Power management unit with battery detection

• US 20080197707A1
• Filed: 12/10/2007
• Published: 08/21/2008
• 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: Chi Yang, Ken Guo
• Granted Patent: US 8,188,706 B2
• Time in Patent Office: Days
• US Class Current: 307/71
• 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 to said electronic device;

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 a 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 to said electronic device, said method comprising steps of:

detecting if an external power source is coupled to a 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 to said electronic device;

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.