Patent ID: 8067861

Claim:
An interface device that is used in a slave device connected to a host device to transmit and receive data and/or a command to and from the host device, comprising: a clock input unit that receives input of a clock signal on a clock bus from the host device for transmitting and receiving the data and/or the command to and from the host device; a terminal group including one or more input/output terminal units that transmits and receives the data and/or the command to and from the host device using one of a first interface voltage and a second interface voltage on a data bus and/or a command bus; and an interface voltage switching unit that selects one of the first interface voltage and the second interface voltage and switches the interface voltage on the clock, the data and the command bus used for transmitting and receiving the data and/or command to and from the host device to the selected one of the first and second interface voltages, wherein the interface voltage switching unit includes a control unit, and an input/output terminal control unit controlled by the control unit, the input/output terminal control unit (1) controls the one or more input/output terminal units to an output state at a predetermined voltage level when the interface voltage used for transmitting and receiving the data and/or command to and from the host device is to be switched after receiving an instruction from the host device to switch the interface voltage, and (2) controls the one or more input/output terminal units to switch from the output signal state at the predetermined voltage level to an input signal state when an interface voltage in the slave device has been switched to the selected interface voltage.