Patent ID: 7773357

Claim:
An auto-detecting input circuit disposed between a supply-voltage terminal and a ground terminal, the auto-detecting input circuit comprising: a clamp coupled to the supply-voltage terminal and an output pad and configured to electrically couple the output pad to the supply-voltage terminal; a detector coupled to an input pad and configured to produce a detection signal; a voltage-divider coupled between the input pad and the output pad and configured to translate input voltage levels to output voltage levels; and a latch coupled to the voltage-divider and configured to retain a trigger signal; wherein the detector comprises: a first transistor with a source terminal coupled to the input pad, a gate terminal coupled to a drain terminal of the first transistor, and a bulk terminal coupled to a floating well; and a second transistor with a source terminal coupled to the drain terminal of the first transistor, a gate terminal coupled to both an intermediate terminal and a drain terminal of the second transistor, and a bulk terminal coupled to the floating well.