Example; Processor Thermal Characterization Parameter Relationships - Intel Celeron D Thermal Design Manual

Ψ
is a measure of the thermal characterization parameter from the bottom of the heatsink to the
SA
local ambient air.
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.
Figure 4. Processor Thermal Characterization Parameter Relationships
3.1.1

Example

The cooling performance, Ψ
in the previous section:
•
The case temperature T
datasheet.
•
Define a target local ambient temperature at the processor, T
Since the processor thermal profile applies to all processor frequencies, it is important to identify
the worst case (lowest Ψ
strategy such that a given heatsink can cover a given range of processor frequencies.
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 Intel
processor thermal specifications, and are for illustrative purposes only.
Assume the datasheet TDP is 100 W and the maximum case temperature from the thermal profile
for 100W 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
To determine the required heatsink performance, a heatsink solution provider would need to
determine Ψ
heatsink solution were designed to work with a TIM material performing at Ψ
solving for
® ®
Intel Celeron D Processor in the 775-Land LGA Package Thermal Design Guide19
303730
Order #
Ψ
is dependent on the heatsink material, thermal conductivity, and geometry. It
SA
Heatsink
Heatsink
TIM
TIM
IHS
IHS
Processor Processor
is defined using the thermal characterization parameter described
CA,
and thermal design power TDP given in the processor
C-MAX
) for a targeted chassis (characterized by T
CA
Ψ
= (T – T ) / TDP = (67 – 38) / 100 = 0.29 °C/W
CA C A
performance for the selected TIM and mechanical load configuration. If the
CS
Equation 2 from above, the performance of the heatsink would be:
Ψ = Ψ – Ψ
SA CA CS
T
T
A
A
T T
S
S
T
T
C C
= 0.29 – 0.10 = 0.19 °C/W
Thermal Metrology
Ψ
Ψ
CA
CA
LGA775 Socket
LGA775 Socket
System Board
System Board
.
A
) to establish a design
A
Equation 1:
0.10 °C/W,
CS