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ADS7138-Q1: Regarding unused port

? ??
Prodigy 160 points
Part Number: ADS7138-Q1

Tool/software:

Hello experts,

ADS7138-Q1 has 8 channels.

We will use 5 or 6 channels in it.

Is it possible to connect a pull down resistor (about 100k ohm) to unused ports to avoid unpredictable behavior?

Best Regards,

Toru Kimura.

  • 0
    TI__Expert 6790 points

    Hi Kimura-san,

    It is best that unused channels be grounded directly with a trace to avoid any noise from being introduced to the analog inputs by leaving them floating. Is there a particular justification to use such a high value, weak pull-down resistor? I would think if a pulldown were to be used, it would be a lower value, strong pull-down resistor. 

    Regards,
    Joel

  • 0 in reply to Joel Meraz
    Prodigy 160 points

    Hi Joel-san,

    Thank you for your answer.

    >Is there a particular justification to use such a high value, weak pull-down resistor?

    There is no reason to use high value resistor.

    We want to connect to GND if is it possible.

    Is it possible to connect GND?

    And in this case, should the unused ports that connect to GND be configurated as analog inputs?

    Best Regards,

    Toru Kimura

  • 0 in reply to ? ??
    TI__Expert 6790 points

    Hi Kimura-san,

    Yes, the pins can be configured as analog inputs, which they are by default. They can be connected directly to ground.

    Regards,
    Joel

  • +1 in reply to Joel Meraz
    Prodigy 160 points

    Hi Joel-san,

    Thank you for your reply.

    I understood it.

    Best Regards,

    Toru Kimura