Battery Charging Systems and Methods with Adjustable Current Limit

• US 20080258688A1
• Filed: 04/21/2008
• Published: 10/23/2008
• Est. Priority Date: 04/19/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Summit Microelectronics, Incorporated (Qualcomm, Inc.)
• Inventors: Kanamori, Takashi, Hussain, M. Abid, O'Brien, Thomas J., Paparrizos, George Konstantinos
• Granted Patent: US 7,990,106 B2
• Time in Patent Office: Days
• US Class Current: 320/145
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H02J 7/06 using discharge tubes or semiconductor devices

Abstract

Embodiments of the present invention include techniques for charging a battery using a regulator. In one embodiment, the present invention includes an electronic circuit comprising a regulator having an input coupled to a power source for receiving a voltage and a current and an output for providing an output current, an input voltage detection circuit coupled to the power source, and an adjustable current limit circuit for controlling the input or output current of the regulator, wherein input voltage detection circuit monitors the voltage from the power source and the adjustable current limit circuit changes the input or output current of the regulator to optimize the power drawn from power source.

Claims

1. An electronic circuit comprising:

a regulator having an input coupled to a power source for receiving a voltage and a current and an output for providing an output current;

an input voltage detection circuit coupled to the power source; and

an adjustable current limit circuit for controlling the input or output current of the regulator,

wherein input voltage detection circuit monitors the voltage from the power source and the adjustable current limit circuit changes the input or output current of the regulator if the voltage from the power source is below a threshold value.

2. The electronic circuit of claim 1 wherein the output of the regulator is coupled to a battery and wherein the regulator is configured to produce a constant current into said battery.

3. The electronic circuit of claim 2 wherein the adjustable current limit circuit controls the output current of the regulator, and wherein the output current limit is larger than the input current when the battery voltage is lower than the voltage from the power source.

4. The electronic circuit of claim 1 wherein a current limit is set to an initial value and incrementally, changed until the current limit is set to a value that optimizes the power available from the power source.

5. The electronic circuit of claim 4 wherein the current limit is programmed by storing digital bits.

6. The electronic circuit of claim 4 wherein the current limit is set to an initial value above the maximum current available from the power source and incrementally decreased until the voltage from the power source increases above the threshold value.

7. The electronic circuit of claim 4 wherein the current limit is set to an initial value below the maximum current available from the power source and incrementally increased until the voltage from the power source decreases below the threshold value, wherein the current limit is set to an immediately preceding value used before the voltage from the power source decreased below the threshold voltage.

8. The electronic circuit of claim 1 wherein the regulator is a switching regulator.

9. The electronic circuit of claim 1 wherein the regulator is a switching regulator.

10. The electronic circuit of claim 1 wherein the adjustable current limit circuit controls the input current of the regulator.

11. The electronic circuit of claim 1 wherein the adjustable current limit circuit controls the output current of the regulator.

12. A method of controlling current in an electronic circuit comprising:

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

monitoring the voltage from the power source; and

changing an input or output current of the regulator if the voltage from the power source is below a threshold value.

13. The method of claim 12 wherein an output of the regulator is coupled to a battery and wherein the regulator is configured to produce a constant current into said battery.

14. The method of claim 13 further comprising setting an output current limit of the regulator, wherein the output current limit is larger than the input current when the battery voltage is lower than the voltage from the power source.

15. The method of claim 14 further comprising determining an input current limit if the voltage on the battery causes the input current to increase above a maximum available current from said power source.

16. The method of claim 12 wherein the input or output current is set using a current limit.

17. The method of claim 16 wherein the current limit is set to an initial value and incrementally changed until the current limit is set to a value that optimizes the power available from the power source.

18. The method of claim 17 wherein the current limit is programmed by storing digital bits.

19. The method of claim 17 wherein the current limit is set to an initial value above the maximum current available from the power source and incrementally decreased until the voltage from the power source increases above the threshold value.

20. The method of claim 17 wherein the current limit is set to an initial value below the maximum current available from the power source and incrementally increased until the voltage from the power source decreases below the threshold value, wherein the current limit is set to an immediately preceding value used before the voltage from the power source decreased below the threshold voltage.

21. The method of claim 12 further comprising:

generating a first voltage proportional to a first current at the input or output of the regulator;

comparing the first voltage to a reference voltage, wherein the reference voltage is generated based on a stored plurality of bits corresponding to a programmed current limit;

controlling the regulator using the first current if the first voltage is greater than the reference voltage.

22. The method of claim 21 wherein the stored plurality of bits are set to an initial value and incrementally changed until the reference voltage is set to a value that optimizes the power available from the power source.

23. The method of claim 12 wherein monitoring the voltage from the power source comprises:

detecting the voltage at the input of the regulator,

generating a signal if the voltage at the input of the regulator is below an expected voltage;

changing digital bits in response to the generated signal; and

changing an input or output current of the regulator using the digital bits.

24. The method of claim 23 wherein the digital bits are stored in a counter, and wherein the counter is incremented in response to receiving the signal.

25. The method of claim 23 further comprising shutting down the regulator if the voltage at the input of the regulator is below the expected voltage and restarting the regulator after a time period.

26. The method of claim 23 wherein the signal is generated on a first integrated circuit and processed on external electronics, and wherein said external electronics change said digital bits.