Intel Xeon processor LV Thermal Design Guide

Thermal Solution Requirements
Dual-Core Intel
®
Xeon
®
processor LV and ULV
Thermal Design Guide August 2006
22 Reference Number: 311374-002
If the local processor ambient temperature is relaxed to 35 °C, the same calculation
can be carried out to determine the new case-to-ambient thermal resistance:
It is evident from the above calculations that a reduction in the local ambient
temperature has a significant effect on the junction-to-ambient thermal resistance
requirement. This effect can contribute to a more reasonable thermal solution including
reduced cost, heatsink size, heatsink weight, and a lower system airflow rate.
Table 3 summarizes the thermal budget required to adequately cool the processors.
Since the results are based on air data at sea level, a correction factor would be
required to estimate the thermal performance at other altitudes.
W
C
T
D
P
TT
LAJ
JA
o
09.2
31
35100
=
−
=
−
=Ψ
Table 3. Required Heatsink Thermal Performance (Ψ
JA
)
Device Ψ
JA
(°C/W) at T
LA
= 40 °C at 55 °C
15 W Dual-Core Intel
®
Xeon
®
processor ULV
4.00 3.00
31 W Dual-Core Intel
®
Xeon
®
processor LV
1.94 1.45
Notes:
1. T
LA
is defined as the local (internal) ambient temperature measured approximately 1” upstream from
the device.
2.
Ψ
JA
is determined by (T
JUNCTION
- T
LA
)/TDP, so this value will change if any parameter changes.