Specifications

PENTIUM® PRO PROCESSOR AT 150, 166, 180, and 200 MHz E
62
The parameters are defined by the following
relationships where Θ is measured in °C/W (See also
Figure 40.):
• Θ
CA
= (T
C
- T
A
) / P
D
• Θ
CA
= Θ
CS
+Θ
SA
Where:
• Θ
CA
= Case-to-Ambient thermal resistance
• Θ
CS
= Case-to-Sink thermal resistance
• Θ
SA
= Sink-to-Ambient thermal resistance
• T
C
= Case temperature at defined location (°C)
• T
A
= Ambient temperature (°C)
• P
D
= Device power dissipation (W)
Ambient Air
Θ
SA
Θ
CS
Θ
CA
Heat Sink
Thermal Interface
Material
Heat Spreader
Ceramic Package
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.
Table 24. Case-To-Ambient Thermal Resistance
ΘΘ
CA
[°C/W] vs. Airflow [Linear Feet per Minute] and Heat Sink Height
1
Airflow (LFM): 100 200 400 600 800 1000
With 0.5” Heat Sink
2
— 3.16 2.04 1.66 1.41 1.29
With 1.0” Heat Sink
2
2.55 1.66 1.08 0.94 0.80 0.76
With 1.5” Heat Sink
2
1.66 1.31 0.90 0.78 0.71 0.67
With 2.0” Heat Sink
2
1.47 1.23 0.87 0.75 0.69 0.65
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.