We now use a switch button control chip LTC29511TS8. The current phenomenon is that the Pb pin button does not trigger, but is always low, only about 0.5V. The EN pin is not low, the button switch does not work, the MOS does not work, and the s ubsequent stage does not work. Please help analyze what the problem is

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    •  Analog Employees 
    on Oct 7, 2021 2:44 AM

    Hi Dongdognjun,
    From what I can tell, the problem is your PB# pin is stuck low at 0.5V.
    EN# will only change state when PB# sees a falling edge.
    What are you using to pull PB# low? A uP I/O pin or tactile switch?

    Since there doesn't seem to be a spice model for the LTC2951 to simulate your circuit, I built it using a DC826C-B.
    Here is a schematic with node names corresponding to the scope-shot.

    The circuit seems to behave as intended.