Power management unit with battery detection controller and switchable regulator block

• US 8,188,706 B2
• Filed: 12/10/2007
• Issued: 05/29/2012
• Est. Priority Date: 02/16/2007
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Yang, Ken Guo Chi
• Primary Examiner(s): WILLIAMS, ARUN C
• Application Number:
  US12/001,353
• Publication Number:
  US 20080197707A1
• Time in Patent Office: 1,632 Days
• Field of Search: 320/107
• US Class Current: 320/107
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

According to one exemplary embodiment, a power management unit residing in an electronic device includes a battery detection controller coupled to a battery charger and a regulator block, where the regulator block is capable of providing power to the electronic device. The battery detection controller is configured to turn off the regulator block when the battery charger is coupled to an external power source and is not coupled to a battery of the electronic device. The battery detection controller can be further configured to turn on the regulator block when the battery charger is coupled to the external power source and is coupled to the battery if the battery has a battery voltage greater than a threshold voltage.

Claims

1. A power management unit residing in an electronic device, said power management unit comprising:

a battery detection controller coupled to a battery charger and a regulator block, said regulator block being capable of providing power only to said electronic device, said regulator block not providing power to said battery charger;

said battery detection controller being configured to turn off said regulator block when said battery charger is coupled to an external power source and is not coupled to a battery of said electronic device.

2. The power management unit of claim 1, wherein said battery detection controller is further configured to turn on said regulator block when said battery charger is coupled to said external power source and is coupled to said battery if said battery has a battery voltage greater than a threshold voltage.

3. The power management unit of claim 1, wherein said battery detection controller is further configured to turn off said regulator block when said battery charger is coupled to said external power source and is coupled to said battery if said battery has a battery voltage less than a threshold voltage.

4. The power management unit of claim 3, wherein said battery detection controller is further configured to turn on said regulator block after said battery has been charged to said battery voltage greater than said threshold voltage.

5. The power management unit of claim 1, wherein said battery detection controller causes a capacitor coupled to said battery charger battery to be discharged for a predetermined time interval to determine if said battery charger is coupled to said battery.

6. The power management unit of claim 5 further comprising a comparator, wherein said battery detection controller determines that said battery charger is not coupled to said battery when an output of said comparator is at a low voltage level after said capacitor has been discharged for said predetermined time interval.

7. The power management unit of claim 5 further comprising a current sink, wherein said battery detection controller causes said current sink to discharge said capacitor for said predetermined time interval.

8. A method for controlling a regulator block in a power management unit residing in an electronic device, said regulator block being capable of providing power only to said electronic device, said regulator block not providing power to a battery charger in said power management unit, said method comprising steps of:

detecting if an external power source is coupled to said battery charger in said power management unit;

determining if said battery charger is coupled to a battery of said electronic device;

turning off said regulator block if said battery charger is coupled to said external power source and is not coupled to said battery of said electronic device.

9. The method of claim 8 further comprising a step of turning on said regulator block if said battery charger is coupled to said external power source and is coupled to said battery if said battery has a battery voltage greater than a threshold voltage.

10. The method of claim 8 further comprising a step of turning off said regulator block when said battery charger is coupled to said external power source and is coupled to said battery if said battery has a battery voltage less than a threshold voltage.

11. The method of claim 10 further comprising a step of turning on said regulator block after charging said battery to a battery voltage greater than said threshold voltage.

12. The method of claim 8, wherein said determining step is performed by a battery detection controller in said power management unit, wherein said battery detection controller controls said regulator block.

13. The method of claim 8, wherein said determining step comprises the steps of:

discharging for a predetermined time interval a capacitor coupled to said battery charger;

sampling an output of a comparator in said power management unit;

determining that said battery charger is not coupled to said battery if said output of said comparator is at a low voltage level.

14. The method of claim 13, wherein said sampling step is performed by a battery detection controller in said power management unit.

15. A power management unit residing in an electronic device, said power management unit comprising:

a battery detection controller coupled to a battery charger and a regulator block, said regulator block being capable of providing power only to said electronic device, said regulator block not providing power to said battery charger;

said battery detection controller being configured to turn off said regulator block when said battery charger is coupled to an external power source and is not coupled to a battery of said electronic device;

said battery detection controller being further configured to turn on said regulator block when said battery charger is coupled to said external power source and is coupled to said battery if a battery voltage of said battery is greater than a threshold voltage.

16. The power management unit of claim 15, wherein said battery detection controller is further configured to turn off said regulator block when said battery charger is coupled to said external power source and is coupled to said battery if said battery voltage of said battery is less than said threshold voltage.

17. The power management unit of claim 15 further comprising a comparator having an output coupled to an input of said battery detection, a first input coupled to said threshold voltage, and a second input coupled to an output of said battery charger.

18. The power management unit of claim 17, wherein said battery detection controller is further configured to turn off said regulator block if said output of said comparator is at a low voltage level after a capacitor coupled to said second input of said comparator has been discharged for a predetermined time interval.

19. The power management unit of claim 17, wherein said second input of said comparator is coupled to a current sink, wherein said current sink is configured to discharge a capacitor coupled to said output of said battery charger for a predetermined time interval when said current sink is turned on by said battery detection controller.

20. The power management unit of claim 15, wherein said battery detection controller is further configured to turn on said battery charger when said battery detection controller detects that said external power source is coupled to said battery charger.

21. An electronic device comprising:

a battery detection controller coupled to a battery charger;

said battery detection controller providing a charger control signal to said battery charger;

said charger control signal causing said battery charger to provide a charging current during a predetermined charge time so as to determine whether a battery is coupled to said battery charger;

said charger control signal dependent on charging a capacitor to a voltage at a common node greater than a threshold voltage, discharging said capacitor through a current sink coupled directly to a ground voltage for a predetermined discharge time, and sampling a difference of said voltage and said threshold voltage.

22. The electronic device of claim 21 wherein said capacitor is coupled to and shares said common node with said battery.

23. The electronic device of claim 22 wherein said voltage at said common node is sampled by said battery detection controller.

24. The electronic device of claim 22 wherein said voltage at said common node exceeds said threshold voltage during said pre-determined charge time if said battery is not coupled to said battery charger.

25. The electronic device of claim 22 wherein said voltage at said common node does not exceed said threshold voltage during said pre-determined charge time if said battery is coupled to said battery charger.

26. The electronic device of claim 22 wherein a comparator coupled to said common node is utilized to compare said voltage at said common node to said threshold voltage.

27. The electronic device of claim 26 wherein an output of said comparator is coupled to said battery detection controller.

28. The electronic device of claim 27 wherein said battery detection controller determines whether said battery is coupled to said battery charger based on said output of said comparator.

29. The electronic device of claim 21 wherein said battery detection controller is part of a power management unit in said electronic device.

30. The electronic device of claim 21 wherein said battery charger is part of a power management unit in said electronic device.

31. The electronic device of claim 21 wherein said predetermined charge time is greater than approximately 15.0 ms.

32. The electronic device of claim 21 wherein said common node corresponds to an output node of said battery.

33. The electronic device of claim 32 wherein a voltage at said output node exceeds a threshold voltage during said pre-determined charge time if said battery is not coupled to said battery charger.

34. The electronic device of claim 32 wherein a voltage at said output node does not exceed a threshold voltage during said pre-determined charge time if said battery is coupled to said battery charger.

35. The electronic device of claim 32 wherein a comparator coupled to said output node is utilized to compare said voltage at said output node to said threshold voltage.

36. The electronic device of claim 35 wherein an output of said comparator is coupled to said battery detection controller.

37. The electronic device of claim 36 wherein said battery detection controller determines whether said battery is coupled to said battery charger based on said output of said comparator.

38. The electronic device of claim 32 wherein said battery detection controller is part of a power management unit in said electronic device.

39. The electronic device of claim 32 wherein said battery charger is part of a power management unit in said electronic device.

40. A method for determining whether a battery is coupled to a battery charger in an electronic device, said method comprising:

causing said battery charger to provide a charging current during a predetermined charge time to a common node shared by said battery and a capacitor, thereby charging said voltage at said common node greater than a threshold voltage;

causing said battery charger to discharge said capacitor through a current sink coupled directly to a ground voltage for a predetermined discharge time;

sampling a difference of said voltage at said common node and said threshold voltage to determine whether said battery is coupled to said battery charger.

41. The method of claim 40 wherein a battery detection controller causes said battery charger to provide said charging current during said pre-determined charge time.

42. The method of claim 40 wherein said sampling said voltage comprises determining whether said voltage at said common node exceeds said threshold voltage during said pre-determined charge time.

43. The method of claim 42 wherein said voltage at said common node exceeds said threshold voltage during said pre-determined charge time if said battery is not coupled to said battery charger.

44. The method of claim 42 wherein said voltage at said common node does not exceed said threshold voltage during said pre-determined charge time if said battery is coupled to said battery charger.

45. The method of claim 40 wherein said measuring said voltage comprises using a comparator to determine whether said voltage at said common node exceeds a threshold voltage.

46. The electronic device of claim 45 wherein an output of said comparator is coupled to a battery detection controller in said electronic device.

47. The electronic device of claim 46 wherein said battery detection controller determines whether said battery is coupled to said battery charger based on said output of said comparator.

48. The method of claim 40 wherein said predetermined charge time is greater than approximately 15.0 ms.