1. An integrated circuit having I/O pin interface circuits providing digital and analog functions, comprising: digital circuits and at least one analog circuit formed on said integrated circuit; a plurality of contact pads formed on said integrated circuit; a multiplexer circuit; a plurality of I/O pin interface circuits, each I/O pin interface circuits associated with a respective said contact pad, each said I/O pin interface circuit coupling digital signals between the respective contact pads and said digital circuits, at least some of said I/O pin interfaces coupling analog signals between said contact pads and said multiplexer circuit; and said multiplexer circuit coupled between said I/O pin interface circuits and said analog circuit for selectively coupling signals between said analog circuit and said I/O pin interface circuits.