Intel Pentium 4 Processor on 90 nm Process Thermal and Mechanical Design Guidelines

Thermal Requirements
R
Intel
®
Pentium
®
4 on 90 nm Process Thermal Design Guide 31
Figure 8. Example Thermal Profile
30
35
40
45
50
55
60
65
70
75
30 40 50 60 70 80 90 100 110
Watts
Case Temperature (C)
Therm al Profile
FMB2
Heatsink
Design Point
3.5.2 T
CONTROL
T
CONTROL
defines the maximum operating temperature for the on-die thermal diode when the
thermal solution fan speed is being controlled by the on-die thermal diode. The T
CONTROL
parameter
defines a very specific processor operating region where the T
C
is not specified. This parameter
allows the system integrator a method to reduce the acoustic noise of the processor cooling
solution while maintaining compliance to the processor thermal specification.
The value of T
CONTROL
is driven by a number of factors. One of the most significant of these is the
processor leakage current. As a result a processor with a high T
CONTROL
will dissipate more power
than a part with lower value of T
CONTROL
when running the same application.
The value of T
CONTROL
is calculated such that regardless of the individual processor’s T
CONTROL
value,
the thermal solution should perform similarly. The higher leakage of some parts is offset by a
higher value of T
CONTROL
in such a way that they will behave virtually the same acoustically
This is achieved in part by using the
Ψ
CA
vs. RPM and RPM vs. Acoustics (dBA) performance
curves from the Intel enabled thermal solution. A thermal solution designed to meet the thermal
profile should perform virtually the same for any value of T
CONTROL
.
The value for T
CONTROL
is calculated by the system BIOS based on values read from a factory
configured processor register. The result can be use to program a fan speed control component.
See the processor datasheet for further details on calculating T
CONTROL
.