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Original question:

TPS3851: Schematic review

TPS3851: Question Asking

Jason Ciou
Expert 3600 points
Part Number: TPS3851

Hi Team,

My customer has some question about TPS3851. Could you please give me some advice.

Customer request: Internal to CPU which should generate a board-wide hardware reset if not ticked in 10 to 20 seconds

So CWD pin is pull-high 3.3V for programing watchdog function

Below is updated schematic.

  • +1
    TI__Intellectual 1210 points

    Hi Jason,

    On this schematic there are some resistors with an '@' symbol, do you know if these resistors are planned on being populated?

    The reason why I ask is because on the CWD pin there is both a 10K pullup resistor to the 3.3V rail, as well as the capacitors to GND, when really there should be only either one.

    The timing based on the calculations is accurate for a ~77s watchdog timer, but given the customer request for a tick between 10-20 seconds, the 77 second timer could be lowered.

    Also, there is another open E2E thread with a similar question asked? Did you mean to ask this question again here? If not, would you mind closing the other thread?

    Regards,

    Jake

  • 0 in reply to Jake F
    TI__Expert 3600 points

    Hi Jack,

    The "@" symbol means there is no component on the circuit. so the Pin 8 is tied the 10k resistor to ground.

    If my customer want to tick between 10-20 seconds, how should they do to tune this value? change the value of capacitor?

    I will closed the other E2E questions.

    Jason