Power saving system and method for devices based on universal serial bus

A system for adjusting power consumption of a USB-based device, the system comprising:

• a power supply configured to generate a first supply voltage;
• a controller configured to receive the first supply voltage and generate a control signal;
• a USB component configured to receive the control signal and in response operate in a first USB mode or a second USB mode;
• wherein:
• the power supply is further configured to generate the first supply voltage at a first voltage level if the first supply voltage is converted from an AC voltage;
• the power supply is further configured to generate the first supply voltage at a second voltage level if the first supply voltage is directly supplied by a battery, or is converted from a first DC voltage supplied by the battery;
• the controller is further configured to process information associated with the first supply voltage and a predetermined threshold voltage;
• if the first supply voltage is higher than the predetermined threshold voltage, the control signal represents a first logic state;
• if the first supply voltage is lower than the predetermined threshold voltage, the control signal represents a second logic state;
• the USB component is further configured to operate in the first USB mode if the control signal represents the first logic state, and to operate in the second USB mode if the control signal represents the second logic state;
• the first USB mode is associated with a first power consumption level;
• the second USB mode is associated with a second power consumption level;
• the first voltage level is higher than the second voltage level;
• the first power consumption level is higher than the second power consumption level.

A method for adjusting power consumption of a USB-based device, the method comprising:

• generating a first supply voltage;
• processing information associated with the first supply voltage;
• generating a control signal based on at least information associated with the first supply voltage;
• receiving the control signal;
• in response to the control signal, switching between a first USB mode and a second USB mode;
• wherein:
• the generating a control signal includes processing information associated with the first supply voltage and a predetermined threshold voltage;
• if the first supply voltage is higher than the predetermined threshold voltage, the control signal represents a first logic state;
• if the first supply voltage is lower than the predetermined threshold voltage, the control signal represents a second logic state;
• wherein the switching between a first USB mode and a second USB mode includes:
• switching from the first USB mode to the second USB mode if the control signal changes from representing the first logic state to representing the second logic state;
• switching from the second USB mode to the first USB mode if the control signal changes from representing the second logic state to representing the first logic state;
• wherein:
• the first USB mode is associated with a first power consumption level;
• the second USB mode is associated with a second power consumption level;
• the first power consumption level and the second power consumption level are different.