Intel E2160 Design Guide - Page 22

Intel® CoreTM 2 Duo E6400, E4300, and Intel® Pentium® Dual-Core E2160 Processor-Thermal Metrology Figure 4. ΨSA is a measure of the thermal characterization parameter from the bottom of the heatsink to the local ambient air. SA is dependent on the heatsink material, thermal conductivity, and geometry. It is also strongly dependent on the air velocity through the fins of the heatsink. Figure 4 illustrates the combination of the different thermal characterization parameters. Processor Thermal Characterization Parameter Relationships TA Heatsink TIM IHS Processor ΨCA TS TC LGA775 Socket 3.1.1 System Board Example The cooling performance, ΨCA, is then defined using the principle of thermal characterization parameter described above: • The case temperature TC-MAX and thermal design power TDP given in the processor datasheet. • Define a target local ambient temperature at the processor, TA. Since the processor thermal profile applies to all processor frequencies, it is important to identify the worst case (lowest ΨCA) for a targeted chassis characterized by TA to establish a design strategy. The following provides an illustration of how one might determine the appropriate performance targets. The example power and temperature numbers used here are not related to any specific Intel processor thermal specifications, and are for illustration purposes only. Assume the TDP, as listed in the datasheet, is 100 W and the maximum case temperature from the thermal profile for 100 W is 67° C. Assume as well that the system airflow has been designed such that the local ambient temperature is 38° C. Then the following could be calculated using Equation 1 from above: ΨCA = (TC,- TA) / TDP = (67 - 38) / 100 = 0.29 °C/W Intel® CoreTM 2 Duo E6400, E4300, and Intel® Pentium® Dual-Core E2160 Processor TDG 22 October 2007 Order Number: 315279 - 003US