POWER SUPPLY CIRCUIT AND METHOD FOR PROVIDING OUTPUT VOLTAGE

• US 20100066311A1
• Filed: 09/15/2008
• Published: 03/18/2010
• Est. Priority Date: 09/15/2008
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: Bognar, Frank, Bao, Cheng, Guthrie, Martin
• Granted Patent: US 8,519,671 B2
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

Various embodiments are described herein for a charging device and an associated charging method for charging a rechargeable battery. The charging device generally includes a current source that is coupled to a power source and configured to provide a charging current to the rechargeable battery. The charging device further includes a controller that is configured to control the current source to provide the charging current with an amplitude that is less than the charging current required by the rechargeable battery in a given charging state to bring an output voltage of the current source towards the voltage of the rechargeable battery.

Claims

1. A charging device for charging a rechargeable battery, wherein the charging device comprises:

a current source coupled to a power source and configured to provide a charging current to the rechargeable battery; and

a controller configured to control the current source to provide the charging current with an amplitude that is less than the charging current required by the rechargeable battery in a given charging state to bring an output voltage of the current source towards the voltage of the rechargeable battery.

2. The charging device of claim 1, wherein the current source is coupled to a battery interface of the rechargeable battery and the controller is configured to vary the amplitude of the charging current provided by the current source, the variation comprising first and second amplitudes, the second amplitude being smaller than the first amplitude, and the controller is configured to measure an output voltage at an output node of the current source to determine whether the charging state of the rechargeable battery is a constant voltage charging state.

3. The charging device of claim 2, wherein the controller is configured to set the current source to provide the charging current at the second amplitude, compare the output voltage with a voltage threshold and determine that the charging state of the rechargeable battery is the constant voltage charging state when the output voltage is above the voltage threshold and to set the current source to operate in a sleep mode to stop charging the rechargeable battery when the charging state is the constant voltage charging state.

4. The charging device of claim 2, wherein the controller is configured to set the current source to provide the charging current at the first amplitude, compare the output voltage with a voltage threshold and allow the charging of the rechargeable battery when the output voltage is below the voltage threshold.

5. The charging device of claim 4, wherein if the comparison indicates that the output voltage is above the voltage threshold, the controller is configured to then set the current source to provide the charging current with the second amplitude and if the output voltage then goes below the voltage threshold the charging state of the rechargeable battery is a preliminary charging state and the controller is configured to allow the current source to continue providing the charging current to charge the rechargeable battery.

6. The charging device of claim 2, wherein the first amplitude is between current amplitudes associated with a pre-charge current setting and a fast-charge current setting and the second amplitude is below the pre-charge current setting.

7. The charging device of claim 3, wherein the voltage threshold is between a minimum charging device voltage and a charging device regulation voltage.

8. The charging device of claim 1, wherein the current source comprises a buck-boost DC-DC switched converter.

9. The charging device of claim 1, wherein the battery does not have a battery interface and prior to charging the controller is configured to measure an output voltage at an output node of the current source, allow charging if the measured output voltage is lower than a first voltage threshold or not allow charging if the measured output voltage is higher than the first voltage threshold.

10. The charging device of claim 9, wherein if charging is allowed the controller configures the current source to provide the charging current at a first amplitude if the measured output voltage is greater than a second voltage threshold and at a second amplitude if the measured output voltage is less than the second voltage threshold.

11. The charging device of claim 10, wherein the controller is configured to subsequently measure the output voltage and if the subsequently measured output voltage is greater than the first voltage threshold, the controller is configured to disable the current source if battery capacity is near full or configure the current source to provide the charging current at the second amplitude, indicate the battery capacity is near full and perform an additional output voltage measurement if the battery capacity is not near full.

12. The charging device of claim 11, wherein if the subsequently measured output voltage is less than the first voltage threshold and less than the second voltage threshold the controller is configured to set the current source to provide the charging current at the second amplitude, and perform the additional output voltage measurement.

13. The charging device of claim 11, wherein if the subsequently measured output voltage is less than the first voltage threshold and greater than the second voltage threshold, the controller is configured to set the current source to provide the charging current at the second amplitude and perform the additional output voltage measurement if the battery capacity is near full or the controller is configured to set the current source to provide the charging current at the first amplitude and perform the additional output voltage measurement if the battery capacity is not near full.

14. The charging device of claim 10, wherein the first voltage threshold is a regulation voltage setting, the second voltage threshold is a pre-charge voltage setting, the first amplitude is between current amplitudes associated with a pre-charge current setting and a fast-charge current setting and the second amplitude is below a max pre-charge current setting allowed with the rechargeable battery.

15. The charging device of claim 1, wherein the current source is coupled to a battery interface of the rechargeable battery and the controller is configured to vary the amplitude of an output voltage at an output node of the current source, the variation comprising first and second amplitudes, the second amplitude being smaller than the first amplitude, and the controller is configured to measure an amplitude of the charging current to determine whether the charging state of the rechargeable battery is a constant voltage charging state.

16. The charging device of claim 15, wherein the controller is configured to set the output voltage with the second amplitude, and if there is a substantial reduction in amplitude of the charging current the controller determines that the charging state of the rechargeable battery is the constant voltage charging state and sets the current source to operate in a sleep mode to stop charging the rechargeable battery.

17. The charging device of claim 15, wherein the controller is configured to set the output voltage at the first amplitude, compare the amplitude of the charging current with a current threshold and allow the charging of the rechargeable battery when the amplitude of the charging current is above the current threshold.

18. The charging device of claim 17, wherein if the comparison indicates that the amplitude of the charging current is below the current threshold, the controller is configured to then set the output voltage at the second amplitude and if the charging current stays substantially similar in amplitude the charging state of the rechargeable battery is a preliminary charging state and the controller is configured to continue charging the rechargeable battery.

19. The charging device of claim 15, wherein the first amplitude of the output voltage is set to be greater than the minimum charging device voltage and the second amplitude of the output voltage is set to be greater than the pre-charge voltage setting but less than the minimum charging device voltage.

20. A method for charging a rechargeable battery, wherein the method comprises:

determining a charging state of the rechargeable battery;

configuring a current source to provide a charging current with an amplitude that is less than the charging current required by the rechargeable battery in the determined charging state; and

providing the charging current from the current source to the rechargeable battery at the lower amplitude to bring an output voltage of the current source towards the voltage of the rechargeable battery.

21. The method of claim 20, wherein the method further comprises providing the charging current from the current source to a battery interface of the rechargeable battery, varying the amplitude of the charging current provided by the current source, the variation comprising first and second amplitudes, the second amplitude being smaller than the first amplitude, and measuring an output voltage at an output node of the current source to determine whether the charging state of the rechargeable battery is a constant voltage charging state.

22. The method of claim 21, wherein the method further comprises setting the current source to provide the charging current with the second amplitude, comparing the output voltage with a voltage threshold and determining that the charging state of the rechargeable battery is the constant voltage charging state when the output voltage is above the voltage threshold, and setting the current source to operate in a sleep mode to stop charging the rechargeable battery when the charging state is the constant voltage charging state.

23. The method of claim 21, wherein the method further comprises setting the current source to provide the charging current with the first amplitude, comparing the output voltage with a voltage threshold and allowing the charging of the rechargeable battery when the output voltage is below the voltage threshold.

24. The method of claim 23, wherein if the comparison indicates that the output voltage is above the voltage threshold, the method further comprises setting the current source to provide the charging current with the second amplitude and if the output voltage then goes below the voltage threshold the charging state of the rechargeable battery is a preliminary charging state and the method further comprises continuing to provide the charging current to charge the rechargeable battery.

25. The method of claim 22, wherein the method further comprises setting the first amplitude between current amplitudes associated with a pre-charge current setting and a fast-charge current setting and setting the second amplitude below the pre-charge current setting.

26. The method of claim 22, wherein the method further comprises setting the voltage threshold between a minimum charging device voltage and a charging device regulation voltage.

27. The method of claim 20, wherein the battery does not have a battery interface and prior to charging the method comprises measuring an output voltage at an output node of the current source, allowing charging if the measured output voltage is lower than a first voltage threshold or not allowing charging if the measured output voltage is higher than the first voltage threshold.

28. The method of claim 27, wherein if charging is allowed the method comprises setting the current source to provide the charging current at a first amplitude if the measured output voltage is greater than a second voltage threshold and at a second amplitude if the measured output voltage is less than the second voltage threshold.

29. The method of claim 28, wherein the method further comprises subsequently measuring the output voltage and if the subsequently measured output voltage is greater than the first voltage threshold the method comprises disabling the current source if battery capacity is near full or setting the current source to provide the charging current at the second amplitude, indicating the battery capacity is near full and performing an additional output voltage measurement if the battery capacity is not near full.

30. The method of claim 29, wherein if the subsequently measured output voltage is less than the first voltage threshold and less than the second voltage threshold the method further comprises setting the current source to provide the charging current at the second amplitude and performing the additional output voltage measurement.

31. The method of claim 29, wherein if the subsequently measured output voltage is less than the first voltage threshold and greater than the second voltage threshold, the method further comprises setting the current source to provide the charging current at the second amplitude and performing the additional output voltage measurement if the battery capacity is near full or setting the current source to provide the charging current at the first amplitude and performing the additional output voltage measurement if the battery capacity is not near full.

32. The method of claim 28, wherein the method comprises setting the first voltage threshold to a regulation voltage setting, setting the second voltage threshold to a pre-charge voltage setting, setting the first amplitude between current amplitudes associated with a pre-charge current setting and a fast-charge current setting and setting the second amplitude below a max pre-charge current allowed with the rechargeable battery.

33. The method of claim 20, wherein the method further comprises providing the charging current from the current source to a battery interface of the rechargeable battery, varying the amplitude of an output voltage at an output node of the current source, the variation comprising first and second amplitudes, the second amplitude being smaller than the first amplitude, and measuring an amplitude of the charging current to determine whether the charging state of the rechargeable battery is a constant voltage charging state.

34. The method of claim 33, wherein the method further comprises setting the output voltage at the second amplitude, and if there is a substantial reduction in amplitude of the charging current the method comprises determining that the charging state of the rechargeable battery is the constant voltage charging state and setting the current source to operate in a sleep mode to stop charging the rechargeable battery.

35. The method of claim 33, wherein the method further comprises setting the output voltage at the first amplitude, comparing the amplitude of the charging current with a current threshold and allowing the charging of the rechargeable battery when the amplitude of the charging current is above the current threshold.

36. The method of claim 35, wherein if the comparison indicates that the amplitude of the charging current is below the current threshold, the method further comprises setting the output voltage at the second amplitude and if the amplitude of the charging current stays substantially similarly the charging state of the rechargeable battery is a preliminary charging state and the method comprises continuing to charge the rechargeable battery.

37. The method of claim 33, wherein the method comprises setting the first amplitude of the output voltage to be greater than the minimum charging device voltage and setting the second amplitude of the output voltage to be greater than the pre-charge voltage setting but less than the minimum charging device voltage.

38. A computer program product comprising a computer readable medium embodying program code means executable by a processor of a charging device for executing a method of charging a rechargeable battery, wherein, the method comprises the steps of claim 20.