• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 161 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.

TPS3435: TPS3435 is disabled during reset ?

Toshiaki Kojima
Prodigy 10 points
Part Number: TPS3435

Tool/software:

I would like to use the TPS3435 for watch dog timer reset.

My concern is whether or not I need to take any measures to disable the TPS3435 not to work during the reset (until the application software starts to issue watchdog pulses).

I suppose that once the TPS3435 detects watchdog pulse input failure, it outputs a reset signal to the CPU and do nothing anymore until it detects the first watchdog pulse 

after the CPU recovers.

Could you please advise if my understanding above is correct ?

  • 0
    TI__Genius 11590 points

    Hi Toshiaka-san,

    The TPS3435 has a built in startup delay feature to avoid resets during the boot-up/initialization period. 

    For cases where no pulse is provided to the WDI within the startup delay period the WDO will assert for the defined output assert time or latch depending on the configuration.

    Thanks,
    Joshua

  • 0
    Prodigy 10 points

    Thank you for your answer. Do you mean the power-on sequence by "Startup" ? Not applicable to the reboot of the CPU when powered on already  ?

  • +1 in reply to Toshiaki Kojima
    TI__Genius 11590 points

    Hi Toshiaka-san,

    The startup delay will be present after every power cycle (startup) or WDO assertion event of the WDO.

    Thanks,
    Joshua

  • 0 in reply to Joshua Garcia
    Prodigy 10 points

    Sorry, I have one more question.

    In Section 7.3.1.2, I found the follwoing paragraph:
    Quote:
    Pinout options A, B offer watchdog timer control using a capacitance connected between CWD and GND pin.
    A capacitance value higher than recommended or connect to GND leads to watchdog functionality getting
    disabled.
    Capacitance based disable operation overrides the other two options mentioned above.
    Changing capacitance on the fly does not enable or disable watchdog operation.
    A power supply recycle is needed to detect change in capacitance.
    Unquote:

    I would like to use the pinout option "A", but there is no WD-EN pin in this package.
    I need to disable/enable the watchdog function during operation, using a GPIO port from the microprocessor.
    I thought I could disable/enable by toggling between the capacitor and GND on the CWD pin during operation.
    However, this toggling does not become effective until cycling power according to the datasheet.
    Is there any other way to disable/enable the watchdog function during operation ?

  • +1 in reply to Toshiaki Kojima
    TI__Genius 11590 points

    Hi Toshiaka-san,

    There is no other way to disable/enable the A pinout watchdog other than to power cycle after changing the CWD pin. I would recommend using our other adjustable capacitance B pinout which offers enable and disable control through the SET1 and SET0 pins. 

    Thanks,
    Joshua