Chargers, systems and methods for detecting a power source

• US 8,242,742 B2
• Filed: 05/30/2008
• Issued: 08/14/2012
• Est. Priority Date: 06/06/2007
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Kao, Han-Jung, Li, Guoxing, Kao, Ya-Tung, Zhang, Wei
• Primary Examiner(s): WILLIAMS, ARUN C
• Application Number:
  US12/156,225
• Publication Number:
  US 20080303486A1
• Time in Patent Office: 1,537 Days
• Field of Search: 320/114
• US Class Current: 320/114
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence

Abstract

A charger includes a detection pin, a voltage divider, and a comparator. The detection pin can couple the charger to a power source via a first data line. The voltage divider and the comparator are coupled to the detection pin. The voltage divider divides a power voltage provided by the power source and provides a detection voltage at the detection pin. The comparator compares the detection voltage with a predetermined reference voltage and identifies a type of the power source according to the comparing.

Claims

1. A method for detecting a power source which is selected from the group consisting of a universal serial bus (USB) host and an alternating current (AC) adapter, said method comprising:

receiving a power voltage from a power line of said power source;

exchanging data via a first data line and a second data line between said power source and a USB client;

generating a detection voltage on said first data line by a voltage divider, wherein said voltage divider comprises a first resistor coupled between a power pin and a detection pin, and a second resistor coupled between said detection pin and ground, wherein said power source comprises a transmitter in which said first data line and said second data line are coupled to each other if said power source is said AC adapter, and wherein said USB client comprises a third resistor;

determining a voltage level of said detection voltage according to resistance values of said first resistor, said second resistor and said third resistor if said power source is said AC adapter;

comparing said detection voltage on said data line with a first predetermined reference voltage; and

identifying whether said power source is said USB host or said AC adapter according to a result of said comparing of said detection voltage with said first predetermined reference voltage.

2. The method of claim 1, further comprising:

comparing said detection voltage with a second predetermined reference voltage; and

identifying a type of said USB client coupled to said first data line according to a result of said comparing of said detection voltage with said second predetermined reference voltage.

3. The method of claim 1, wherein said third resistor is coupled to said second data line.

4. The method of claim 3, wherein said USB host comprises a fourth resistor coupled to said first data line, and wherein said determining step further comprising:

determining said voltage level according to resistance values of said first resistor, said second resistor and said fourth resistor if said power source is said USB host.

5. The method of claim 1, wherein said third resistor is coupled to said first data line.

6. The method of claim 5, wherein said USB host comprises a fourth resistor coupled to said first data line, and wherein said determining step further comprising:

determining said voltage level according to resistance values of said first resistor, said second resistor, said third resistor and said fourth resistor if said power source is said USB host.

7. A charger comprising:

a power pin coupled to a power line of a power source, said power pin receiving a power voltage provided by said power source, said power source is selected from the group consisting of a universal serial bus (USB) host and an alternating current (AC) adapter;

a detection pin coupled to a first data line of said power source, said first data line and a second data line transferring data between said power source and a USB client;

a voltage divider coupled to said detection pin and said power pin, said voltage divider comprising a first resistor coupled between said power pin and said detection pin, and a second resistor coupled between said detection pin and ground, and providing a detection voltage at said detection pin by dividing said power voltage at said power pin according to resistors in said power source and said USB client; and

a first comparator coupled to said detection pin, said first comparator comparing said detection voltage at said detection pin with a first predetermined reference voltage and identifying whether said power source is said USB host or said AC adapter according to a result of said comparison,

wherein said power source comprises a transmitter in which said first data line and said second data line are coupled to each other if said power source is said AC adapter, wherein said USB client comprises a third resistor coupled to said first data line, and wherein said voltage divider provides said detection voltage by dividing said power voltage according to resistance values of said first resistor, said second resistor and said third resistor if said power source is said AC adapter.

8. The charger of claim 7, wherein said voltage divider is coupled to said power pin via a first switch and is coupled to ground via a second switch.

9. The charger of claim 7, wherein said USB client receives said power voltage via said power line.

10. The charger of claim 7, further comprising:

a second comparator coupled to said detection pin, said second comparator identifying a type of said USB client by comparing said detection voltage with a second predetermined reference voltage.

11. The charger of claim 7, wherein said USB client is selected from a group consisting of:

a full speed USB client, a high speed USB client, and a low speed USB client.

12. The charger of claim 7, wherein a charging current is set by said charger according to said identification of said power source.

13. The charger of claim 7, wherein said power source comprises a fourth resistor coupled to said first data line if said power source is said USB host, and wherein said voltage divider provides said detection voltage by dividing said power voltage according to resistance values of said first resistor, said second resistor, said third resistor and said fourth resistor if said power source is said USB host.

14. A system comprising:

a power source providing a power voltage on a power line, wherein said power source is selected from the group consisting of a universal serial bus (USB) host and an alternating current (AC) adapter;

a USB client receiving said power voltage from said power line and exchanging data with said power source via a first data line and a second data line; and

a charger coupled to said power line and said first data line, said charger receiving said power voltage from said power line, dividing said power voltage on said power line to a detection voltage on said first data line according to resistors in said power source and said USB client, identifying whether said power source is said USB host or said AC adapter by comparing said detection voltage with a first predetermined reference voltage, and identifying a type of said USB client by comparing said detection voltage with a second predetermined reference voltage,

wherein said charger comprises a first resistor coupled between said power line and said first data line, and a second resistor coupled between said first data line and ground,

wherein said power source comprises a third resistor coupled to said first data line if said power source is said USB host and wherein said power source comprises a transmitter in which said first data line and said second data line are coupled to each other if said power source is said AC adapter, wherein said USB client comprises a fourth resistor coupled to said second data line, wherein said voltage divider provides said detection voltage by dividing said power voltage according to resistance values of said first resistor, said second resistor and said third resistor if said power source is said USB host, and wherein said voltage divider provides said detection voltage by dividing said power voltage according to resistance values of said first resistor, said second resistor and said fourth resistor if said power source is said AC adapter.

15. A system comprising:

a power source providing a power voltage on a power line, wherein said power source is selected from the group consisting of a universal serial bus (USB) host and an alternating current (AC) adapter;

a USB client receiving said power voltage from said power line and exchanging data with said power source via a first data line and a second data line; and

a charger coupled to said power line and said first data line, said charger receiving said power voltage from said power line, dividing said power voltage on said power line to a detection voltage on said first data line according to resistors in said power source and said USB client, identifying whether said power source is said USB host or said AC adapter by comparing said detection voltage with a first predetermined reference voltage, and identifying a type of said USB client by comparing said detection voltage with a second predetermined reference voltage,

wherein said charger comprises a first resistor coupled between said power line and said first data line, and a second resistor coupled between said first data line and ground,

wherein said power source comprises a third resistor coupled to said first data line if said power source is said USB host and wherein said power source comprises a transmitter in which said first data line and said second data line are coupled to each other if said power source is said AC adapter, wherein said USB client comprises a fourth resistor coupled to said first data line, wherein said voltage divider provides said detection voltage by dividing said power voltage according to resistance values of said first resistor, said second resistor, said third resistor and said fourth resistor if said power source is said USB host, and wherein said voltage divider provides said detection voltage by dividing said power voltage according to resistance values of said first resistor, said second resistor and said fourth resistor if said power source is said AC adapter.

16. A charger comprising:

a power pin coupled to a power line of a power source, said power pin receiving a power voltage provided by said power source, said power source is selected from the group consisting of a universal serial bus (USB) host and an alternating current (AC) adapter;

a detection pin coupled to a first data line of said power source, said first data line and a second data line transferring data between said power source and a USB client;

a voltage divider coupled to said detection pin and said power pin, said voltage divider comprising a first resistor coupled between said power pin and said detection pin, and a second resistor coupled between said detection pin and ground, and providing a detection voltage at said detection pin by dividing said power voltage at said power pin according to resistors in said power source and said USB client; and

a first comparator coupled to said detection pin, said first comparator comparing said detection voltage at said detection pin with a first predetermined reference voltage and identifying whether said power source is said USB host or said AC adapter according to a result of said comparison,

wherein said power source comprises a transmitter in which said first data line and said second data line are coupled to each other if said power source is said AC adapter, wherein said USB client comprises a third resistor coupled to said second data line, and wherein said voltage divider provides said detection voltage by dividing said power voltage according to resistance values of said first resistor, said second resistor and said third resistor if said power source is said AC adapter.

17. The charger of claim 16, wherein said power source comprises a fourth resistor coupled to said first data line if said power source is said USB host, and wherein said voltage divider provides said detection voltage by dividing said power voltage according to resistance values of said first resistor, said second resistor and said fourth resistor if said power source is said USB host.