Patent ID: RE40147

Claim:
A memory card device capable of being removably inserted in a host apparatus, said memory card device comprising: a nonvolatile memory device; a controller configured to execute commands supplied from the host apparatus, thereby to write data into, and read data from, the nonvolatile memory device; a clock signal generator including a PLL configured to generate a clock signal to be supplied to the controller; and a clock control unit configured to operate in a first clock control mode, wherein the clock control unit stops the operation of shuts off the clock signal outputted from the PLL, if the controller becomes idle while the memory card device is in a state in which the memory card device receives waits to receive a command concerning an access to the nonvolatile memory device from the host apparatus, and configured to operate in a second clock control mode, wherein the clock control unit shuts off the clock signal outputted from stops the operation of the PLL, if the controller becomes idle while the memory card device is in a state in which the memory card device needs does not wait to receive the command concerning an access to the nonvolatile memory device.