Abstract: A battery management system includes a power converter, a first switch, a second switch, a first detecting unit, and a CPU. The power converter is configured to divide current provided by the power supply into a first and a second output current, according to a working current of a system load in a normal state, the first output current is used to power the system load, and the second output current is used to charge a battery unit. The CPU is configured to determine whether the value of current detected by the first detecting unit is greater than a threshold value, and further controls turning on the first switch to power the system load using the first output current, and turn on the second switch to charge the battery unit using the second output current.

Abstract: An under-voltage protection circuit has a power input terminal connected to a battery, a power output terminal connected to an electronic device, a switch circuit for switching the power supply circuit from the power input terminal to the power output terminal, a control circuit for controlling the switch circuit, and a control voltage generating circuit that generates a first control voltage when the switch circuit is cut off. The control circuit controls the switch circuit in accordance with the first control voltage. The control voltage generating circuit further generates a second control voltage when the switch circuit is conductive, and then the control circuit controls the switch circuit in accordance with the second control voltage.

Abstract: An electronic apparatus capable of saving power is provided. The electronic apparatus includes a buffer, a central processing unit (CPU), and a power supply unit. The power supply unit includes a mechanical switch circuit, a first switch circuit, and a second switch circuit. The first switch circuit is capable of being turned on by the mechanical switch circuit to receive power from a power input port and providing power to the buffer. The second switch circuit is capable of being turned on by the mechanical switch circuit to receive power from the power input port through the first switch circuit and providing power to the CPU, and the CPU being operable to generate a control signal to turn off the second switch circuit to interrupt the power provided to the CPU.

Abstract: An under-voltage protection circuit has a power input terminal connected to a battery, a power output terminal connected to an electronic device, a switch circuit for switching the power supply circuit from the power input terminal to the power output terminal, a control circuit for controlling the switch circuit, and a control voltage generating circuit that generates a first control voltage when the switch circuit is cut off. The control circuit controls the switch circuit in accordance with the first control voltage. The control voltage generating circuit further generates a second control voltage when the switch circuit is conductive, and then the control circuit controls the switch circuit in accordance with the second control voltage.

Abstract: A battery management system includes a power converter, a first switch, a second switch, a first detecting unit, and a CPU. The power converter is configured to divide current provided by the power supply into a first and a second output current, according to a working current of a system load in a normal state, the first output current is used to power the system load, and the second output current is used to charge a battery unit. The CPU is configured to determine whether the value of current detected by the first detecting unit is greater than a threshold value, and further controls turning on the first switch to power the system load using the first output current, and turn on the second switch to charge the battery unit using the second output current.

Abstract: A protection circuit for protecting a rechargeable battery is provided. The protection circuit includes a voltage-threshold generating unit and a comparing unit. The voltage-threshold generating unit is for generating a threshold voltage. The comparing unit is for comparing the threshold voltage to the rechargeable battery voltage and outputting a charging enable signal or a charging disable signal according to the comparison result. The comparing unit outputs the charging enable signal if the amplitude of the threshold voltage is lower than that of the rechargeable battery, or outputs the charging disable signal as the amplitude of the threshold voltage is equal to or higher than that of the rechargeable battery. A battery charger apparatus using the protection circuit is also provided.

Abstract: An electronic apparatus capable of saving power is provided. The electronic apparatus includes a buffer, a central processing unit (CPU), and a power supply unit. The power supply unit includes a mechanical switch circuit, a first switch circuit, and a second switch circuit. The first switch circuit is capable of being turned on by the mechanical switch circuit to receive power from a power input port and providing power to the buffer. The second switch circuit is capable of being turned on by the mechanical switch circuit to receive power from the power input port through the first switch circuit and providing power to the CPU, and the CPU being operable to generate a control signal to turn off the second switch circuit to interrupt the power provided to the CPU.

Abstract: An electronic device, includes a USB interface, a processing unit, a master-slave select triggering circuit, a controlling unit, a selection circuit and a switching circuit. The master-slave selection triggering circuit including an input port, a first output port and a second output port. The master-slave select triggering circuit is used to detect the type of external electronic devices connected to the USB interface, if the external electronic device is a master device, the first and second output port output a slave triggering signal, the controlling unit switches off the switching circuit t and the selection circuit selects the processing unit into slave mode; if the external electronic device is the slave device, the first and second output port output a master triggering signal, the controlling unit switches on the switching circuit and the selection circuit select the processing unit into master mode.

Abstract: An electronic device, includes a USB interface, a processing unit, a master-slave select triggering circuit, a controlling unit, a selection circuit and a switching circuit. The master-slave selection triggering circuit including an input port, a first output port and a second output port. The master-slave select triggering circuit is used to detect the type of external electronic devices connected to the USB interface, if the external electronic device is a master device, the first and second output port output a slave triggering signal, the controlling unit switches off the switching circuit t and the selection circuit selects the processing unit into slave mode; if the external electronic device is the slave device, the first and second output port output a master triggering signal, the controlling unit switches on the switching circuit and the selection circuit select the processing unit into master mode.