Battery protection circuits detection method and apparatus

• US 20080106235A1
• Filed: 11/03/2006
• Published: 05/08/2008
• Est. Priority Date: 11/03/2006
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Huang, Hung Sen
• Granted Patent: US 7,675,269 B2
• Time in Patent Office: Days
• US Class Current: 320/157
• CPC Class Codes: H02H 7/18 for batteries; for accumulators

Abstract

A method to detect the presence of battery protection circuits in any battery powered product. The major advantage of the method is to make the battery voltage very smooth during the charging process. The proposed circuit can give a good prediction of protection switching turn on time. This can provide the battery powered system work smoothly by avoiding any battery voltage discontinuity. The proposed invention addresses the issue of deep discharge and provides a solution through a discharge test procedure.

Claims

1. A battery protection circuit comprising:

a battery with varying charge levels;

a protector IC;

a first transistor connected to a first output pin of said protector IC;

a second transistor connected to a second output pin of said protector IC;

a first diode connected at the output of the first transistor; and

a second diode connected to the output of the second transistor.

2. The battery protection circuit of claim 1, wherein a positive terminal of the battery is connected to the drain of the second transistor.

3. The battery protection circuit of claim 1, wherein the source of the first transistor is connected to a maximum battery voltage value voltage source.

4. The battery protection circuit of claim 3, wherein a negative terminal of the battery is connected to a potential lower than maximum battery voltage value voltage source.

5. The battery protection circuit of claim 1, wherein the anode of the first diode is connected to the drain of the first transistor and the cathode of the first diode is connected to the source of the first transistor.

6. The battery protection circuit of claim 1, wherein the anode of the second diode is connected to the source of the second transistor and the cathode of the second diode is connected to the drain of the second transistor.

7. The battery protection circuit of claim 1, wherein said first and second transistors are Field Effect Transistors (FETs).

8. The battery protection circuit of claim 1, wherein said first and second transistors are Bipolar Junction Transistors (BJTs).

9. The battery protection circuit of claim 1, wherein the circuit is in an overcharge mode when the first transistor is ON and the second transistor is OFF.

10. The battery protection circuit of claim 1, wherein the circuit is in a deep discharge mode when the first transistor is OFF and the second transistor is ON.

11. A method to test the discharge level of a battery comprising:

setting a timer for a period of time;

detecting presence of a battery;

setting a discharge test threshold voltage value;

checking if a battery terminal voltage is lower than the discharge test threshold value;

checking if a discharge test path is closed;

trickle charging if the discharge test path is not closed; and

charging at a full voltage if the discharge test path is closed.

12. The method of claim 11, wherein the discharge test threshold value is set to 2 Volts.

13. The method of claim 11, wherein the testing period is 5 minutes for trickle charging.

14. The method of claim 11, wherein the discharge test is performed only when the battery terminal voltage is less than the discharge test threshold value.

15. The method of claim 11, wherein said period of time is approximately 1 hour.