Hi,
In regards to the 'S' version of the device (REF34xxS-Q1), the 'NC' pin in the datasheet is listed as 'Test pin, connect from 0V to 18V'. In the layout example on the datasheet, there is shown a trace coming out of this pin but not specified to where it is connected. What is the use of this pin? Can it be left floating or should it be tied to ground/Vcc?