Systems and methods for selectively changing current limit of a battery controller

• US 7,728,558 B2
• Filed: 01/05/2007
• Issued: 06/01/2010
• Est. Priority Date: 01/05/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Tam, John, Johnson, Timothy
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): Berhanu; Samuel
• Application Number:
  US11/650,131
• Publication Number:
  US 20080164855A1
• Time in Patent Office: 1,243 Days
• Field of Search: None
• US Class Current: 320/138
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision

Abstract

Systems and methods for selectively changing the current threshold of current limiting circuitry are provided. The current limit threshold of current limiting circuitry may be selectively changed based on a detected power source using a resistive network. The current limiting threshold may be selected by changing a resistance value of a resistive network electrically coupled to an input on the current limiting circuitry (e.g., battery controller) for programming the current limiting threshold. The resistance value received by the currently limiting circuitry at this input may set the current threshold and thus the maximum magnitude of current that may be provided to charge a battery or other energy storage device located in the electronic device (e.g., a mobile phone).

Claims

1. A system for selectively changing a current limit threshold, the system comprising:

power source detection circuitry operative to detect a power source selected from at least two power sources;

a resistive network operative to selectively provide one of at least two resistance values based on the detected power source; and

current limiting circuitry electrically coupled to receive the resistance value from the resistive network, the current limiting circuitry operative to set the current limiting circuitry to one of at least two current limiting thresholds based on the resistance value.

2. The system of claim 1, further comprising a dock for receiving a connector electrically coupled to one of the at least two power sources.

3. The system of claim 1, further comprising an energy storage device electrically coupled to the current limiting circuitry.

4. The system of claim 1, wherein the resistive network comprises:

a first resistor electrically coupled to the current limiting circuitry;

a second resistor electrically coupled to the first resistor and a ground source; and

a switch electrically coupled between the first resistor and the ground source, the switch operative to electrically couple and decouple the first switch to the ground source based on the detected power source.

5. The system of claim 4, further comprising a processor electrically coupled to the detection circuitry and the switch, the processor operative to provide a signal to selectively turn the switch ON and OFF.

6. The system of claim 1, wherein the detection circuitry comprises:

a first power node;

a second power node;

a converter;

a first resistor electrically coupled to the first power node;

a first switch electrically coupled to the first resistor and a third resistor, the resistor electrically coupled to the converter;

a second resistor electrically coupled to the second power node;

a second switch electrically coupled to the second resistor and the third resistor;

wherein the first and second switches are selectively OPENED and CLOSED to enable the converter to measure a voltage on the first and second voltage supply nodes.

7. The system of claim 6, further comprising a processor electrically coupled to receive a signal from the converter to determine which one of the at least two power sources is received by the system.

8. A method for selectively changing a current limiting threshold, the method comprising:

detecting a received power source selected from at least two power sources;

selectively providing one of at least two resistance values to current limiting circuitry based on the detected power source; and

setting the current limiting threshold to one of at least two current limiting thresholds based on the resistance value provided to the current limiting circuitry.

9. The method of claim 8, wherein selectively providing the resistance value comprises using a resistive network operative to provide one of at least two resistance values.

10. The method of claim 8, wherein detecting comprises:

generating a first detect signal based on a power signal provided by the received power source;

generating a second detect signal based on the power signal provided by the received power source; and

analyzing the first and second detect signals to detect which power source is received.

11. The method of claim 8, wherein the detected power source is a high power source and the resistance value is set to a value that sets the current limiting threshold to a high current limiting threshold.

12. The method of claim 8, wherein the detected power source is a low power source and the resistance value is set to a value that sets the current limiting threshold to a low current limiting threshold.

13. The method of claim 8, further comprising:

receiving power, at the current limiting circuitry, from the power source; and

limiting a magnitude of the power outputted by the current limiting circuitry based on the current limiting threshold.

14. The method of claim 13, further comprising:

providing the power having the limited magnitude to an energy storage device.

15. The method of claim 14, further comprising:

adjusting the resistance value using duty cycle control.

16. The method of claim 14, further comprising:

providing a charging current based on the current limit threshold set for the current limiting circuitry; and

adjusting the charging current using duty cycle control.

17. A portable electronic device, comprising:

a processor operative to generate at least one selection signal based on a detected power source;

a resistive network electrically coupled to the processor, the network operative to provide one of at least two resistance values in response to the at least one selection signal; and

battery controller circuitry electrically coupled to the resistive network to receive the resistance value and operative to provide a power signal, the power signal having a magnitude limited to a current limiting threshold based on the resistance value, the battery controller circuit operative to set the current limiting threshold to one of at least two current limiting thresholds based on the resistance value.

18. The portable electronic device of claim 17, wherein the resistive network comprises:

a first resistor electrically coupled to the battery contoller circuitry;

a second resistor electrically coupled to the first resistor and a ground source; and

a switch electrically coupled between the first resistor and the ground source, the switch operative to electrically couple and decouple the first resistor to the ground source in response to the at least one signal provided by the processor.

19. The portable electronic device of claim 17, wherein the resistive network comprises:

a variable resistor electrically coupled to the battery controller circuitry and the processor.

20. The portable electronic device of claim 17, wherein the resistive network comprises:

a resistor ladder electrically coupled to the battery controller circuitry and the processor.

21. The portable electronic device of claim 17, wherein the threshold is inversely proportional to the resistance value provided to the battery controller circuitry.

22. The portable electronic device of claim 17, wherein the threshold is proportional to the resistance value provided to the battery controller circuitry.

23. The portable electronic device of claim 17, wherein the electronic device is a mobile telephone or a personal media device.

24. The portable electronic device of claim 17, wherein the detected power source is USB power source.

25. The portable electronic device of claim 17, wherein the detected power source is a FIRE WIRE power source.

26. The portable electronic device of claim 17, wherein the detected power source is selected from the group of power sources capable of supplying 100 mA, 500 mA, 1000 mA, or any combination thereof.