I have a project on which I used two mcp617's for the purpose of buffering a signal. Inputs An1, An2, and An4 work as expected, but An3(J7 connector) does not. An incoming signal level of 4.4V on pin 3 of U22(tested with 3.3v as well) is outputting 2.8V on pins 1-2. I have tested this across numerous different boards and chips with the same result. I also have double checked that there is no load on the output
At this point I am unable to find the difference in layout or schematic between these circuits. The MCP617 is listed as unity gain stable as well.
MUCH larger version of circuit diagram here - Imgur saves uploaded files at larger sizes than it displays.
Update: After going through all boards, it seems this is indeed happening to all devices somewhat randomly, probably due to running these outside their characterized parameters.