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TL1963A: output have 1~3volt when SHDN pin is 0V

NObody
Expert 1100 points
Part Number: TL1963A

Sorry to bother.

application condition as below.

Vin=20V, SHDN pin=0V, Out pin can measure 2.45V

Vin=15V, SHDN pin=0V, Out pin can measure 1.45V

is it correct?? 

  • 0
    TI__Genius 14245 points

    Hi,

    There are a few things that I can think of that may cause the output of an LDO to be above 0V when disabled:

    1. If the load powered by the LDO is also disabled so that there is a light load, then the voltage measured on the output may simply be the residual charge of the output capacitor. In this case the output will continue to discharge as more time passes, the lower the load or larger the capacitor the longer the discharge time will be. 
    2. If the device was damaged by an overvoltage event it's possible that there is some leakage from Vin to Vout causing the output to be above 0V. I've included a screen shot of the Abs Max table for your convenience. 
    3. If the LDO is powering a device with multiple rails and the LDO is disabled but the other rails are not, the device being powered may have internal connections between the rails which causes the LDO's output to be pulled above 0V (could be a diode connecting the rails providing a strong pull up or it could be leakage current providing a fairly week pull up). 

    -Kyle