Patent ID: 8423809

Claim:
An access control apparatus of a data storage device, comprising: a first connecting unit configured to be removably connected with a host device, perform data transmission through a first data-transmission line, and be supplied with power through a first power-transmission line; a second connecting unit configured to be removably connected with the data storage device, perform data transmission through a second data-transmission line, and supply power through a second power-transmission line; a data transfer processing unit configured to perform data transfer between the host device and the data storage device; a power consumption measuring unit configured to measure power supplied from the host device through the first power-transmission line; and a power-transmission capability monitoring unit configured to control the data transfer processing unit in accordance with power consumption measured by the power consumption measuring unit; wherein the data transfer processing unit includes a test data communication unit that performs transmission of test data to the host device through the first data-transmission line while changing power load in multiple stages, in a manner to be free from supplying power to the data storage device, and the power-transmission capability monitoring unit includes a storing unit that stores a maximum power-transmission power at which the test data communication unit can perform data transmission at a highest power load, in response to a measurement result of the power consumption measuring unit, and controls the data transfer processing unit such that the data transfer processing unit starts data transfer between the host device and the data storage device and temporarily stops an access to the data storage device in a period during which power consumption measured by the power consumption measuring unit exceeds the maximum power-transmission power stored in the storing unit.