System and method of charging a battery using a switching regulator

• US 20070188139A1
• Filed: 02/16/2006
• Published: 08/16/2007
• Est. Priority Date: 02/16/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Summit Microelectronics, Incorporated (Qualcomm, Inc.)
• Inventors: Hussain, M., Adkins, Kenneth, Paparrizos, Georgios
• Granted Patent: US 7,880,445 B2
• Time in Patent Office: Days
• US Class Current: 320/128
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

In one embodiment the present invention includes a system and method of charging a battery using a switching regulator. In one embodiment, a switching regulator receives an input voltage and input current. The output of the switching regulator is coupled to a battery to be charged. The switching regulator provides a current into the battery that is larger than the current into the switching regulator. As the voltage on the battery increases, the current provided by the switching regulator is reduced. The present invention may be implemented using either analog or digital techniques for reducing the current into the battery as the battery voltage increases.

Claims

1. A method of charging a battery comprising:

receiving a first input voltage and a first input current at the input of a switching regulator;

coupling an output of the switching regulator to a terminal of a battery;

generating a first output voltage and a first output current at the terminal of the battery, wherein the switching regulator controls the first output current, and wherein the first output current to the battery is greater than the first input current and the first input voltage is greater than the first output voltage; and

reducing the first output current as the first output voltage on the battery increases.

2. The method of claim 1 further comprising sensing the first output voltage on the battery, and in accordance therewith, adjusting the first output current so that the first input current is below a first value.

3. The method of claim 1 further comprising sensing the first input current to the switching regulator, and in accordance therewith, adjusting the first output current so that the first input current is below a first value.

4. The method of claim 1 further comprising coupling a switching output current and a switching output voltage of the switching regulator through a filter to a terminal of a battery.

5. The method of claim 1 wherein the first output current is reduced across a plurality of current values as the first output voltage on the battery increases.

6. The method of claim 1 wherein the first output current is reduced continuously as the first output voltage on the battery increases.

7. The method of claim 1 wherein the first output current is reduced incrementally as the first output voltage on the battery increases.

8. The method of claim 1 wherein the first output current is reduced continuously to maintain a constant first input current to the switching regulator.

9. The method of claim 1 wherein the first output current is reduced incrementally if the first input current to the switching regulator increases above a threshold.

10. The method of claim 1 further comprising:

sensing the first output voltage on the battery; and

changing a charge parameter in a programmable data storage element from a first value corresponding to a first constant output current to a second value corresponding to a second constant output current if the sensed first output voltage is greater than a first threshold, wherein the first constant output current is greater than the second constant output current.

11. The method of claim 10 further comprising changing the charge parameter across a range of values corresponding to a plurality of successively decreasing constant output currents in response to increases in the sensed first output voltage.

12. The method of claim 1 further comprising:

sensing the first input current to the switching regulator; and

changing a charge parameter in a programmable data storage element from a first value corresponding to a first constant output current to a second value corresponding to a second constant output current if the sensed first input current is greater than a first threshold, wherein the first constant output current is greater than the second constant output current.

13. The method of claim 12 further comprising changing the charge parameter across a range of values corresponding to a plurality of successively decreasing constant output currents in response to the sensed first input current.

14. The method of claim 1 wherein the input of the switching regulator is coupled to a Universal Serial Bus port.

15. The method of claim 1 wherein the output of the switching regulator is coupled to a lithium ion battery, a nickel metal hydride battery, or a nickel cadmium battery.

16. The method of claim 1 wherein the first output current is reduced in accordance with a predefined software algorithm.

17. A method of charging a battery comprising:

receiving a first input voltage and a first input current at the input of a switching regulator;

generating a first controlled output current from the switching regulator into the battery that is greater than the first input current to the switching regulator;

sensing a voltage on the battery or the first input current to the switching regulator; and

reducing the first controlled output current as the voltage on the battery increases.

18. The method of claim 17 wherein the switching regulator operates in a current control mode.

19. The method of claim 17 wherein the voltage on the battery is sensed, and wherein the first controlled output current is reduced continuously in response to sensing an increasing voltage on the battery.

20. The method of claim 17 wherein the voltage on the battery is sensed, and wherein the first controlled output current is incrementally set to lower values in response to sensing an increasing voltage on the battery.

21. The method of claim 17 wherein the first input current is sensed, and wherein the first controlled output current is reduced continuously to maintain a constant first input current to the switching regulator.

22. The method of claim 17 wherein the first input current is sensed, and wherein the first controlled output current is reduced incrementally if the first input current to the switching regulator increases above a threshold.

23. The method of claim 17 further comprising changing a charge parameter in a programmable data storage element from a first value corresponding to a first constant output current to a second value corresponding to a second constant output current, wherein the first constant output current is greater than the second constant output current.

24. The method of claim 17 further comprising changing a charge parameter in a programmable data storage element across a range of values corresponding to successively decreasing constant output currents in response to an increasing voltage on the battery.

25. The method of claim 17 further comprising changing a charge parameter in a programmable data storage element from a first value corresponding to a first constant output current to a second value corresponding to a second constant output current that is less than the first output current if the first input current increases above a threshold.

26. A battery charger comprising:

a switching regulator having a first input, a first output, and a control input, wherein the first input receives a first input voltage and a first input current, and the first output is coupled to a battery to provide a first output voltage and a first output current;

an adjustable current controller having at least one input coupled to sense the first output current, at least one output coupled to a control input of the switching regulator, and a second input coupled to the first input of the switching regulator for detecting changes in the input current or to the battery for detecting changes in the first output voltage, wherein the second input changes the first output current to the battery in response to changes in the first input current or first output voltage,

wherein the switching regulator provides a first output current to the battery that is greater than the first input current, and wherein the first output current is reduced as the voltage on the battery increases.

27. The battery charger of claim 26 further comprising a sense resistor coupled between the first output of the switching regulator and the battery for sensing the first output current, wherein the at least one input of the adjustable current controller comprises a first input coupled to a first terminal of the sense resistor and a second input coupled to a second terminal of the sense resistor.

28. The battery charger of claim 26 wherein the switching regulator operates in a current control mode.

29. The battery charger of claim 26 wherein the first output current is adjusted so that the first input current remains below a first value.

30. The battery charger of claim 26 further comprising a sense circuit that senses the first input current, wherein the second input of the adjustable current controller is coupled to the sense circuit for detecting changes in the input current.

31. The battery charger of claim 30 wherein the sense circuit comprises a first resistor coupled to the input of the switching regulator.

32. The battery charger of claim 30 further comprising an analog or digital controller coupled between the sense circuit and the adjustable current controller, wherein the analog or digital controller changes a control voltage at the second input of the adjustable current controller if the first input current increases above a first threshold.

33. The battery charger of claim 32 wherein the controller is a digital controller, and wherein the digital controller changes digital bits in at least one programmable storage element if the first input current increases above a first threshold.

34. The battery charger of claim 32 wherein the controller is an analog controller, and wherein the analog controller has at least one input coupled to the sense circuit and at least one output coupled to the adjustable current controller, and where the analog controller changes a voltage at the second input of the adjustable current controller if the first input current increases above a first threshold.

35. The battery charger of claim 26 wherein a second input of the adjustable current controller is coupled to the battery for detecting changes in the first output voltage.

36. The battery charger of claim 35 further comprising a digital controller having at least one input coupled to the battery and an output coupled to the second input of the adjustable current controller, wherein the digital controller changes digital bits in at least one programmable data storage element if the first output voltage increases above a first threshold, and in accordance therewith, changes a voltage at the second input of the adjustable current controller for reducing the first output current.

37. The battery charger of claim 36 further comprising an analog-to-digital converter coupled between the battery and the at least one input of the digital controller, and a digital-to-analog converter coupled between the programmable data storage element and the second input of the adjustable current controller.

38. The battery charger of claim 36 wherein the programmable data storage element is a register.

39. The battery charger of claim 36 wherein the programmable data storage element is a register, and wherein the digital controller changes digital bits in the register by loading digital bits into the register from a volatile memory.

40. The battery charger of claim 36 wherein the programmable data storage element is a register, and wherein the digital controller changes digital bits in the register by loading digital bits into the register from a nonvolatile memory.

41. The battery charger of claim 26 wherein the switching regulator further comprises a switching transistor, an error amplifier, and switching circuit, and wherein the at least one output of the adjustable current controller is coupled to a control terminal of the switching transistor through the error amplifier and switching circuit.

42. The battery charger of claim 26 wherein the switching regulator comprises a pulse width modulation circuit.

43. The battery charger of claim 26 wherein the adjustable current controller generates a first control signal to the switching regulator to produce a constant first output current into the battery, and wherein the adjustable current controller changes the first control signal to continuously reduce the constant first output current as the voltage on the battery increases.

44. The battery charger of claim 26 wherein the adjustable current controller generates a first control signal to the switching regulator to produce a constant first output current into the battery, and wherein at least one data storage element coupled to the adjustable current controller is reprogrammed by a controller in response to an increase in the first input current or first output voltage, and in accordance therewith, the adjustable current controller changes the first control signal to incrementally reduce the constant first output current.

45. The battery charger of claim 26 further comprising a register coupled to the second input of the adjustable current controller, wherein digital bits in the register are changed, in response to an increase in the first input current or first output voltage, from a first value to a second value, and in accordance therewith, the first output current is reduced.

46. A method of charging a battery comprising:

receiving a first voltage and a first current at a first terminal of a switching transistor, wherein the first voltage and first current are coupled to the first terminal of the switching transistor from a power source;

receiving a switching signal at a control input of the switching transistor, and in accordance therewith, generating a second voltage and a second current at a second terminal of the switching transistor;

filtering the second voltage and second current to produce a filtered voltage and filtered current;

coupling the filtered voltage and filtered current to a terminal of a battery, wherein the filtered voltage at the terminal of the battery is less than the first voltage at the first terminal of the switching transistor, and wherein the filtered current into the terminal of the battery is greater than the first current into the first terminal of the switching transistor; and

reducing the filtered current across a range of current values that are greater than a value of the first current as the voltage on the battery increases across a corresponding range of values that are less than the first voltage.

47. The method of claim 46 wherein filtering comprises coupling the second current to the battery terminal through at least one inductor.

48. The method of claim 46 wherein the filtered current is adjusted so that the first current remains below a first value.

49. The method of claim 46 further comprising sensing the filtered current and the voltage on the battery, and in accordance therewith, controlling the filtered current.

50. The method of claim 46 further comprising sensing the first current and the filtered current, and in accordance therewith, controlling the filtered current.

51. The method of claim 46 wherein the power source is a Universal Serial Bus port.

52. A battery charger comprising:

a switching regulator including at least one switching transistor, the switching transistor having a first input to receive a first input voltage and a first input current, and a first output coupled to a battery to provide a first output voltage and a first output current;

a current controller for controlling the first output current to the battery, the current controller having at least one input for sensing the first output current to the battery, a second input for adjusting the first output current in response to a control signal, and a first output coupled to the switching regulator; and

a controller having a first input coupled to the first input of the switching regulator or the battery, and at least one output coupled to the second input of the current controller, wherein the controller is responsive to increases in the first input current or first output voltage, and wherein the controller changes the control signal at the second input of the current controller to reduce the first output current if the first input current or first output voltage increase,

wherein the switching regulator provides a first output current to the battery that is greater than the first input current, and wherein the first output current is reduced as the first output voltage on the battery increases.

53. The battery charger of claim 52 further comprising an output sense resistor coupled to the first output of the switching transistor for sensing the first output current, and wherein the current controller is coupled to first and second terminals of the output sense resistor for controlling the first output current.

54. The battery charger of claim 52 further comprising an input sense resistor coupled to the first input of the switching transistor for sensing the first input current, and wherein the controller is coupled to first and second terminals of the input sense resistor.

55. The battery charger of claim 54 wherein the controller comprises an analog controller, wherein the analog controller generates a control voltage at the second input of the current controller for reducing the first output current in response to the first input current.

56. The battery charger of claim 54 wherein the controller comprises a digital controller, the circuit further comprising:

an analog-to-digital converter having inputs coupled across the input sense resistor and an output coupled to the digital controller;

a register coupled to the digital controller; and

a digital-to-analog converter having an input coupled to the register and an output coupled to the second input of the current controller,

wherein the digital controller reprograms the register in response to an increase in the first input current, and in accordance therewith, the first output current is reduced.

57. The battery charger of claim 56 further comprising a nonvolatile memory, wherein the digital controller reprograms the register with parameters stored in the nonvolatile memory.

58. The battery charger of claim 56 further comprising a volatile memory, wherein the digital controller reprograms the register with parameters stored in the volatile memory.

59. The battery charger of claim 52 wherein the first input of the controller is coupled to the battery.

60. The battery charger of claim 59 wherein the controller comprises an analog controller, wherein the analog controller generates a control voltage at the second input of the current controller for reducing the first output current in response to the first output voltage.

61. The battery charger of claim 59 wherein the controller comprises a digital controller, the circuit further comprising:

an analog-to-digital converter having an input coupled to the battery and an output coupled to the digital controller;

a register coupled to the digital controller; and

a digital-to-analog converter having an input coupled to the register and an output coupled to the second input of the current controller,

wherein the digital controller reprograms the register in response to an increase in the first output voltage, and in accordance therewith, the first output current is reduced.

62. The battery charger of claim 61 further comprising a nonvolatile memory, wherein the digital controller reprograms the register with parameters stored in the nonvolatile memory.

63. The battery charger of claim 61 further comprising a volatile memory, wherein the digital controller reprograms the register with parameters stored in the volatile memory.

64. The battery charger of claim 52 wherein the controller and current controller are on the same integrated circuit.

65. The battery charger of claim 52 wherein the controller and current controller are on different integrated circuits.

66. A battery charger comprising:

a switching regulator including at least one switching transistor, the switching transistor having a first input to receive a first input voltage and a first input current, and a first output coupled to a battery to provide a first output voltage and a first output current;

current controller means, coupled to the switching regulator, for sensing and controlling the output current to the battery and for changing the first output current to the battery in response to a control signal, and

controller means for generating the control signal to the current controller means in response to the first input current or first output voltage;

wherein the switching regulator provides a first output current to the battery that is greater than the first input current, and wherein the first output current is adjusted as the voltage on the battery increases.

67. The battery charger of claim 66 further comprising sense circuit means for sensing the first input current.

68. The battery charger of claim 66 further comprising sense circuit means for sensing the first output current.

69. The battery charger of claim 66 wherein the controller means comprises an analog circuit.

70. The battery charger of claim 66 wherein the controller means comprises a digital circuit.

71. The battery charger of claim 66 wherein the current controller means comprises first and second inputs for receiving voltages corresponding to the first output current, and a second input for receiving the control signal to reduce the first output current as the voltage on the battery increases.

72. The battery charger of claim 66 further comprising voltage control means for controlling the first output voltage.

73. The battery charger of claim 66 wherein the switching regulator further comprises switching circuit means for providing a switching signal to a control terminal of the switching transistor.