Device with power-off charging capability

1. An electronic device comprising:

power control circuitry that charges a battery device with power supplied from a power supply line of a cable;

voltage maintaining circuitry that maintains a predetermined voltage of a specific line of the cable by creating a connection between the power supply line and the specific line, in a case where an external apparatus is communicably connected to and exchanges data with the electronic device via the cable in a first communication mode; and

a processor that controls the voltage maintaining circuitry so that the predetermined voltage of the specific line is maintained by the voltage maintaining circuitry, in a case where the power control circuitry is charging the battery device with power supplied from the power supply line in the first communication mode when the electronic device is changed from a power-on state to a power-off state,

wherein the processor, in a case where the external apparatus is communicably connected to the electronic device via the cable in a second communication mode different from the first communication mode, exchanges data with the external device and charges the battery device when the electronic device is in the power-on state, and displays, prior to switching the electronic device from the power-on state to the power-off state, the charging of the battery device with power supplied from the power supply line cannot by continued.

2. The electronic device according to claim 1 , wherein the specific line is a line used by the external apparatus to monitor a voltage which determines that the electronic device is connected via the external cable.

3. The electronic device according to claim 1 , wherein the specific line is a signal line in the cable.

4. The electronic device according to claim 1 , wherein the specific line is connected to the predetermined voltage when the cable is communicably connected in a specific communication mode.

5. The electronic device according to claim 1 , wherein:

the processor determines whether the external apparatus connected to the cable can supply power for charging the battery device, and

the processor controls the voltage maintaining circuitry so that the predetermined voltage of a specific line is maintained by the voltage maintaining circuitry, in a case in which the processor has determined that the external apparatus can supply power for charging the battery device.

6. The electronic device according to claim 1 , wherein the processor controls the voltage maintaining circuitry so that the predetermined voltage of a specific line is maintained by the voltage maintaining circuitry, in a case in which the battery device is being charged by the power control circuitry.

7. The electronic device according to claim 1 , wherein the processor is configured to, when the electronic device is in the power-on state, charging, and communicably connected to the external device in either the first communication mode or the second communication mode:

responsive to the electronic device receiving a user instruction instructing the electronic device to be in the power-off state, switch the electronic device from the power-on state to the power-off state.

8. The electronic device according to claim 1 , wherein the processor starts, when the external apparatus is communicably connected to the electronic device via the cable in the second communication mode, a process of setting the electronic device to the power-off state after reconnecting to the external apparatus so as to be communicably connected to the external apparatus via the cable in the first communication mode.

9. The electronic device according to claim 1 , wherein the first communication mode is an FS (Full Speed) mode of USB (Universal Serial Bus), and

the voltage maintaining circuitry maintains a state in which a D+ line of the USB has been pulled up to the predetermined voltage.

10. The electronic device according to claim 1 , wherein the first communication mode is an HS (High Speed) mode of USB (Universal Serial Bus), and

the voltage maintaining circuitry maintains a state in which a D+ line and a D− line of the USB have been pulled down to a ground level.

11. The electronic device according to claim 1 , further comprising a connection unit having a USB interface configured to receive, via the cable, in both the first and second communication modes, when the electronic device is in a power-on state, power transmitted from the external apparatus through the power supply line of the cable, and data transmitted from the external apparatus through the cable.