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Original question:

TLIN1441-Q1: Questions about software reset and watch dog timer

TLIN1431-Q1: TLIN1431-Q1

Marian Neacsu
Prodigy 30 points
Part Number: TLIN1431-Q1

Hello,

I plan to use TLIN 1431 to supply a ECU with NXP microcontroller.

I wonder how can I start programming an uC (without software inside) .

My concern is that the watchdog will trigger a reset if the uC will not trigger it.

It is a way to disable watchdog during uC programming ?

Thank you

Best regards

Marian

  • 0
    TI__Guru 65202 points

    Marian,

    Our LIN expert will be back in office tomorrow afternoon. Please expect a response by end of business 01/25/2023.

    To answer in short, the watchdog needs to be triggered at all times to use the device. Our expert can discuss more about a possible workaround.

    Regards,

    Eric Hackett 

  • 0
    TI__Mastermind 24275 points

    Marian,

    Thanks for reaching out!

    By design, the watchdog for the TLIN1431-Q1 is on upon startup. This device is uniquely situated for safety applications where the watchdog can still act to reset the microcontroller or take action in the event that the MCU fails before it is even able to configure or trigger the watchdog. However, the tradeoff is exactly what you mentioned: an unprogrammed MCU will not service the watchdog and can be subject to resets from watchdog failure outputs from the TLIN1431-Q1.

    While we have seen designers implement a few different workarounds for this while evaluating the component, there is no way to internally disable the watchdog upon startup. The only way to avoid the watchdog would be to first transition the device to Fast Mode or to issue SPI commands to disable the watchdog (in SPI control only).

    Additionally, I have seen designers place a series resistor and header/testpoint on the MCU side of the reset line which is held high during programming, effectively preventing the MCU from experiencing a reset when the TLIN1431-Q1 experiences watchdog failures. There are also additional approaches, including separating the TLIN1431-Q1 power supply during flash or disconnecting the TLIN1431-Q1 reset output from the input to the MCU (i.e. by removing a shunt/resistor).

    Best,

    Danny