MCP52258 Protecting inputs to unpowered chip

[RxScram]

Hi All,

I'm  currently working on a design with the 52258.  I am trying to protect the GPIO lines in the event of an unpowered processor.  (This is not a normal operating condition, but is a failure mode that must be protected against.  Specifically, I am protecting against a double problem... processor unpowered, with user error in installing a cabling harness such that 48V is applied to a pin's input path)  

The max current for a single pin, according to the data sheet, is 25 mA.  However, this is for a powered chip.  Does anybody have advice on what the max current should be for a pin on an unpowered chip?

I can try to rephrase the question, if necessary. 

[scifi]

I consulted the datasheet and I couldn't find the place where it says that the 25 mA limit is for powered state only. Common sense suggests that this limit applies to unpowered state as well.

You should probably use zener diodes (and maybe regular diodes too) to limit voltages, and resistors to limit currents. Details will depend on the exact fault conditions you are protecting against.