Constant speed control circuit for a fan
OwnerHsin-Mao Hsiehinventor
Life of this patent
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Abstract
A constant speed control circuit for a fan includes a timing control unit, a driving unit and a fan speed control (FSC) unit. The fan speed control unit receives an external frequency signal from a frequency generator, which represents an expected rotational speed of the fan. Based on the external frequency signal, the FSC unit generates an adjusting signal that is input to the timing control unit. After the timing control unit compares a Hall signal with the adjusting signal, driving signals are generated and provided to control the activation time of transistors of the driving unit. Thereby, the fan is operated at a constant speed status.
Claims9
A constant speed control circuit for a fan comprising:
- a timing control unit receiving a Hall signal from a Hall element that is used for detecting a rotational speed of the fan;
- a driving unit connected to the timing control unit and driving the fan to rotate;
- a fan speed control unit connected to the timing control unit and receiving an external reference signal, wherein an adjusting signal in the form of a pulse width modulation (PWM) signal is generated based on the external reference signal, and then the PWM signal is input to the timing control unit;
- wherein the timing control unit compares the Hall signal with the adjusting signal to generate a driving signal for the driving circuit thereby controlling the fan to be operated at a constant speed.
Dependencies are inferred from the claim text.