Abstract: A power protection device includes a power source switching unit for shutting off the power supply from an AC power source according to an open control signal, a surge voltage protecting unit for outputting the open control signal when a surge voltage occurs, a leakage current protecting unit for outputting the open control signal when a leakage current occurs, and an over-current protecting unit for outputting an open control signal according to a current value when an over-current occurs. The power protection device provides the surge voltage protection, the leakage current protection and the over current protection at the same time.

Abstract: A motor drive circuit and method with frequency setting and correcting functions. The drive circuit includes a speed control device, which simultaneously receives a sense signal and a rotation frequency signal. A pulse width modulation signal capable of modulating a duty ratio may be generated by a pulse width modulation method. The pulse width modulation signal is then transferred to a drive timing controller that generates a timing control signal to control output timing of a power drive signal for the drive circuit. Meanwhile, a sensor is used to detect a motor and to generate a correction sense signal, which is immediately fed back to the speed control device to form a closed loop control, so that the rotation frequency of the motor may be automatically corrected and set.

Abstract: A system for controlling the rotational speed of a fan, according to a reference clock having a reference frequency, is disclosed. The rotational speed corresponds to a fan rotational speed signal. The fan rotational speed controlling unit compares the reference clock with the fan rotational speed signal, to output a speed controlling signal. The Voltage generating circuit generates a level signal corresponding to the speed controlling signal. The driving unit generates a driving signal to control the rotational speed of the fan according to the level signal. When the fan is assembled with the controlling system, only coils with the same number of turns need to be use to obtain various rated rotational speeds of fans of different specifications by altering the reference frequency of the controlling system. Because coils with different number of turns are not required in stock at the same time, the time cost and the manufacturing cost can be reduced.

Abstract: An input power control device for controlling the electrical power fed into the driven device from the power supply is provided. The power control device includes a driving device, a voltage detector, a current detector, a multiplier, and a power controller. The voltage detector detects the output voltage of the power supply, while the current detector detects the drive current fed into the driven device from the driving device. The multiplier multiplies the voltage signal and the current signal together to obtain the present electrical power input to the driven device. If the present input power of the driven device is too high, the power controller outputs an adjustment signal to the driving device to decrease the drive current of the driven device until the input power is equal to the rated value.

Abstract: A motor drive circuit and method with frequency setting and correcting functions. The drive circuit includes a speed control device, which simultaneously receives a sense signal and a rotation frequency signal. A pulse width modulation signal capable of modulating a duty ratio may be generated by a pulse width modulation method. The pulse width modulation signal is then transferred to a drive timing controller that generates a timing control signal to control output timing of a power drive signal for the drive circuit. Meanwhile, a sensor is used to detect a motor and to generate a correction sense signal, which is immediately fed back to the speed control device to form a closed loop control, so that the rotation frequency of the motor may be automatically corrected and set.

Abstract: A power source protecting device comprises a power source switching unit for shutting off the power supply from an AC power source according to an open control signal, a surge voltage protecting unit for outputting the open control signal when a surge voltage occurs, a leakage current protecting unit for outputting the open control signal when a leakage current occurs, and an over-current protecting unit for outputting the open control signal according to a current value when an over-current occurs. The present invention can provides the surge voltage protection, the leakage current protection and the over current protection at the same time. In comparison with the conventional power source protecting device, the invention can provide a more compact and low cost device, and is able to provide an accurate and safe protection according to the current detection based on an energy.

Abstract: A system for controlling the rotational speed of a fan, according to a reference clock having a reference frequency, is disclosed. The rotational speed corresponds to a fan rotational speed signal. The fan rotational speed controlling unit compares the reference clock with the fan rotational speed signal, to output a speed controlling signal. The voltage generating circuit generates a level signal corresponding to the speed controlling signal. The driving unit generates a driving signal to control the rotational speed of the fan according to the level signal. When the fan is assembled with the controlling system, only coils with the same turns need to be use to obtain various rated rotational speeds of fans of different specifications by altering the reference frequency of the controlling system. Because coils with different turns are not required in stock at the same time, the time cost and the manufacturing cost can be reduced.