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LP2954A: no clear definition of what max output voltage can be present in the lack of an input voltage

Part Number: LP2954A

The datasheet states that the output voltage can be programmed from 1.23 to 29 volts.  In section 7.3.3 (Output Isolation) the following is stated: "The regulator output can be left connected to an active voltage source (such as a battery) with the regulator input power turned off, as long as the regulator ground pin is connected to ground. If the ground pin is left floating, damage to the regulator can occur if the output is pulled up by an external voltage source."  So my question is what is the max voltage that can be left at the output when there is no input voltage.  An absolute max rating if you will. 

  • Hi Jon,

    Unfortunately we don't have any more information than what is in the datasheet because this is a legacy National Semiconductor device. The output pin for sure can withstand up to 29V without damage, but whether 29V an be applied at the output when there is no input is not clear. I would recommend ordering some samples and performing bench measurements to verify.