With the device off and no voltage on the input. Can you supply a voltage on the output of the device? This will be a output from another regulator. Will there be leakage current into the device or will it malfunction?
Here is my setup:
TPS54325: regulate 12V down to 5V with a max current of 2A.
Other regulator: regulate 50V down to 5V with a max current of 2A.