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PENTIUM® PRO PROCESSOR AT 150, 166, 180, and 200 MHz
The parameters are defined by the following
relationships where Θ is measured in °C/W (See also
Figure 40.):
•
Θ
= (T
- T
) / P
CA
C
A
D
•
Θ
= Θ
+Θ
CA
CS
SA
Where:
•
Θ
= Case-to-Ambient thermal resistance
CA
•
Θ
= Case-to-Sink thermal resistance
CS
•
Θ
= Sink-to-Ambient thermal resistance
SA
•
T
= Case temperature at defined location (°C)
C
•
T
= Ambient temperature (°C)
A
•
P
= Device power dissipation (W)
D
Airflow (LFM):
2
With 0.5" Heat Sink
With 1.0" Heat Sink
2
With 1.5" Heat Sink
2
With 2.0" Heat Sink
2
NOTES:
1.
All data taken at sea level. For altitudes above sea level, it is recommended that a derating factor of 1°C/1000 feet be
used.
2.
Heat Sink: 2.235" square omni-directional pin, aluminum heat sink with a pin thickness of 0.085", a pin spacing of 0.13"
and a base thickness of 0.15". See Figure 41. A thin layer of thermal grease (Thermoset TC208 with thermal conductivity
of 1.2W/m-°K) was used as the interface material between the heat sink and the package.
62
Table 24. Case-To-Ambient Thermal Resistance
Θ Θ CA [°C/W] vs. Airflow [Linear Feet per Minute] and Heat Sink Height
100
200
—
3.16
2.55
1.66
1.66
1.31
1.47
1.23
Ambient Air
Heat Sink
Θ
SA
Θ
CS
Heat Spreader
Figure 40. Thermal Resistance Relationships
6.2.
Thermal Analysis
Table 24 below lists the case-to-ambient thermal
resistances of the Pentium Pro processor for
different air flow rates and heat sink heights.
400
600
2.04
1.66
1.08
0.94
0.90
0.78
0.87
0.75
E
Thermal Interface
Material
Θ
CA
Ceramic Package
1
800
1000
1.41
1.29
0.80
0.76
0.71
0.67
0.69
0.65
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