Fan controlling circuit

A fan controlling circuit is provided. The fan controlling circuit includes an integral unit, an operational amplifier, a PMOS transistor, and an NMOS transistor. The integral unit transforms pulse width modulation (PWM) signals to voltages, and transmits the voltages to positive and negative input...

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Bibliographic Details
Main Authors Ko, Tin-Chen, Huang, Po-Hsueh
Format Patent
LanguageEnglish
Published 11.12.2012
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Summary:A fan controlling circuit is provided. The fan controlling circuit includes an integral unit, an operational amplifier, a PMOS transistor, and an NMOS transistor. The integral unit transforms pulse width modulation (PWM) signals to voltages, and transmits the voltages to positive and negative input terminals of the operational amplifier. The PMOS transistor is coupled between a first PWM signal and an output terminal, and a gate of the PMOS transistor is coupled to an output of the operational amplifier. The NMOS transistor is coupled between a second PWM signal and the output terminal, and a gate of the NMOS transistor is coupled to the output of the operational amplifier. The fan controlling circuit may be formed by discrete elements and use a same voltage source as fans, so that the design cost and complexity are reduced.