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TPL5010 WAKE pin - is it necessary to use it?

Karlis Tucs
Expert 1385 points
Other Parts Discussed in Thread: TPL5010

Hello all. This is my first time in Clock and Timing forum.

I was wondering do I have to use the WAKE pin on TPL5010?

Example: Can't I just make my Single Board computer send the DONE pulse every minute to Watchdog and leave WAKE pin open? 

I was wondering if this DONE must come after the WAKE or  can my Single board computer just spam these DONE pulses and if SBC hangs and stops sending these, then it gets reseted.

Thanks in advance!

  • 0
    TI__Genius 9655 points

    Hi Karlis,

    Each Wake pulse needs to be followed by a Done pulse. If the TPL5010 does not receive a DONE after the WAKE it resets your SBC. So it means that your SBC has to handle the WAKe signal too.

    Regards,

    Domenico

  • 0 in reply to domenyko
    Prodigy 175 points

    Hi Domenyko,

    In the TPL5010 datasheet it says:

    "The DONE pin is driven by a µC to signal successful processing of the WAKE signal. The TPL5010 recognizes a

    valid DONE signal as a low to high transition; if two or more DONE signals are received within the time interval,

    only the first DONE signal is processed."

    Can't we use a frequency on the DONE line that is at least twice the frequency of the WAKE signal and thus make sure we extinguish the RESET signal always unless there is an issue and the uC is stuck?

    I know this is not the intended design but the idea seems quite valid, especially that we have not found any watchdogs from TI with only DONE signal.

    Best,

    Nizar 

  • 0 in reply to Mohamad Nizar Kezzo
    TI__Genius 9655 points

    Hi Nizar,

    even if the device has not been designed for this purpose, your idea is valid.

    the device will recognize the first done after the wake signal is asserted. Please check the table in section 7.6 timing requirements to check the valid window for the done signal (parameter tDDONE).

    regards,

    Domenyko

  • 0 in reply to domenyko
    Prodigy 175 points
    Thanks for the help Domenyko. Given that, is it possible to leave WAKE pin unconnected? Or should be pulled down with a proper resistor (i.e. resistor value calculated depending on pin leakage current)?
  • 0 in reply to Mohamad Nizar Kezzo
    TI__Genius 9655 points
    Hi Nizar,
    the WAKE is a push pull so you can leave it unconnected, in this way you minimize the consumption. If you do not like floating pin connect it to GND through a resistor of tens Kohm.
    regards,
    Domenyko
  • 0 in reply to domenyko
    Prodigy 175 points
    Thanks for the help Domenyko!