Universal serial bus charger circuit and charging method

• US 20090102431A1
• Filed: 09/18/2008
• Published: 04/23/2009
• Est. Priority Date: 10/19/2007
• Status: Active Grant

• Current Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Original Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Inventors: Chu, Kwan-Jen, Liu, Jing-Meng, Kung, Nien-Hui
• Granted Patent: US 8,049,462 B2
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

The present invention discloses a universal serial bus (USB) charging circuit, comprising: a charging path for charging a battery from a USB host; a charging switch located on the charging path; a current sensing circuit for sensing current information on the charging path; a maximum available current detection circuit for detecting the maximum available current from the USB host; and a loop controller circuit for controlling the charging switch so that the charging current on the charging path is substantially equal to the maximum available current detected by the maximum available current detection circuit, wherein the maximum available current detection circuit detects the maximum available current during circuit initialization and stores it.

Claims

1. A universal serial bus (USB) charging circuit, comprising:

a charging path for charging a battery from a USB host;

a charging switch located on the charging path;

a current sensing circuit for sensing current information on the charging path;

a maximum available current detection circuit for detecting the maximum available current from the USB host; and

a loop controller circuit for controlling the charging switch so that the charging current on the charging path is substantially equal to the maximum available current detected by the maximum available current detection circuit,

wherein the maximum available current detection circuit detects the maximum available current during circuit initialization and stores it.

2. The USB charging circuit of claim 1, wherein when the charging current is higher than that the USB host can supply, the USB charging circuit is automatically shut down and rebooted.

3. The USB charging circuit of claim 1, wherein the USB charging circuit is periodically shut down and rebooted.

4. The USB charging circuit of claim 1, further comprising a current setting circuit for setting an upper limit of the charging current.

5. The USB charging circuit of claim 4, further comprising a timer for providing time information to the loop control circuit, wherein when the timer counts a preset time, the loop control circuit lifts the charging current to the upper limit.

6. The USB charging circuit of claim 1, wherein the loop control circuit obtains information of the battery voltage from one end of the battery.

7. A USB charging method comprising:

providing a charging circuit, which includes a charging path for charging a battery from a USB host;

detecting the maximum available current from the USB host during circuit initialization and stores it; and

making a charging current on the charging path equal to the stored maximum available current.

8. The USB charging method of claim 7, further comprising:

when the charging current is higher than that the USB host can supply, automatically shutting down and rebooting the USB charging circuit.

9. The USB charging method of claim 7, further comprising:

periodically shutting down and rebooting the USB charging circuit.

10. The USB charging method of claim 7, further comprising:

setting an upper limit for the charging current.

11. The USB charging method of claim 10, further comprising:

periodically lifting the charging current to the upper limit.

12. The USB charging method of claim 7, further comprising:

obtaining information of the battery voltage from one end of the battery.