Fan Speed Control Implementation Details; Fan Speed Control Example For 95W Tdp Processor1 - Intel 2ND GENERATION CORE PROCESSOR FAMILY DESKTOP - THERMAL MECHANICAL SPECIFICATIONS AND DESIGN GUIDELINES 01-2011 Specifications

Sensor Based Thermal Specification Design Guidance
8.4.4

Fan Speed Control Implementation Details

Most fan controllers allow programming a few "temperature versus PWM" or
"temperature v.s RPM" points for fan speed control and do a linear interpolation
between the points. Using
at DTS = -1. From the thermal solution performance characteristics (RPM versus
find equivalent RPM and PWM.
table may look like for processor cooling needs. DTS 1.1 only specify the thermal
performance needed at T
as needed based on rest of the platform cooling needs.
Table 8-2. Fan Speed control example for 95W TDP processor
DTS values
DTS = -59
DTS = -39
...
...
DTS = -20
DTS = -1
Notes:
1. This table is for illustration purposes only. PWM% and RPM numbers will vary based on system thermal
solution for the required
For a typical chassis that has Trise lower than 10C, based on the reference thermal
solution data, a fan speed of 1050 RPM will give the needed 
maximum fan speed of 3150 RPM will be programmed for DTS = -1. As the processor
workload continues to increase the DTS value will increase and the FSC algorithm will
linearly increase the fan speed from the 1050 RPM at DTS = -20 to fans full speed at
DTS = -1.
Figure 8-9
options including DTS 1.1.
In this example the following assumptions are made:
• Operating T
• Thermal Solution designed / validated to a 40 °C ambient max as used in the
example in
(DHA-A))
• T
CONTROL
• For DTS 1.0 the FSC device has access to T
• Below T
• Power = 75W with all cores active
Thermal/Mechanical Specifications and Design Guidelines
Table 8-1
Table 8-2
and at DTS = -1. All the other points can be defined
CONTROL
Calculated Tj
(assuming
TjMax = 99C)
40C
60C
...
...
79C
98C

CA targets.
shows a comparison chart from this tool for various fan speed control
= 35 °C
AMBIENT
Section 8.4.1 Reference processor thermal solution (RCFH7-1156
= -20
the fan speed is slowed down to minimum as in prior products
CONTROL
determine the  requirements at T
CA
give an example of how a fan speed control
1

Example PWM%
CA
... 20%
... 30%
... ...
... ...
0.564 40%
0.343 100%
data
AMBIENT
and
CONTROL

CA)
Example RPM
1000
1050
...
...
1100
3150
at T . A
CA CONTROL
75