Switching battery charging systems and methods

• US 7,834,591 B2
• Filed: 02/16/2006
• Issued: 11/16/2010
• Est. Priority Date: 02/16/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Summit Microelectronics, Incorporated (Qualcomm, Inc.)
• Inventors: Hussain, M Abid, Paparrizos, Georgios Konstantinos, Adkins, Kenneth C
• Primary Examiner(s): Vu; Bao Q
• Assistant Examiner(s): Tran; Nguyen
• Application Number:
  US11/356,594
• Publication Number:
  US 20070188134A1
• Time in Patent Office: 1,734 Days
• Field of Search: 320/114, 320/124, 320/28, 320/132, 320/137, 320/143, 320/151, 320/152
• US Class Current: 320/137
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 2207/30 Charge provided using DC bus or data bus of a computer
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Embodiments of the present invention include techniques for charging a battery using a switching regulator. Some embodiments include programmable switching battery chargers that can be configured using digital techniques. Other embodiments include switching battery chargers that modify the battery current based on sensed circuit conditions such as battery voltage or input current to the switching regulator. In one embodiment, the present invention includes a USB battery charger.

Claims

1. A Universal Serial Bus (USB) battery charger comprising:

a switching regulator having at least one switching transistor, the switching transistor having a first input and a first output, wherein the first input of the switching transistor is coupled to a USB power source; and

a filter having a first input and a first output, wherein the first input of the filter is coupled to the first output of the switching transistor;

wherein the switching regulator is configured to receive a USB voltage, and generate a switching signal to a control terminal of the switching transistor, and wherein a switching current and a switching voltage at the output of the switching transistor are coupled through the filter to a battery to generate a filtered current and a filtered voltage to charge the battery, wherein the battery is coupled to the first output of the filter,

wherein the filtered current is greater than a first input current into the first input of the switching transistor, and the filtered current is reduced, in a current control mode, as a voltage on the battery increases.

2. The battery charger of claim 1 wherein the filtered voltage is sensed by a voltage controller to control the switching signal at the control terminal of the switching transistor.

3. The battery charger of claim 2 wherein the voltage controller includes a first input coupled to a programmable data storage element, a second input coupled to sense voltage, and an output coupled to the control input of the switching transistor, wherein the programmable data storage element configures the voltage controller to generate a programmed voltage to said battery if the voltage on said battery is above the first threshold.

4. The battery charger of claim 1 wherein the filtered current is sensed by a current controller to control the switching signal at the control terminal of the switching transistor.

5. The battery charger of claim 4 wherein the current controller includes a first input coupled to a programmable data storage element, a second input coupled to sense current, and an output coupled to the control input of the switching transistor, and wherein the programmable data storage element configures the current controller to supply a first programmed current to said battery if the voltage on said battery is below a first threshold.

6. The battery charger of claim 4 wherein the current controller receives an input signal indicating a maximum input current, the input signal programming the current controller to set a maximum battery current based on the maximum input current.

7. The battery charger of claim 1 wherein the USB voltage is in a range of at least 4.1 volts to 5.25 volts.

13. The battery charger of claim 1 wherein the switching regulator includes a control input, and wherein the first output of the filter is coupled to the battery through a first resistor, the battery charger further comprising:

a current controller having first and second current sense inputs coupled to first and second terminals of the first resistor for sensing the filtered current, and a control output coupled to the control input of the switching regulator; and

a voltage controller having a first voltage sense input coupled to the battery for sensing the voltage on the battery, and a control output coupled to the control input of the switching regulator.

14. The battery charger of claim 13 wherein the current controller includes a control input for setting the filtered current, and wherein a first logic signal corresponding to a maximum USB current is coupled to the control input of the current controller to set the filtered current.

15. The battery charger of claim 1 further comprising a current controller to set the filtered current to be greater than the first input current received at the first input of the switching transistor.

16. The battery charger of claim 1 further comprising a current controller, wherein a control input of the current controller is coupled to the first input of the switching transistor, and the current controller reduces the filtered current in response to a control signal received at the control input as the voltage on the battery increases.

17. The battery charger of claim 13 further comprising:

a first programmable data storage element coupled to a control input of the current controller for setting the filtered current, wherein the first programmable data storage element configures the current controller to supply a first programmed current to said battery if the voltage on said battery is below a first threshold; and

a second programmable data storage element coupled to a control input of the voltage controller for setting the first output voltage, wherein the second programmable data storage element configures the voltage controller to generate a programmed constant voltage to said battery if the voltage on said battery is above the first threshold.

18. The battery charger of claim 1 further comprising a current controller, wherein a control input of the current controller is coupled to the battery, and the current controller reduces the filtered current in response to a control signal received at the control input as the voltage on the battery increases.

19. The battery charger of claim 1 wherein the first input current is maintained approximately constant as the filtered current is reduced.

20. The battery charger of claim 19 wherein the first input current is below a threshold.

21. The battery charger of claim 1 wherein the filtered current is reduced before a transition from said current control mode to a voltage control mode.

22. The battery charger of claim 21 wherein the filtered current is reduced after a precharge period.

23. The battery charger of claim 1 wherein the filtered current is set at a value above a maximum current capability of the USB power source and reduced under control of a current controller circuit.

24. The battery charger of claim 1 wherein the filtered current is greater than a maximum current capability of the USB power source.

8. A method of charging a battery from a Universal Serial Bus (USB) port comprising:

receiving a first input voltage and a first input current at an input of a switching regulator from a USB power source;

coupling a switching output voltage and current from the switching regulator through a filter to a terminal of a battery; and

generating a first output voltage and a first output current at the terminal of the battery;

wherein the first input voltage is greater than the first output voltage on the battery, the first output current to the battery is greater than the first input current, and wherein the first output current is reduced, in a current control mode, as the first output voltage on the battery increases.

9. The method of claim 8 further comprising receiving a logic signal corresponding to a USB port type, wherein the first output current is greater than 100 mA and the first input current is below 100 mA when the logic signal is in a first state, and the first output current is greater than 500 mA and the first input current is below 500 mA when the logic signal is in a second state.

10. The method of claim 8 further comprising storing a charging parameter in a programmable data storage element, wherein the first output current is set by said charging parameter.

11. The method of claim 8 wherein the switching regulator senses the first output voltage and generates a switching signal to control the first output voltage.

12. The method of claim 11 further comprising storing a charging parameter in a programmable data storage element, wherein the first output voltage is set by said charging parameter.

25. The method of claim 8 wherein the first input current is maintained approximately constant as the first output current is reduced.

26. The method of claim 25 wherein the first input current is below a threshold.

27. The method of claim 25 further comprising sensing the first input current and controlling the first output current to reduce based on the first input current.

28. The method of claim 8 wherein the first output current is reduced before a transition from said current control mode to a voltage control mode.

29. The method of claim 28 wherein the first output current is reduced after a precharge period.

30. The method of claim 8 wherein the first output current is set at a value above a maximum current capability of the USB power source and reduced under control of a current controller circuit.

31. The method of claim 8 wherein the first output current is greater than a maximum current capability of the USB power source.

32. A circuit comprising:

a switching regulator having a first input to receive an input voltage and an input current from a USB power source and a first output coupled to a battery;

a current controller coupled to the switching regulator; and

a voltage controller coupled to the switching regulator,

wherein the current controller and switching regulator operate in a current control mode to generate an output current to the battery, and wherein the voltage controller and switching regulator operate in a voltage control mode to generate an output voltage to the battery, and

wherein, during at least a of portion of the current control mode, the input voltage is greater than the output voltage on the battery, the output current to the battery is greater than the input current to the switching regulator, and the current controller reduces the output current to the battery as the voltage on the battery increases.

33. The circuit of claim 32 further comprising an input sense circuit to sense the input current from the USB power source, wherein an input of the current controller is coupled to the input sense circuit to reduce the output current to the battery as the voltage on the battery increases.

34. The circuit of claim 33 wherein the input sense circuit comprises a resistor between the first input of the switching regulator and an output of the USB power source.

35. The circuit of claim 32 further comprising means for sensing the input current from the USB power source, wherein an input of the current controller is coupled to said means for sensing the input current to reduce the output current to the battery as the voltage on the battery increases.

36. The circuit of claim 32 wherein the input current is maintained approximately constant as the output current is reduced.

37. The circuit of claim 32 wherein the output current is reduced before a transition from the current control mode to the voltage control mode.

38. The circuit of claim 37 wherein the output current is reduced after a precharge period.

39. The circuit of claim 32 wherein, during the current control mode, the output current is greater than a maximum current capability of the USB power source.

40. The circuit of claim 32 further comprising an analog-to-digital converter coupled to the first input of the switching regulator and a digital-to-analog converter coupled to an input of the current controller, wherein the output current is reduced incrementally.

41. The circuit of claim 32 further comprising an analog-to-digital converter coupled to the battery and a digital-to-analog converter coupled to an input of the current controller, wherein the output current is reduced incrementally.

42. The circuit of claim 32 further comprising a current sense circuit coupled to an input of the current controller, wherein the output current is reduced continuously.

43. The circuit of claim 32 further comprising an input current sense circuit and an output current sense circuit, wherein during a first time period of the current control mode, the output current sense circuit controls the output current to the battery to be constant, and wherein during a second time period of the current control mode after the first time period, the input sense circuit controls the output current to the battery to reduce as the voltage on the battery increases.

44. The circuit of claim 32 further comprising means for sensing the output voltage on the battery, wherein an input of the current controller is coupled to said means for sensing the output voltage to control the output current to the battery to reduce as the voltage on the battery increases.

45. The circuit of claim 32 wherein said circuit is an integrated circuit.