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TCA6424A: Default state of INT and I/Os PU values

RNJ
Prodigy 46 points
Part Number: TCA6424A

Hello,


I using a TCA6424A to read inputs and I have some questions:


1) In the datasheet, I did not find after doing a RESET pulse, what will happens with the INT pin, if INT is asserted and the device is reseted, will the INT be cleared?


2) In the datasheet says "Resetting the interrupt circuit is achieved when data on the port is changed to the original setting or when data is read from the port that generated the interrupt"

About this original setting, how long takes it to consider an original setting? If I switched the input high -> low , low -> high, is there any time to respect this "original setting", or the device will consider the last read as original setting and no matter how much time occurs the change, if turned it back, the INT will be cleared?

3) In this topic e2e.ti.com/.../518072 saying that unconnected pins should be left unconnected, but for "extra caution" you can PU then externally. Where in the datasheet says about this internal pull up? How strong is this pull-ups? Are they referred to Vccp?

  • 0
    TI__Guru 62920 points
    Hi Ricardo,

    These are good questions, and sorry I don't have immediate answers. We will look into this and get back to you next week.

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    Prodigy 46 points
    Thank you for your report Max! I will be waiting for these answers!!!
  • 0 in reply to RNJ
    TI__Guru 62920 points
    Ricardo,

    Sorry for the delay, but I have some answers for you now:

    - The interrupt will be cleared by a reset.

    - The "original setting" in this case means the one that was last read, so there isn't a certain amount of time needed to "lock in" a state.

    - I believe the previous thread you mentioned is not correct. There may be some small leakage current in those ports that would cause the voltage to settle to a high or low level, but as far as I can tell there is no intentional pull-up or pull-down. I would recommend to use an external pull-up or pull-down so that these pins remain at a well-defined state.

    I hope this info is useful to you; please let me know if you have any further questions.

    Regards,
    Max