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TCA9539: two questions on TCA9539

Shu-Cheng LIN
Guru 11785 points
Part Number: TCA9539

Hi Sirs,

Sorry to bother you.

We have two questions on TCA9539.

1. The GPIO DC level is be followed VCC, right?

2. If we connect GPIO to interrupt, does IC could detect interrupt different state then pass to SoC across Pin 1?

  • 0
    TI__Mastermind 23116 points
    Hello Shu-Cheng,
    1. Yes, the IO is referenced to Vcc, so high is Vcc and low is ground.
    2. I believe you are asking if you can connect the INT pin of TCA9539 to one of the IO of the TCA98539. Is that correct? If so, yes you can do this. Are not going to use the INT to wake up the micro and do operation? Are you planning on using a polling architecture instead and just read the state of that INT using IO of TCA9539? If so, than you can do that. I guess that saves an IO on your micro, but now you are not interrupt driven. Up to you. Either way is fine.
    -Francis Houde
  • 0 in reply to fhoude
    Guru 11785 points

    Hi Sirs, 

    Thanks for your reply.

    Our schematic as below

    We need confirm one thing.

    Our Pin 16 is connect ”NVSR_INT” input
    If Pin 16 have change different state then TCA9539 will proactive notification our system, right?

  • 0 in reply to Shu-Cheng LIN
    TI__Mastermind 23116 points
    Hello Shu-cheng,
    Where is the pull up resistor on the INT pin? You need that because the INT pin is open drain and that is the only way you can tell if it is logic high or low. High is pullup with FET OFF and low when INT is activated (in other words FET is turned on and pulled low).

    Assuming you have an pullup on the INT pin than yes, the TCA9539 will notify you (the master) that you have a state change on any of the input pins of the TCA9539.
    -Francis Houde