Abstract: A device which includes interfaces, a measurement unit, a switching unit, and a control unit is used to parcel out charging currents to other chargeable devices, and allow partial charging of certain devices when full power is not available. The interfaces are connected to the chargeable devices. The measurement unit is connected to the power supply unit and the interfaces, and obtains a maximum supply current of the power supply unit and charging currents for the chargeable devices. The switching unit is connected between the measurement unit and the interfaces. The control unit is connected to the measurement unit and the switching unit, and selectively allows charging of the chargeable devices by controlling the switching unit according to the maximum supply current and the charging currents required.

Abstract: A device which includes interfaces, a measurement unit, a switching unit, and a control unit is used to parcel out charging currents to other chargeable devices, and allow partial charging of certain devices when full power is not available. The interfaces are connected to the chargeable devices. The measurement unit is connected to the power supply unit and the interfaces, and obtains a maximum supply current of the power supply unit and charging currents for the chargeable devices. The switching unit is connected between the measurement unit and the interfaces. The control unit is connected to the measurement unit and the switching unit, and selectively allows charging of the chargeable devices by controlling the switching unit according to the maximum supply current and the charging currents required.

Abstract: A power level identification circuit includes a power interface, a voltage conversion unit, a waveform detection unit, a signal pre-processing unit and a processing unit. The power interface receives electrical power and first signals indicating a level of the power. The voltage conversion unit receives the power from the power interface and converts the power. The waveform detection unit filters the power and obtains the first signals indicating power level. The signal pre-processing unit shapes the waveform of the first signals indicating power level and thereby generates second signals indicating power level. The processing unit identifies a level of the second signals indicating power level and switches to one of modes of the power level identification circuit corresponding to the identified level of the second signals indicating power level. A power level flag circuit and a power level supply system are also provided.

Abstract: A power level identification circuit includes a power interface, a voltage conversion unit, a waveform detection unit, a signal pre-processing unit and a processing unit. The power interface receives electrical power and first signals indicating a level of the power. The voltage conversion unit receives the power from the power interface and converts the power. The waveform detection unit filters the power and obtains the first signals indicating power level. The signal pre-processing unit shapes the waveform of the first signals indicating power level and thereby generates second signals indicating power level. The processing unit identifies a level of the second signals indicating power level and switches to one of modes of the power level identification circuit corresponding to the identified level of the second signals indicating power level. A power level flag circuit and a power level supply system are also provided.

Abstract: A fan speed control circuit is provided. The circuit includes a control chip. The control chip stores a relationship table recording a number of duty cycle intervals and a number of rotational speeds of a fan. Each duty cycle interval corresponds to one rotational speed of the fan. The control chip obtains a preset number of PWM signals outputted by a processing chip; determines the average value according to the duty cycle of the obtained preset number of PWM signals; determines which duty cycle interval the average value is in, according to the relationship table; determines the rotational speed of the fan corresponding to the determined duty cycle interval according to the relationship table; and controls the fan to rotate according to the determined rotational speed.

Abstract: A fan speed control circuit is provided. The circuit includes a control chip. The control chip stores a relationship table recording a number of duty cycle intervals and a number of rotational speeds of a fan. Each duty cycle interval corresponds to one rotational speed of the fan. The control chip obtains a preset number of PWM signals outputted by a processing chip; determines the average value according to the duty cycle of the obtained preset number of PWM signals; determines which duty cycle interval the average value is in, according to the relationship table; determines the rotational speed of the fan corresponding to the determined duty cycle interval according to the relationship table; and controls the fan to rotate according to the determined rotational speed.

Abstract: An electronic device assigns power to USB ports dynamically. A total current detection circuit transmits driving voltage signals to the USB ports, and detects whether a total current provided to the USB ports exceeds a rated total current and output a total current detection signal. A plurality of short-circuit detection circuits detects whether USB devices connected to the corresponding USB ports are shorted and to output a short-circuit detection signal. A plurality of relay circuits switch connection between the USB ports and the power circuit. A USB controller outputs a control signal according to the total current detection signal and the short-circuit detection signal and directs the relay circuits to switch connection between the corresponding USB ports and the power circuit on and off.

Abstract: An electronic device assigns power to USB ports dynamically. A total current detection circuit transmits driving voltage signals to the USB ports, and detects whether a total current provided to the USB ports exceeds a rated total current and output a total current detection signal. A plurality of short-circuit detection circuits detects whether USB devices connected to the corresponding USB ports are shorted and to output a short-circuit detection signal. A plurality of relay circuits switch connection between the USB ports and the power circuit. A USB controller outputs a control signal according to the total current detection signal and the short-circuit detection signal and directs the relay circuits to switch connection between the corresponding USB ports and the power circuit on and off.