CHARGING CIRCUIT

• US 20100141218A1
• Filed: 02/18/2010
• Published: 06/10/2010
• Est. Priority Date: 09/04/2007
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Fujitsu Microelectronics Limited (Fujitsu Limited)
• Inventors: NAKAGAWA, Shinichi
• Granted Patent: US 8,742,730 B2
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A charging circuit that prevents a system abnormality caused by removal of a battery. The charging circuit includes a constant voltage charge controller which detects charge voltage and performs a constant voltage charging operation. A constant current charge controller detects charge current and performs a constant current charging operation. A controller controls the constant voltage charge controller to perform the constant voltage charging operation during a period from when the charge voltage reaches a fully charged voltage to when the charge current decreases to a charge completion current. The controller suspends charging the battery when the constant voltage charging operation is being performed and detects whether or not the battery is coupled to the charging circuit based on the charge voltage during the charging suspension.

Claims

1. A charging circuit that charges a battery with charge voltage and charge current, the charging circuit comprising:

a constant voltage charge controller which detects the charge voltage and performs a constant voltage charging operation;

a constant current charge controller which detects the charge current and performs a constant current charging operation; and

a controller which controls the constant voltage charge controller to perform the constant voltage charging operation during a period from when the charge voltage reaches a substantially fully charged voltage to when the charge current decreases to a charge completion current;

wherein the controller suspends charging of the battery when the constant voltage charging operation is being performed and detects whether or not the battery is coupled to the charging circuit based on the charge voltage during the charging suspension.

2. The charging circuit according to claim 1, wherein the controller controls the constant voltage charge controller and the constant current charge controller to suspend the charging at least once when the constant voltage charging operation is being performed.

3. The charging circuit according to claim 1, wherein the controller controls the constant voltage charge controller and the constant current charge controller to repetitively suspend and restart the charging a number of times when the constant voltage charging operation is being performed.

4. The charging circuit according to claim 1, wherein the controller repetitively detects whether or not the battery is coupled to the charging circuit, based on the charge voltage during the charging suspension, when the constant voltage charging operation is being performed.

5. The charging circuit according to claim 1, wherein the controller includes:

a detection circuit which detects the charge voltage and generates a detection result; and

a sequence controller coupled to the detection circuit, the constant voltage charge controller, and the constant current charge controller, the sequence controller determining whether or not the battery is coupled to the charging circuit based on the detection result of the detection circuit during the charging suspension.

6. The charging circuit according to claim 5, wherein the sequence controller controls the constant voltage charge controller to restart the constant voltage charging operation based on the detection result of the detection circuit after the charging suspension.

7. The charging circuit according to claim 5, wherein the battery is connectable to a load circuit;

the sequence controller generates a suspension signal for suspending operation of the load circuit when determining that the battery is disconnected from the charging circuit.

8. The charging circuit according to claim 5, wherein the detection circuit includes a comparator which compares a first voltage, proportional to the charge voltage, with a reference voltage and generates the comparison result as the detection result.

9. The charging circuit according to claim 8, wherein the reference voltage is set to be substantially equal to the first voltage when the charge voltage reaches a recharge voltage of the battery.

10. The charging circuit according to claim 9, wherein the recharging voltage is less than the charge voltage when the constant voltage charging operation is being performed and corresponds to the charge voltage when the constant voltage charging operation is switched to the constant current charging operation.

11. The charging circuit according to claim 5, wherein the sequence controller holds disconnected information when determining that the battery is disconnected from the charging circuit and waits before starting the charging of the battery based on the disconnected information.

12. The charging circuit according to claim 2, wherein the controller includes:

a detection circuit which detects the charge voltage and generates a detection result; and

a sequence controller coupled to the detection circuit, the constant voltage charge controller, and the constant current charge controller, the sequence controller determining whether or not the battery is coupled to the charging circuit based on the detection result of the detection circuit during the charging suspension.

13. The charging circuit according to claim 12, wherein the sequence controller controls the constant voltage charge controller to restart the constant voltage charging operation based on the detection result of the detection circuit after the charging suspension.

14. The charging circuit according to claim 12, wherein the battery is connectable to a load circuit;

the sequence controller generates a suspension signal for suspending operation of the load circuit when determining that the battery is disconnected from the charging circuit.

15. The charging circuit according to claim 12, wherein the detection circuit includes a comparator which compares a first voltage, proportional to the charge voltage, with a reference voltage and generates the comparison result as the detection result.

16. The charging circuit according to claim 3, wherein the controller includes:

a detection circuit which detects the charge voltage and generates a detection result; and

a sequence controller coupled to the detection circuit, the constant voltage charge controller, and the constant current charge controller, the sequence controller determining whether or not the battery is coupled to the charging circuit based on the detection result of the detection circuit during the charging suspension.

17. The charging circuit according to claim 16, wherein the sequence controller controls the constant voltage charge controller to restart the constant voltage charging operation based on the detection result of the detection circuit after the charging suspension.

18. The charging circuit according to claim 16, wherein the battery is connectable to a load circuit;

the sequence controller generates a suspension signal for suspending operation of the load circuit when determining that the battery is disconnected from the charging circuit.

19. The charging circuit according to claim 4, wherein the controller includes:

a detection circuit which detects the charge voltage and generates a detection result; and

a sequence controller coupled to the detection circuit, the constant voltage charge controller, and the constant current charge controller, the sequence controller determining whether or not the battery is coupled to the charging circuit based on the detection result of the detection circuit during the charging suspension.

20. The charging circuit according to claim 19, wherein the sequence controller controls the constant voltage charge controller to restart the constant voltage charging operation based on the detection result of the detection circuit after the charging suspension.