Abstract: A fan rotation speed control circuit of a power supply system is provided, which is applicable for controlling the rotation speed of the fan according to a loading state outputted by the power supply system. The fan rotation speed control circuit of the power supply system includes a waveform generating module, for generating an oscillating waveform signal; a current retrieving module, for retrieving a current signal corresponding to the loading state; a rotation speed control signal generating module, for comparing the oscillating waveform signal with the current signal, and generating a rotation speed control signal; a signal amplifying module, for amplifying an amplitude of the rotation speed control signal and outputting the amplified rotation speed control signal to the fan, so as to control the rotation speed of the fan.

Abstract: A power regulator with a constant-voltage output is provided, which includes a voltage regulator module and a voltage buffer module, wherein the voltage regulator module is spaced from a load by the voltage buffer module, so that an output voltage of the voltage regulator module is not affected by the current of the load, thereby enhancing the output precision of the power regulator.

Abstract: A hysteresis circuit applied to a comparator and an amplifier circuit thereof are provided. A hysteresis circuit is disposed on a positive feedback path of the comparator, such that the comparator resists noise interferences, and the hysteresis circuit has a feature of not affecting the feedback voltage signal, thereby making the hysteresis range of the comparator be more precise.

Abstract: A fan rotation speed control circuit of a power supply system is provided, which is applicable for controlling the rotation speed of the fan according to a loading state outputted by the power supply system. The fan rotation speed control circuit of the power supply system includes a waveform generating module, for generating an oscillating waveform signal; a current retrieving module, for retrieving a current signal corresponding to the loading state; a rotation speed control signal generating module, for comparing the oscillating waveform signal with the current signal, and generating a rotation speed control signal; a signal amplifying module, for amplifying an amplitude of the rotation speed control signal and outputting the amplified rotation speed control signal to the fan, so as to control the rotation speed of the fan.

Abstract: A power regulator with a constant-voltage output is provided, which includes a voltage regulator module and a voltage buffer module, wherein the voltage regulator module is spaced from a load by the voltage buffer module, so that an output voltage of the voltage regulator module is not affected by the current of the load, thereby enhancing the output precision of the power regulator.