BATTERY CHARGER FOR PORTABLE ELECTRONIC EQUIPMENT

• US 20110241627A1
• Filed: 04/01/2011
• Published: 10/06/2011
• Est. Priority Date: 04/06/2010
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: ON Semiconductor Trading, Ltd (ON Semiconductor Corporation)
• Inventors: ARAI, Nobuhiro, Yamada, Susumu
• Granted Patent: US 9,142,985 B2
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 9/007 Detection of the absence of a load

Abstract

There is offered a battery charger for a portable electronic device that has a simple structure and is capable of detecting that the portable electronic device is connected to the battery charger. A first power supply line is connected to a positive terminal (+) of a rechargeable battery, while a ground line is connected to a negative terminal (−) of the rechargeable battery. An output transistor is connected between the first power supply line and a second power supply line. The output transistor is connected to a Vbus terminal of a USB connector through the second power supply line. A controller outputs a voltage of an H level to the Vbus terminal to detect a change in a voltage at the Vbus terminal, and judges whether the portable electronic device is connected to the USB connector based on a result of the detection. The controller turns the output transistor on when the portable electronic device is judged to be connected to the USB connector.

Claims

1. A battery charger for a portable electronic device, comprising:

a power supply;

a power supply line connected to the power supply;

a ground line connected to the power supply;

a USB connector comprising a Vbus terminal;

a switching device connected between the power supply line and the Vbus terminal; and

a controller configured to perform a first detection to detect a change in a voltage at the Vbus terminal by outputting a first voltage to the Vbus terminal, to judge whether the portable electronic device is connected to the USB connector based on a result of the first detection, and to turn on the switching device when the controller judges that the portable electronic device is connected to the USB connector.

2. The battery charger for the portable electronic device of claim 1, wherein the controller judges that the portable electronic device is connected to the USB connector when the voltage at the Vbus terminal changes from the first voltage by a predetermined amount of voltage after outputting the first voltage to the Vbus terminal.

3. The battery charger for the portable electronic device of claim 1, wherein the controller performs a second detection to detect a change in the voltage at the Vbus terminal by outputting a second voltage that is different from the first voltage to the Vbus terminal when the controller judges that the portable electronic device is not connected to the USB connector based on the result of the first detection, judges whether the portable electronic device is connected to the USB connector based on a result of the second detection, and turns on the switching device when the controller judges that the portable electronic device is connected to the USB connector.

4. The battery charger for the portable electronic device of claim 1, wherein the ground line is connected to a ground terminal of the USB connector, and the controller judges whether the portable electronic device is disconnected from the USB connector based on a current flowing through the ground line.

5. The battery charger for the electronic device of claim 1, wherein the ground line is connected to a ground terminal of the USB connector, and the controller judges whether charging a rechargeable battery in the portable electronic device is completed based on a current flowing through the ground line.

6. The battery charger for the portable electronic device of claim 1, further comprising a resistance bridge circuit comprising first and second resistors connected in series and third and fourth resistors connected in series and a voltage output portion outputting a voltage to a connecting node between the second and fourth resistors, wherein an end of the first resistor and an end of the third resistor are connected to the ground line, a connecting node between the first and second resistors is connected to a first data communication terminal of the USB connector and a connecting node between the third and fourth resistors is connected to a second data communication terminal of the USB terminal.

7. The battery charger for the portable electronic device of claim 1, further comprising a DC-DC converter converting an output voltage of the power supply into a desired voltage and outputting the desired voltage to the Vbus terminal through the switching device, wherein the controller puts the DC-DC converter into operation when the controller judges that the portable electronic device is connected to the USB connector.

8. The battery charger for the portable electronic device of claim 1, wherein the power supply comprises a relay switching between turning on and off of an AC power supply, a rectifier rectifying an AC voltage supplied through the relay, a DC-DC converter converting an output voltage of the rectifier into a predetermined DC voltage and a backup capacitor being charged through the DC-DC converter, wherein the controller operates on a voltage of the backup capacitor and charges the backup capacitor through the rectifier and the DC-DC converter by turning the relay on when the voltage of the backup capacitor is reduced to a voltage lower than a predetermined voltage.

9. The battery charge for the portable electronic device of claim 8, wherein the controller puts the DC-DC converter into operation by turning the relay on when the controller judges that the portable electronic device is connected to the USB connector.