Jeff Barnhouse

MCP52258 Protecting inputs to unpowered chip

Discussion created by Jeff Barnhouse on Nov 19, 2009
Latest reply on Nov 19, 2009 by Stan Chernikov

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. 

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