Prolific Technology Inc.

Chih-Shih Yang

Wan-Yang Chen

Jia-Jun Liu

Chia-Chang Hsu

Kung-Ching Hung

High temperature protection system includes a thermal detection and control circuit, a pulse width modulation signal output circuit, a driving circuit, and a coil module. The thermal detection and control circuit is used for detecting a temperature and outputting at least one corresponding control signal. The pulse width modulation signal output circuit is coupled to the thermal detection and control circuit for generating a pulse width modulation signal according to the at least one control signal. The driving circuit is coupled to the pulse width modulation signal for generating at least one driving voltage. The coil module is coupled to the driving circuit and is operated according to the at least one driving voltage.

High temperature protection system for adjusting duty cycle by using pulse width modulation signal

A high voltage protection system includes a high voltage processing circuit, a pulse width modulation signal outputting circuit, a driving circuit, and a coil module. The high voltage processing circuit is used for receiving and processing a high voltage. The pulse width modulation signal output circuit is coupled to the high voltage processing circuit for generating a pulse width modulation signal. The driving circuit is coupled to the pulse width modulation signal outputting circuit for receiving the pulse width modulation signal and generating a driving voltage accordingly. The coil module is coupled to the driving circuit and is operated according to the driving voltage.

High voltage protection system for adjusting duty cycle by using pulse width modulation signal

A negative voltage protection system includes a negative voltage comparison circuit, a signal processing circuit, a driving circuit, a driving output circuit, a power device, and a coil module. When the coil module generates a back electromotive force, the coil module outputs a negative voltage. When an intensity of the negative voltage detected by the negative voltage comparison circuit is greater than a predetermined value, the signal processing circuit generates a control signal to the driving circuit. The driving circuit controls the driving output circuit and the power device to reduce the intensity of the negative voltage according to the control signal.

Negative voltage protection system for reducing an intensity of negative voltage

A contactless switch provided by the present disclosure is coupled to a signal input device and receives a magnetic signal generated by a magnetic trigger mechanism. The contactless switch includes: a magnetic sensor, for sensing the magnetic signal and generating a corresponding trigger control signal; a controller, for generating a switch signal according to the trigger control signal; and a mode switch module, for processing the input signal to generate an output signal according to the switch signal.

Contactless switch and associated method

A driving circuit of a fan includes a magnetic pole sensor for generating a magnetic pole sensing signal, a first waveform generator coupled to the magnetic pole sensor for generating a first waveform according to the magnetic pole sensing signal, a second waveform generator for generating a second waveform, a comparison circuit coupled to the first waveform generator and the second waveform generator for comparing the first waveform and the second waveform for generating a third waveform, a control signal generator coupled to the comparison circuit for generating a control signal according to the third waveform and an external signal, and a current generator coupled to the magnetic pole sensor and the control signal generator for outputting current to a coil of a stator of the fan according to the magnetic pole sensing signal and the control signal.

Driving circuit of a fan

A noiseless driving circuit for direct current (DC) motor is disclosed. The driving circuit uses a magnetic-field sensing circuit with a Hall sensor to sense the corresponding position of the permanent magnet rotor. According to the corresponding position of the permanent magnet rotor, a linear circuit generates a signal with trapezoid waveform for driving the coil of the DC motor. The coils of the DC motor perform soft switching operations without resulting backing electromotive force (BEMF). Therefore, the noise during the operation of the DC motor can be substantially reduced.

Noiseless driving circuit for DC motor

A DC brushless motor operation speed control method is disclosed. First, a linearly voltage dependent current source is used to charge a capacitor and the terminal voltage of the capacitor is coupled to a linearly voltage dependent base frequency level detector. When the output voltage of the capacitor reaches the base frequency reference voltage, the signal output from the base frequency level detector will make the capacitor discharge, outputting a series of base frequency triangular waves. Under different supply voltages, all the generated base frequency triangular waves have the same cycle time. The base frequency triangular waves are transmitted to a speed control comparator. Through pulse width modulation, the speed control reference voltage adjusts the output pulse width of the comparator and thereby controls the speed of the motor.

Voltage independent PWM base frequency generating method

A method for driving a brushless DC motor is disclosed in accordance with the present invention. Firstly, a driving control signal is generated based on sensed information of a motor rotor's magnetic field distribution. The driving control signal is inactive in the case that four rotor magnetic arcs are rotated more or less than critical positions of the rotor corresponding a stator. At that time, no magnetic fields are produced from the motor's stator, and thus the rotor rotates by inertial force. In another case, the driving control signal is issued in a conventional manner.

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Hsinchu, Taiwan

Chih-Shih Yang