Bidirectional input/output circuit

Level-shifting devices and methods allow signals to be passed between input/output (I/O) ports. One such device comprises a first output driver (108) that drives a first I/O port (122) in response to a first control signal (110 out). A second output driver (120) drives a second I/O port (102) in response to a second control signal (116 out). A first comparator circuit (110), responsive to a first reference voltage (Vref1) and a voltage at the first I/O port (122), generates the second control signal. A limiter circuit (106) limits driving of the first I/O port (122), by the first driver (108), to a limiting voltage (Vol) that responsive to a the first I/O port (122) over a first range of signaling voltages, and constrained to a set value over a second range. A voltage reference generating circuit (114) generates a second reference voltage (Vref2). A second comparator circuit (116) generates the first control signal in response to the second reference voltage and the second I/O port (102).