Patent ID: 8049462
Filing Date: 2011-11-01
Classification: H02J

Abstract:
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 a 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 only circuit initialization and circuit rebooting, and stores the maximum available current, and wherein when the charging current is higher than that the USB host can supply, the USB charging circuit is automatically shut down and rebooted, and the maximum available current is updated according to a detected condition during circuit rebooting.