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TPS3850-Q1: TPS3850H33QDRCRQ1 cannot be reset

Part Number: TPS3850-Q1

Hi,

When we use the chip TPS3850H33QDRCRQ1, it will not reset without feeding the dog. What may be the problem? The schematic diagram is shown in the following figure.

Thanks!

  • Hi Jeno,

    In order to disable the watchdog SET0 = 1 (logic level high) and SET1 = 0 (logic level low). From your diagram in the green box it looks like you might be missing the SET0 = 1 (logic level high) in order to properly disable the watchdog.

    Thanks,
    Joshua

  • 1.The current problem is that it won't reset without feeding the dog. Why? Please help analyze the reason;

    2. Both CWD and CRST pins are connected to capacitors to achieve programmability. It is reasonable to say that after power on, the watchdog will reset if it times out and does not feed the dog. Why did it not reset?

  • Hi Jeno,

    Just to confirm my understanding here, when you state you are not "feeding the dog" you mean you are not inputting anything to the WDI pin?

    Can you confirm the voltages on the SET0 and SET1 pins? Also when you are attempting to cause a WDO reset, is the voltage above the threshold condition + hysteresis (RESET in a non-active state = HIGH)?

    Thanks,
    Joshua

  • Hello,

    The WDI pin has no input and remains low, Set0 and Set1 remain high, and the WDO pin remains high;

    Please help analyze the reason;

    Thanks!

  • Hi Jeno,

    The WDI pin has no input and remains low, Set0 and Set1 remain high, and the WDO pin remains high;

    You stated that both SET0 and SET1 remain high, as previously stated in order to disable the watchdog SET0 = 1 (logic level high) and SET1 = 0 (logic level low). Please have SET1 go low.

    Thanks,
    Joshua

  • The problem now is that I don't want to disable the watchdog. I want to use the watchdog function, but the problem is that when the watchdog is not disabled, it won't reset without feeding the dog

  • Hi Jeno,

    Could you please remove C58 capacitor and ground connection on the reset pullup, I believe this is throwing off your WDO reset pulldown.

    Thanks,
    Joshua