Disclosed examples include ICs and general-purpose I/O circuitry to facilitate interfacing of the IC with a variety of external circuits operating at different supply voltages, in which an integer number N supply drive circuits are individually coupled with a corresponding supply voltage node and selectively connect the corresponding supply voltage node to a general-purpose output node based on a supply drive control signal to allow programmable interfacing of individual general-purpose output pads or pins of the IC with an external circuit at the appropriate signal level.