A system, comprising: a computer having a CPU, the computer being configured to send a power management signal according to a global system state of the computer, wherein the global system state comprises standby state, sleep state or soft off state; and a universal serial bus charger, comprising: a control unit, configured for receiving the power management signal generated by the CPU of the computer, and for outputting a switching signal and a charging signal according to the power management signal; a charger module, configured for outputting power and a power suspending signal according to the charging signal and a communications protocol signal, respectively; a universal serial bus interface device, configured for operating according to the power, and outputting the communications protocol signal according to a universal serial bus peripheral device connected thereto; and a switch device, coupled between the charger module and the universal serial bus interface device, configured for receiving the power and for providing the power to the universal serial bus interface device according to the switching signal and the power suspending signal, the universal serial bus charger being characterized in that the switch device is configured to stop providing the power to the universal serial bus interface device for a predetermined time after receiving the switching signal, and to then restart providing the power to the universal serial bus interface device thereafter. a computer having a CPU, the computer being configured to send a power management signal according to a global system state of the computer, wherein the global system state comprises standby state, sleep state or soft off state; and a universal serial bus charger, comprising: a control unit, configured for receiving the power management signal generated by the CPU of the computer, and for outputting a switching signal and a charging signal according to the power management signal; a charger module, configured for outputting power and a power suspending signal according to the charging signal and a communications protocol signal, respectively; a universal serial bus interface device, configured for operating according to the power, and outputting the communications protocol signal according to a universal serial bus peripheral device connected thereto; and a switch device, coupled between the charger module and the universal serial bus interface device, configured for receiving the power and for providing the power to the universal serial bus interface device according to the switching signal and the power suspending signal, a control unit, configured for receiving the power management signal generated by the CPU of the computer, and for outputting a switching signal and a charging signal according to the power management signal; a charger module, configured for outputting power and a power suspending signal according to the charging signal and a communications protocol signal, respectively; a universal serial bus interface device, configured for operating according to the power, and outputting the communications protocol signal according to a universal serial bus peripheral device connected thereto; and a switch device, coupled between the charger module and the universal serial bus interface device, configured for receiving the power and for providing the power to the universal serial bus interface device according to the switching signal and the power suspending signal, the universal serial bus charger being characterized in that the switch device is configured to stop providing the power to the universal serial bus interface device for a predetermined time after receiving the switching signal, and to then restart providing the power to the universal serial bus interface device thereafter.