Overvoltage Protection Utilized When A Battery Is Removed From A System

• US 20080246442A1
• Filed: 04/01/2008
• Published: 10/09/2008
• Est. Priority Date: 04/03/2007
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Vorenkamp, Pieter, Radke, Russell Eliot, Ackerman, Jay Edward
• Granted Patent: US 8,193,772 B2
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: H02J 7/00308 Overvoltage protection

Abstract

A system and method are provided for safely recharging a battery. A current source is coupled to a node and configured to produce a current. The battery is coupled to the node, and is configured to recharge during a recharging cycle based on receiving the current through the node. An overvoltage protection system is coupled between the node and the current source, and configured to disable the current source when a voltage at the node exceeds a threshold value. For example, the current source may be substantially instantaneously disabled when this occurs.

Claims

1. A system, comprising:

a current source coupled to a node and configured to produce a current;

a rechargeable battery coupled to the node and configured to receive the current through the node during a recharging cycle; and

an overvoltage protection system coupled between the node and the current source, and configured to disable the current source when a voltage at the node exceeds a threshold value.

2. The system of claim 1, wherein the current source produces the current based on a power supply coupled thereto.

3. The system of claim 1, wherein the current source is a slow loop system.

4. The system of claim 1, wherein the overvoltage protection system comprises:

a comparator is configured to compare the voltage at the node to the threshold value, produce a comparison signal therefrom, and disable the current source when the comparison signal indicates the voltage at the node exceeds the threshold value.

5. The system of claim 4, further comprising:

a disabling device coupled between the comparator and the current source, and configured to produce a disabling signal that disables the current source when the comparison signal indicates the voltage at the node exceeds the threshold value.

6. The system of claim 4, wherein:

the overvoltage protection system further comprises a voltage divider coupled between the node and the comparator, which is configured to produce a divided voltage from the voltage at the node; and

the comparator is configured to compare the divided voltage to the threshold value.

7. The system of claim 1, wherein the overvoltage protection system is a fast loop system.

8. The system of claim 1, further comprising:

a current sensor;

a voltage sensor; and

a controller coupled between the current source, the current sensor, and the voltage sensor, such that the controller is configured to control the current source during the recharging cycle.

9. The system of claim 8, wherein:

the controller is configured to perform a constant current procedure with respect to the current source using the current sensor during a first respective portion of the recharging cycle; and

the controller is configured to perform a constant voltage procedure with respect to the current source using the voltage sensor during a second respective portion of the recharging cycle.

10. The system of claim 1, further comprising:

a power management system coupled to the node, and configured to be powered by the rechargeable battery.

11. The system of claim 1, further comprising:

a handheld device coupled to the node, and configured to be powered by the rechargeable battery.

12. The system of claim 11, wherein the handheld device is a personal digital assistant, a phone, a computer, a MP3 player, or a video player.

13. The system of claim 1, wherein:

a handheld device, which operates at a first rated voltage, or a power management system, which operates at a second rated voltage, is coupled to the node, and is configured to be powered by the rechargeable battery; and

the threshold value is equal to or below a lower one of the first and second rated voltages.

14. The system of claim 1, further comprising:

a resistive device coupled between the current source and the node.

15. The system of claim 1, wherein the current source comprises a transistor.

16. A method comprising:

recharging a battery using a current flowing through a power node from a current source during a recharging cycle;

comparing a voltage at the power node to a threshold value to produce a comparison signal; and

controlling the current source based on the comparison signal, wherein when the voltage at the power node is above the threshold value the current source is disabled.

17. The method of claim 16, further comprising:

controlling the current source using a constant current procedure during a first respective portion of the recharging cycle; and

controlling the current source using a constant voltage procedure during a second respective portion of the recharging cycle.

18. The method of claim 16, further comprising using the battery to power a power management system coupled to the power node.

19. The method of claim 16, further comprising using the battery to power a handheld device coupled to the power node.

20. The method of claim 16, wherein, before the comparison step, the voltage at the power node is divided.

21. The method of claim 16, wherein the current source is substantially instantaneously disabled when the voltage at the power node exceeds the threshold value.

22. A circuit comprising:

a current source section coupled between a power source and a power node;

a rechargeable battery that is configured to be recharged using a current from the current source flowing through the power node, the rechargeable battery being coupled between the power node and ground; and

an overvoltage protection section coupled between the power node and the current source, and configured to substantially instantaneously disable the current source when a voltage at the power node exceeds a threshold value,

whereby the threshold value is equal to or below a rated voltage of a device coupled to and powered by the node.