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ADS1230: Leave inputs floating

Elmar D
Prodigy 20 points
Part Number: ADS1230

Is it allowed to leave the AINP and AINN inputs of the ADS1230 floating? Or must they be pulled down/up using resistors?

In our application we are using multiple ADS1230 converters, and it is possible that a user leaves one of the channels unconnected. Do the internal ESD diodes limit float voltage, or must external protection be added?

  • 0
    TI__Guru** 112765 points

    Hi Elmar,

    You have two very different questions.  In the first question you ask if the inputs can be left floating, and they can.  Analog inputs differ from digital in that they can operate throughout the input range which is usually the analog supply.  This differs from digital inputs where excessive current can be drawn in a float state where both PMOS and NMOS can be conducting. 

    The second question has less to do with floating inputs of the ADC itself and more to do with general input protection.  If ESD or EMI/RFI affect the input whether connected or not, the Absolute Maximum Ratings for the ADS1230 must not be exceeded.  Often times input filter resistance will limit current sufficiently to 10mA or less.  With ESD transients, the voltage can be quite high and may require TVS diodes as external protection in front of the input filters to limit the input voltage from kVs to less than 24V depending on the clamp voltage of the diode.

    Best regards,

    Bob B