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PC System power supply fan control with planar generated PWM Disclosure Number: IPCOM000016307D
Original Publication Date: 2002-Nov-22
Included in the Prior Art Database: 2003-Jun-21

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System acoustic levels remain high in IBM PCs even after actively controlling the fans on the processor and chassis, presently the fan in the system power supply is controlled by thermistor controlled voltage levels. This type of control limits the lowest speed the fan can rotate at approximately 50% of top speed. The system board active control of a PWM will give the ability to operate the fan at approximately 90% below max speed. This reduction in speed will allow the acoustics of the machine to be significantly lower across the entire system. The feedback for a closed loop control will be available via constant system temp monitoring with a digital thermal solution. An onboard power supply override will be available on the main switchers heat-sink such to spin the fan in an over temperature condition (Fig. 1). Fig. 1 1