SYSTEMS AND METHODS FOR POWER SHARING RELATED TO MULTIPORT CHARGERS

USB charging system and method. For example, a USB charging system includes: a first AC-to-DC conversion unit configured to generate a first voltage and a first current; a second AC-to-DC conversion unit configured to generate a second voltage and a second current; a first USB output port corresponding to the first AC-to-DC conversion unit; a second USB output port corresponding to the second AC-to-DC conversion unit; a switch connected to the first AC-to-DC conversion unit and the second AC-to-DC conversion unit; and a control chip connected to the first AC-to-DC conversion unit and the second AC-to-DC conversion unit and configured to open the switch and close the switch; wherein the control chip is further configured to: determine whether the first USB output port is connected to a load device and whether the second USB output port is connected to a load device.