• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 394 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25120A: Delay required from power applied to start of I2C communication?

Denis Bohm
Intellectual 375 points
Part Number: BQ25120A

I've found that if we try to communicate with the BQ25120A before 70 ms after our MCU starts up then the communication fails.  I don't see anything in the data sheet about this.  Is this specified somewhere? If not are the min/typ/max values available elsewhere?

  • 0
    TI__Genius 12485 points
    Denis,

    Good catch. You will have to wait for twake1 timer before start of communication. Let me make it clear on the datasheet. thanks for pointing.
  • 0 in reply to Gautham
    Intellectual 375 points

    Thanks for the info.

    The spec for twake1 is min 80 ms and max 1 s.  One second seems like a long delay on startup.  I suppose the typical value is much closer to the 80 ms?

    Seems like the only way to minimize delay would be to loop and try to communicate every few ms until success.  Sound right?  Or is there some other way to tell when communication is available?

  • 0 in reply to Denis Bohm
    TI__Genius 12485 points
    Denis,

    It will be the lower setting of twake1 so 80ms. I will add a note for an expected variation of a max of 20ms. So 100ms should be an overkill (more than sufficient) when from the SYS coming up.

    You could read register 0x00 to make sure the device is up. I like your idea. You could probably initialize your peripherals, timers, gpios etc (depending on how long that takes) then loop in chunks of 10ms to make sure you can read.


    regards,
    gautham