PSUfanspeedcontrol.ppt

,Klepnutm lze upravit styly pedlohy textu.,Druh rove,Tet rove,tvrt rove,Pt rove,Global Fulfillment Operations,*,PSU Fan Curve Feasibility Evaluation,Foxconn Confidential,Thermal team,2010/7/8,Foxconn Confidential,PSU Fan Control Circuit,PSU,風,扇轉速,控制,原理,:,1.,熱,敏電阻的位置在,PSU,內部的散熱器,上,，熱敏電阻的阻抗將隨著散熱器溫度的上升而下降，它將導致比較器的反相輸入端（負端）的電壓上升，通過比較器及後面的電路來控制風扇的輸入電壓來達到控制風扇的轉速,。,2.,熱敏電阻的阻抗跟散熱器的溫度成反比，而散熱器的溫度與,12V,和,5V,電壓的,Loading,成正比。所以散熱器的溫度會直接通過控制電路控制風扇的轉速。即,Ts=,ca,Power,+Ta,，,Ts,為熱敏電阻偵測到的溫度，,ca,為散熱器的熱阻值，,Power,為,12V,和,5V,電壓輸出的功率，,Ta,為散熱器的環境溫度。,Foxconn Confidential,PSU Fan Speed Control Formula,Per (T,sensor,-T,a,)/P=,ca,，,T,sensor,=,ca,*P+T,a,T,sensor,-PSU heatsink,上的熱敏電阻的溫度,T,a,-PSU heatsink,周圍的環境的溫度,ca,-PSU heatsink,的熱阻,P-PSU power consumption,T,sensor,P,Ta,T,sensor,=,ca,*P+T,a,Foxconn Confidential,PSU Fan Curve Feasibility Evaluation,Item,PSU Input(W),PSU Inlet Temperature(,),PSU,Tsensor,(,),Idle25,118,34.0,35.7,3DMark25,254,38.0,46.1,TDP25,247,36.6,44.2,3DMark35,270,46.5,55.8,TDP35,260,45.9,55.5,35.7,44.2,46.1,55.5,55.8,25CIdle,：,1000rpm,（,Acoustic limitation,）,25C 3Dmark,：,1350rpm,（,Acoustic limitation,）,Per calculation,，,35C 3Dmark PSU,Fan speed should be 1676,35C TDP PSU fan speed should be 1666rpm,總結：,1.,首先評估出系統,Acoustic,的在不同的測試條件下風扇的限制轉速。再驗證相同條件下的,PSU,的,Fan Curve,是否能滿足要求。如不能滿足要求，求出,PSU,風扇合理的轉速。,2.,根據以上兩條求出系統各風扇的合理的轉速評估系統的散熱是否合理，及系統的,Fan,Curve,是否合理。,