Data access device for working with a computer of power off status

A data access device for working with a computer, the computer having a power supply device, a motherboard, and a data storage device, the data access device comprising:

• a power multiplexer, for establishing power channels according to a control signal to supply power to the data access device;
• a DC to DC converter for converting standby power provided by the power supply device and applying the converted power to the data storage device via a power multiplexer;
• a serial bus signal to storage interface signal controller, for converting a storage interface signal of the data storage device into a serial bus signal, or converting a serial bus signal inputted from an external device into the storage interface signal of the data storage device;
• a data storage interface signal multiplexer, for establishing a data transmitting channel according to the control signal, so as to select the motherboard or external device to access the data storage device 13;
• and
• a path controller electrically connected to the power supply device, the power multiplexer, the serial bus signal to storage interface signal controller, and the data storage interface signal multiplexer,
• wherein, when detecting that an external serial bus signal is inputted to the serial bus signal to storage interface signal controller, the path controller outputs the control signal to control the power multiplexer for converting power and to control the data storage interface signal multiplexer to switch the data transmitting channel.