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TCA9555: Power Consumption

GoodSirEric
Prodigy 60 points
Part Number: TCA9555

Our TCA9555PWR is consuming a mystery 2.1mA. We can remove it from the board and see the overall current drop by that much.

The datasheet indicates that in operating mode or when there are high inputs, the current is a few uA. When there are low inputs, the datasheet says ithe part would would consume ~0.6mA. Is this actually the case that a low input would cause the part to consume > 1mA?

We assumed when selecting the part that this part of the datasheet was a typo and that the part should consume only uA. 

  • 0
    Prodigy 60 points

    I did not account for two 10k pull-up resistors, consuming 0.66mA. And the internal pull-ups of the TCA9555 we did not realize were ~100k, leading to another ~0.4mA-1mA. 

    This still leaves ~0.5mA unaccounted for. Does the "Standby mode" quiescent current with low inputs include the IIL Input low leakage current, or is the Quiescent current considered separately?

  • 0 in reply to GoodSirEric
    TI__Guru 73331 points

    Hey Eric,

    Would it be possible for you to share your schematic around our device?

    If you have any floating pins on inputs, such as SDA/SCL (pull up to a Vcc rail which is not powered but TCA9555 is powered) this can cause leakage current.

    Are you also using the device as an output when you are measuring the consumption current? You shouldn't see consumption current from the 100k internal pull ups if you are not driving the line low externally or pulling low on the GPO.

    Thanks,

    -Bobby