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Ads1298 Power Down Channel Noise

Oscar Baumann
Intellectual 835 points
Other Parts Discussed in Thread: ADS1298

Hi Tony,

I have one question when all the channels of the ADS1298 are powered down, sometimes appear a little signal in some channels i want to know if that signal probably is noise or could be another problem.

  • 0
    TI__Mastermind 43915 points

    Hi Oscar,

    You may be seeing the small input bias current from the PGA in combination with any input impedance. Powered down channels will still draw very small input bias current. We recommend tying any unused channels to the AVDD power supply to avoid having issues.

    Regards,

    Tony Calabria

  • 0 in reply to Tony Calabria
    Intellectual 835 points

    Hi Tony, thank you for your response.

    I have some glitches in the signal, in the following figure you will see the problem.

    I really apreciate your help.

  • 0 in reply to Oscar Baumann
    TI__Mastermind 43915 points

    Hi Oscar,

    Is the data that you are you reading back from the channels that are powered down or on the adjacent channels which are powered up?

    The powered down channels should be reading back as all zeroes. The adjacent channels should not be affected by anything that is powered down. Glitches should not happen unless there is noise in the system (possibly on the SPI interface lines) or an invalid read back of data. Have you looked at your SPI interface to make sure that there are no glitching that is occurring.

    Regards,

    Tony Calabria