Keith's observation is interesting.? Since we know you are getting voltage at source of Q111 (per your measurement) it means L102 is not open.? But it could be shorted (burned), or maybe R114/Q110 are not working.? Did you ever measure the voltage at LIN_REG_EN?? I don't know the details of how the processing code works, but the processor could be in a state where it is not yet turning LIN_REG_EN off, since it isn't getting the correct response from the smps.? Replacing D109 and the Q111 drain may cause some of these things to work, but PLEASE do it at about 7V with a current limit of about 250mA, so it won't burn D109 again if there is still a fault somewhere.
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And one other thing still bothers me, which is independent of D109 and the Q111 drain.? If your DMM measures 10.6V at source of Q111, and 3.3V at ADC_3V3, something is broken in the circuit.? By circuit definition, the value at ADC_3V3 must be almost exactly 1/2 the value? at the source of Q111.? If it is not, something must be shorting across one of the two resistors of the voltage divider R110/R112, perhaps something shorting at the ADC_3V3 node, or a wrong value resistor is installed.? And if this isn't fixed, the smps won't work properly.
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Stan KC7XE
