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Original question:

TPL5100: TPL5100 used as a really long Watchdog timer.

TPL5100: TPL5100 as a watchdog

Darshan Shah1
Prodigy 195 points
Part Number: TPL5100
Other Parts Discussed in Thread: TPL5000, , TPL5110, TPL5010

I am using TPL5100 as a watchdog. I have configured D0,D1,D2 as high so I have 1024s timer. Currently, my application is sending DONE pulse (High->Low) every 20 seconds and I expect after 1024 sec, it will not set RSTn pin. In my case, irrespective of DONE signal, after 1024s out HW is getting reseted due to TPL5100.

Can you provide more details how we can implement watchdog using TPL5100.

Update: We have TPL5000 as well and with the same implementation, we are not seeing reset signal and watchdog functionality works fine with it.

So what needs to be change for TPL5100?

  • 0
    TI__Mastermind 19780 points
    Hi Darshan,

    What is the width of the DONE pulse you are sending to the TPL5100?

    Can you provide a schematic? Are you using TPL5100 or TPL5000? TPL5100 doesn't have a RSTn pin.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Prodigy 195 points

    Hi Rob,

    Thank you for your response.

    We are sending DONE(ON->1sec period->OFF) signal every 10 second.

    We have HW in which we can use both one by connecting different resistor value.

    Below is the schematic of the connection of our HW with TPL5100,

  • 0 in reply to Darshan Shah1
    TI__Mastermind 19780 points
    Darshan,

    The behavior of the DRV pin can be seen in the datasheet figure 6. Your description of RSTn not toggling is difficult to understand because I don't see a RSTn signal in your schematic.

    In the TPL5100, the DRV pin will toggle regardless of DONE pulse. If you don't receive a valid DONE pulse, the DRV pin will remain high for the entire delay period of 1024s.

    TPL5000 is a better watchdog as the RSTn signal will NOT toggle if DONE is received.

    What is the voltage level of the DONE pulse? It may exceed VDD + 0.3V if it is a 3.3V level signal. Your VDD looks like it is running at ~2.9V with the diode. I don't think this is causing your problem, but it is a reliability concern in the future.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Prodigy 195 points

    Hi Rob,

    Thank you for your response. Now I understand it better. in TPL5100, once DRV signal receive we need to give DONE signal. And in TPL5000, RSTn signal can be reset as soon as we provide DONE signal. So TPL5000 can works as watchdog.

    And for sorry confusing with RSTn. I meant to DRV for 5100 and RSTn for 5000.

    One more question, our requirement is to have more than 5 minutes timeout and with TPL5000, we can have maximum 64s timeout. Can you please suggest IC which can be used the same as TPL5000 but with more timeout?

    Also will TPL5010 or TPL5110 can work in our use-case?

  • 0 in reply to Darshan Shah1
    TI__Mastermind 19780 points
    Hi Darshan,

    Yes, for watchdog function with a wide, highly configurable time period, the TPL5010 is best selection.

    Best Regards,