/data-converters/f/73/p/693255/2611200#2611200.

    To debug this further, we will need:

    • Test setup diagram
    • Test equipment description
    • A complete schematic
    • ADS1298 register settings
    • Input signal magnitude and frequency
    • Measured results

    Best regards,