Patent ID: 7545171

Claim:
An input/output device comprising: a level shifter configured to convert an input signal of a first voltage into an output signal of a second voltage; and an output driver configured to operate in response to the output signal, wherein the level shifter is configured to generate the output signal with a predetermined level when the first voltage is interrupted, wherein the level shifter comprises: a floating protection circuit supplied with the second voltage and to operate in response to the input signal; and a level shifting circuit configured to generate the output signal of the second voltage in response to an output of the floating protection circuit, wherein the floating protection circuit is configured to prevent an input of the level shifting circuit from being floated when the first voltage is interrupted, and wherein the floating protection circuit comprises: a first resistor connected between a first input of the level shifting circuit and the second voltage; an NMOS transistor connected between the first input of the level shifting circuit and a ground voltage, responsive to the input signal; and a second resistor connected between the ground voltage and a second input of the level shifting circuit supplied with the input signal.