LTC4368 Random Shutdown

LTC4368-1 Random shutdown occurs approximately 20 seconds after power on. The circuit is found below. I measure 400mV and 800mV at the OV and UV pins. The gate voltage measures ~11.28V across Gate and Vout.  

I have set the resistor divider (using the datasheet's equation) OV to 36V & UV to 18V and the circuit is powered with a power supply at 28V. I am expecting a max of 200mA for my application. 

Any ideas why this event is happening 20 seconds after power on?  

I also tried back to back MOSFET configuration, as below: 

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  • +1
    •  Analog Employees 
    on Nov 24, 2020 7:33 PM 3 months ago

    When this shutdown occurs, does the output eventually turn back on? If it doesn't, that could indicate an overcurrent fault. Because you have the RETRY pin grounded, the output will stay off after the circuit breaker is tripped.

    Monitor UV, OV, and current on your scope when the fault occurs. If you don't have a current probe, you can measure the voltage difference across the sense resistor using two scope probes a math function, and see if it exceeds the 50mV threshold.

    -Aaron

  • The output does not turn back on. I find that the component must have been damaged and caused this weird action to occur. 

    Fortunately, I purchased 4 of them. I had the same event occur on 2 of 4. I assume damaged occurred when soldering the IC onto a perf board.  I also changed the circuit after getting it to work.  

    Great product! I appreciate the support. 

Reply
  • The output does not turn back on. I find that the component must have been damaged and caused this weird action to occur. 

    Fortunately, I purchased 4 of them. I had the same event occur on 2 of 4. I assume damaged occurred when soldering the IC onto a perf board.  I also changed the circuit after getting it to work.  

    Great product! I appreciate the support. 

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