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Sensor Based Thermal Specification Design Guidance
Figure 5-5.
Thermal Solution Performance vs. Fan Speed
Note:
This data is taken from the validation of the RCBF5 reference processor thermal
solution. The Ψ
5.4
Fan Speed Control (FSC) Design Process
The next step is to incorporate the thermal solution characterization data into the
algorithms for the device controlling the fans.
As a reminder, the requirements are:
• When the DTS value is at or below T
with prior processors.
• When DTS is above T
vs. RPM to achieve the necessary level of cooling.
Ψ
CA
This chapter discusses two implementations. The first is a FSC system that is not
provided the T
current T
acoustic benefit by operating the processor closer to the thermal profile. But only the
T
AMBIENT
performance.
In the development of the FSC algorithm it should be noted that the T
expected to change at significantly slower rate than the DTS value. The DTS value will
be driven by the workload on the processor and the thermal solution will be required to
respond to this much more rapidly than the changes in T
An additional consideration in establishing the fan speed curves is to account for the
thermal interface material performance degradation over time.
Thermal/Mechanical Design Guide
0.50
0.40
0.30
0.20
0.10
0.00
600
1100
Psi-ca
vs. RPM data is available in
CA
CONTROL
information and a FSC system that is provided data on the
AMBIENT
. Either method will result in a thermally compliant solution and some
AMBIENT
aware FSC system can fully use the specification for optimized acoustic
1600
2100
2600
RPM
System (BA)
Table 5-1
, the fans can be slowed down; just as
CONTROL
, FSC algorithms will use knowledge of T
5.9
5.4
4.9
4.4
3.9
3.4
2.9
2.4
1.9
3100
3600
at the end of this chapter.
AMBIENT
is
AMBIENT
.
AMBIENT
and
33
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