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Thermal Metrology
Thermal and Mechanical Design Guidelines 29
Figure 10 illustrates the combination of the different thermal characterization
parameters.
Figure 10. Processor Thermal Characterization Parameter Relationships
3.1.1 Example
The cooling performance, Ψ
JA,
is then defined using the principle of thermal
characterization parameter described above:
• The junction temperature
TJ-MAX
and thermal design power TDP given in the
processor datasheet.
• Define the allowable heatsink temperature for processor, T
S-TOP-MAX
.
The following provides an illustration of how one might determine the appropriate not
related to any specific Intel processor thermal specifications, and are for illustrative
purposes only.
Assume the TDP, as listed in the datasheet, is 20 W and the maximum junction
temperature 20 W is 90 °C. Assume as well that the system airflow has been
designed such that the local ambient temperature is 42 °C, and Ψ
HS_BASE
= 0.3
°
C/W.
Then the following could be calculated using
Equation 2:
Ψ
JA
= (T
J
– T
A
) / TDP = (90 – 55) / 20 = 1.75 °C/W
T
S-TOP
TIM
T
J
Ψ
JS
Ψ
HS BASE
Ψ
S
-
TOP
-
A
T
A