Systems and methods of programming voltage and current in a battery charger

• US 7,528,574 B1
• Filed: 02/16/2006
• Issued: 05/05/2009
• Est. Priority Date: 02/16/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Summit Microelectronics, Incorporated (Qualcomm, Inc.)
• Inventors: Hussain, M Abid, Adkins, Kenneth C
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US11/357,259
• Time in Patent Office: 1,174 Days
• Field of Search: 320/106, 320/114, 320/115, 320/128, 320/132, 320/161
• US Class Current: 320/128
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/446 Initial charging measures
• CPC Class Codes: H01M 10/448 End of discharge regulating measures
• 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 method of charging a battery comprising storing a plurality of charging parameters in one or more programmable data storage elements. The charging parameters may be used to program a variety of battery charging parameters including constant currents, voltages, thresholds, timers, or temperature controls. In one embodiment, the present invention includes a software algorithm that changes the charging parameters to improve battery charging efficiency.

Claims

1. A method of charging a battery comprising:

storing a plurality of charging parameters in one or more programmable data storage elements;

supplying a constant current to said battery during a first time period, wherein the constant current supplied is set by a first parameter of said stored charging parameters and the first parameter is variable across a range of values to program the constant current across a corresponding range of current values; and

generating a constant voltage to said battery during a second time period following the first time period if a voltage on the battery is above a first threshold, wherein the constant voltage is set by a second parameter of said stored charging parameters and the second parameter is variable across a range of values to program the constant voltage across a corresponding range of voltage values.

2. The method of claim 1 wherein said range of second charging parameter values includes at least a highest value, a lowest value, and a plurality of intermediate values between the highest and lowest values, and wherein said constant voltage is programmed to the highest value, the lowest value, or any intermediate value by the second charging parameter in one of the programmable data storage elements.

3. The method of claim 1 wherein said range of first charging parameter values includes at least a highest value, a lowest value, and a plurality of intermediate values between the highest and lowest values, and wherein said constant current is programmed to the highest value, the lowest value, or any intermediate value by the first charging parameter in one of the programmable data storage elements.

4. The method of claim 1 wherein supplying a constant current comprises:

supplying a first constant precharge current to said battery if a voltage on said battery is below a second threshold; and

supplying a second constant current to said battery if a voltage on said battery is above the second threshold, wherein the first constant precharge current and the second constant current are set by parameters stored in at least one of the programmable data storage elements.

5. The method of claim 4 wherein the second threshold is set by a parameter stored in at least one of the programmable data storage elements.

6. The method of claim 1 further comprising reprogramming one or more of the charging parameters stored in the data storage elements.

7. The method of claim 6 wherein the charging parameters are reprogrammed while the battery is charging.

8. The method of claim 6 wherein the constant current is reprogrammed to a plurality of different values during the first time period.

9. The method of claim 6 wherein the one or more charging parameters are reprogrammed in accordance with a predefined software algorithm.

10. The method of claim 9 wherein the algorithm changes one or more charging parameters while the battery is charging.

11. The method of claim 9 wherein the algorithm changes one or more charging parameters over multiple charging cycles.

12. The method of claim 9 wherein the algorithm changes the constant current based on a sensed battery voltage or current.

13. The method of claim 9 wherein the algorithm is executed on a processor and the processor reprograms one or more of the data storage elements, and in accordance therewith, changes a corresponding one or more charging parameters.

14. The method of claim 9 wherein the algorithm is stored in nonvolatile memory.

15. The method of claim 1 wherein the data storage element is a volatile storage device.

16. The method of claim 1 wherein the data storage element is a nonvolatile storage device.

17. The method of claim 16 wherein the plurality of charging parameters are stored in the nonvolatile storage device and transferred to a volatile storage device.

18. The method of claim 1 wherein the battery is charged using a linear regulator.

19. The method of claim 1 wherein the battery is charged using a switching regulator.

20. The method of claim 19 wherein the switching regulator switches at a first frequency, and wherein the first frequency is set by a parameter stored in one of the programmable data storage elements.

21. The method of claim 4 further comprising measuring a time the first constant precharge current is supplied to the battery and terminating the first constant precharge current if a voltage on said battery is below the second threshold after a predetermined time period, wherein the predetermined time period is set by a parameter stored in one of the programmable data storage elements.

22. The method of claim 4 further comprising measuring a time the second constant current is supplied to the battery and terminating the second constant current if a voltage on said battery is below the first threshold after a predetermined time period, wherein the predetermined time period is set by a parameter stored in one of the programmable data storage elements.

23. The method of claim 1 further comprising third and fourth stored parameters, wherein the third parameter is used to program an over-temperature limit and the fourth parameter is used to program an under-temperature limit, and wherein if the temperature of the battery is above the over-temperature limit or below the under-temperature limit, then charging is suspended.

24. The method of claim 23 further comprising a fifth stored parameter, wherein the fifth parameter is used to program a bias current into a battery temperature sensor.

25. The method of claim 1 wherein the constant current comprises a first constant precharge current, and the first constant precharge current is set by a first charging parameter stored as a plurality of digital bits.

26. The method of claim 25 wherein the constant current further comprises a second constant current greater then the first constant precharge current, and the second constant current is set by a second charging parameters stored as a plurality of digital bits.

27. The method of claim 26 further comprising a second threshold for selecting between the first constant precharge current and the second constant current, wherein the second threshold is set by a third charging parameter stored as a plurality of digital bits.

28. The method of claim 1 wherein the second parameter corresponding to the constant voltage is stored as a plurality of digital bits.

29. The method of claim 1 wherein the plurality of charging parameters are each stored as a plurality digital bits, and each charging parameter is separately programmable.

30. The method of claim 29 wherein the digital bits corresponding to the plurality of charging parameters are converted to an analog parameter.

31. The method of claim 30 wherein the analog parameter is an analog voltage or current.

32. The method of claim 29 wherein the digital bits are converted to an analog parameter using a digital-to-analog converter.

33. The method of claim 1 wherein the data storage elements are programmed using a digital bus.

34. The method of claim 33 wherein the digital bus comprises a serial bus.

35. The method of claim 33 wherein the digital bus comprises a parallel bus.

36. The method of claim 33 wherein said battery comprises a lithium ion battery, a nickel metal hydride battery or a nickel cadmium battery.

37. The method of claim 1 wherein the charging parameters change a constant precharge current, a precharge threshold, a constant charge current greater than the constant precharge current, a float voltage, a constant current-to-constant voltage threshold, a termination current threshold, a precharge timeout, a fast charge timeout, an over-temperature limit, an under-temperature limit, a negative temperature coefficient thermistor bias current, or a switching regulator frequency across a range of values.

38. A programmable battery charger comprising:

a regulator having a first input to receive a first power source, a first output to provide a regulated output to at least one battery, and a control input;

a constant current controller having a first input coupled to a first programmable data storage element, a feedback input coupled to at least one current sense input, and an output coupled to the control input of the regulator, wherein the first programmable data storage element configures the constant current controller to supply a first programmed constant current to said battery if a voltage on said battery is below a first threshold; and

a constant voltage controller having a first input coupled to a second programmable data storage element, a second input coupled to at least one voltage sense input, and an output coupled to the control input of the regulator, wherein the second programmable data storage element configures the constant voltage controller to generate a first programmed constant voltage to said battery if the voltage on said battery is above the first threshold, wherein the programmed constant voltage is variable across a range of values.

39. The battery charger of claim 38 wherein said range of voltage values includes at least a highest value, a lowest value, and a plurality of intermediate values between the highest and lowest values, and wherein said constant voltage is programmed to the highest value, the lowest value, or any intermediate value by the second programmable data storage element.

40. The battery charger of claim 38 further comprising a third programmable data storage element coupled to the constant current controller, wherein the third data storage element configures the constant current controller to supply a second programmed precharge current to said battery if a voltage on said battery is below second precharge threshold, and wherein the precharge current is less than the first programmed constant current.

41. The battery charger of claim 40 further comprising a fourth programmable data storage element coupled to the constant current controller, wherein the fourth programmable data storage element sets the second precharge threshold.

42. The battery charger of claim 41 further comprising a multiplexer having a first input coupled to the first programmable data storage element, a second input coupled to the third programmable data storage element, a control input coupled to the fourth programmable data storage element, and an output coupled to the constant current controller.

43. The battery charger of claim 42 further comprising a comparator having a first input coupled to a reference voltage, a second input coupled to the fourth programmable data storage element, and an output coupled to the control input of the multiplexer.

44. The battery charger of claim 38 further comprising a digital-to-analog converter having a first input coupled to the first programmable data storage element and an analog output coupled to the constant current controller.

45. The battery charger of claim 40 further comprising a digital-to-analog converter having a first input coupled to the first programmable data storage element or the third programmable data storage element, and an analog output coupled to the constant current controller.

46. The battery charger of claim 38 further comprising a digital-to-analog converter having a first input coupled to the second programmable data storage element and an analog output coupled to the constant voltage controller.

47. The battery charger of claim 38 further comprising a third programmable data storage element coupled to a shutdown circuit, wherein the third programmable data storage element is used to terminate battery charging if a current into said battery is below a programmed termination current threshold.

48. The battery charger of claim 47 further comprising a digital-to-analog converter having a first input coupled to the third programmable data storage element and an analog output coupled to the shutdown circuit.

49. The battery charger of claim 47 further comprising a comparator having a first input coupled to at least one current sense terminal, a second input coupled to the third programmable data storage element, and an output coupled to the shutdown circuit.

50. The battery charger of claim 38 further comprising a third programmable data storage element and a fourth programmable data storage element, wherein the third programmable data storage element is used to program an over-temperature limit and the fourth programmable data storage element is used to program an under-temperature limit, and wherein if the temperature of the battery is above the over-temperature limit or below the under-temperature limit, then charging is suspended.

51. The battery charger of claim 50 further comprising a fifth programmable data storage element, wherein the fifth programmable data storage element is used to program a bias current into a battery temperature sensor.

52. The battery charger of claim 38 further comprising a third programmable data storage element, wherein the regulator is a switching regulator, and wherein the third programmable data storage element is used to program the switching frequency of the switching regulator.

53. The battery charger of claim 38 wherein a plurality of programmable data storage elements store a corresponding plurality of charging parameters, wherein the charging parameters change a constant precharge current, a precharge threshold, a constant charge current greater than the constant precharge current, a float voltage, a constant current-to-constant voltage threshold, a termination current threshold, a precharge timeout, a fast charge timeout, an over-temperature limit, an under-temperature limit, a negative temperature coefficient thermistor bias current, or a switching regulator frequency across a range of values.

54. The battery charger of claim 38 further comprising a controller coupled to the first and second programmable data storage elements to reprogram the first and second programmable data storage elements.

55. The battery charger of claim 38 further comprising a system processor coupled to the first and second programmable data storage elements, wherein the system processor includes a software algorithm for controlling reprogramming of the first and second programmable data storage elements.