System and method for battery charging

• US 20090009141A1
• Filed: 07/05/2007
• Published: 01/08/2009
• Est. Priority Date: 07/05/2007
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Li, Guoxing
• Granted Patent: US 8,222,869 B2
• Time in Patent Office: Days
• US Class Current: 320/141
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process

Abstract

A charging circuit includes a pulse generator and a controller coupled to the pulse generator. The pulse generator is used to generate a plurality of pulses to control a charging switch. The controller is used to control a pulse density of the plurality of pulses. A charging current flowing through the charging switch can be adjusted according to the pulse density.

Claims

1. A charging circuit comprising:

a pulse generator operable for generating a plurality of pulses to control a charging switch; and

a controller coupled to said pulse generator operable for controlling a pulse density of said plurality of pulses, wherein a charging current flowing through said charging switch is adjusted according to said pulse density.

2. The charging circuit as claimed in claim 1, further comprising:

a charge pump coupled to said pulse generator operable for receiving said plurality of pulses and for generating a driving signal which controls said charging switch.

3. The charging circuit as claimed in claim 1, wherein said pulse generator comprises a pulse density modulation pulse generator.

4. The charging circuit as claimed in claim 1, wherein said controller comprises a processor.

5. The charging circuit as claimed in claim 1, wherein said controller monitors said charging current.

6. The charging circuit as claimed in claim 1, wherein said controller monitors a battery voltage of a battery pack charged by said charging current.

7. The charging circuit as claimed in claim 1, wherein said controller monitors a cell voltage for each cell of a plurality of cells charged by said charging current.

8. The charging circuit as claimed in claim 1, wherein said pulse density decreases when said charging current is greater than a first predetermined threshold.

9. The charging circuit as claimed in claim 8, wherein said pulse density increases when said charging current is less than a second predetermined threshold that is less than said first predetermined threshold.

10. The charging circuit as claimed in claim 1, wherein said controller controls said pulse density when a battery voltage of a battery pack charged by said charging current is less than a predetermined voltage threshold.

11. The charging circuit as claimed in claim 1, wherein said controller controls said pulse density when a cell voltage for each cell of a plurality of cells charged by said charging current is less than a predetermined voltage threshold.

12. The charging circuit as claimed in claim 1, wherein said charging switch comprises an n-channel metal oxide field effect transistor.

13. A method for charging a battery pack, comprising:

controlling a pulse density of a plurality of pulses; and

adjusting a charging current according to said pulse density.

14. The method as claimed in claim 13, further comprising:

generating said plurality of pulses.

15. The method as claimed in claim 13, further comprising:

controlling a conductance of a charging switch according to said pulse density.

16. The method as claimed in claim 13, further comprising:

monitoring said charging current.

17. The method as claimed in claim 13, further comprising:

monitoring a voltage of said battery pack.

18. The method as claimed in claim 13, further comprising:

decreasing said pulse density when said charging current is greater than a first predetermined threshold.

19. The method as claimed in claim 18, further comprising:

increasing said pulse density when said charging current is less than a second predetermined threshold that is less than said first predetermined threshold.

20. An electronic device comprising:

a charger operable for charging a battery pack;

a charging circuit coupled to said battery pack and said charger for controlling a charging current from said adapter to said battery pack, comprising;

a pulse generator operable for generating a plurality of pulses to control a charging switch coupled between said charger and said battery pack; and

a controller coupled to said pulse generator operable for controlling a pulse density of said plurality of pulses,

wherein a charging current flowing through said charging switch is adjusted according to said pulse density.

21. The electronic device as claimed in claim 20, further comprising a charge pump coupled to said pulse generator operable for receiving said plurality of pulses and for generating a driving signal which controls said charging switch.

22. The electronic device as claimed in claim 20, wherein said pulse density decreases when said charging current is greater than a first predetermined threshold.

23. The charging circuit as claimed in claim 22, wherein said pulse density increases when said charging current is less than a second predetermined threshold that is less than said first predetermined threshold.