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.

TPS3850: Watchdog reset with manual reset only

Part Number: TPS3850
Other Parts Discussed in Thread: TPS3823, TPS3820, TPS3828

Hi,

I'm looking for a watchdog device with following functionality.

From the processor a clock signal is provided. When the clock stops the watchdog needs to give out a reset.

When the clock comes back the reset output is not allowed to be cleared.. It needs to stay in reset till a separate manual reset is given to the watchdog in addition to the clock signal

Do we have this functionality ? Only found that the reset is cleared when the clock from the uC comes back

Best wishes,

Olrik

  • Olrik,

    You are in need of a "latching" watchdog. We have came up with a design to latch our TPS3850 device and have created a blog to explain the design. The blog is in final revision so not currently on ti.com but I can send you the latest version. Please email me directly at michaeldesando@ti.com

    If you just want to see the design, it uses an open-drain buffer from the /WDO pin to the Crst pin shown below:

    Another technique for latching also explained in the blog is to use a device with /MR (manual reset). This would work for devices like TPS3820, TPS3823, and TPS3828 which also have watchdog inputs. For these devices, the /RESET output will latch for undervoltage conditions or watchdog conditions.

    -Michael

  • TPS3850 Latching watchdog:

    Latching /RESET from undervoltage or watchdog uses TPS3820, TPS3823, TPS3828 with configuration shown below:

    -Michael