Patent ID: 8531228

Claim:
A bidirectional level-shifting device for passing signals between input/out (I/O) ports having different signaling levels, the device comprising: a first output driver configured and arranged to drive a first I/O port in response to a first control signal; a second output driver configured and arranged to drive a second I/O port in response to a second control signal; a first comparator circuit, responsive to a first reference voltage and a voltage at the first I/O port, to generate the second control signal; a limiter circuit configured and arranged to limit driving of the second I/O port, by the second driver, to a limiting voltage that is adjusted according to a signaling level of the second I/O port over a first range of signaling voltages, and constrained to a set value over a second range of signaling voltages; a voltage reference generating circuit configured and arranged to generate a second reference voltage; and a second comparator circuit configured and arranged to generate the first control signal in response to a comparison between the second reference voltage and the second I/O port; and wherein the limiter circuit includes a voltage divider network that adjusts the limiting voltage according to the signaling level of the second I/O port and a diode that has a forward bias drop that constrains the limiting voltage over the second range of signaling voltages.