Legacy Fan Speed Control
Thermal and Mechanical Design Guidelines
113
Figure
7-41. Temperature Range = 5 °C
0
500
1000
1500
2000
2500
3000
3500
Time (s)
RP
M
40
45
50
55
60
65
70
75
80
T
d
io
d
e
(
C
)
Fan RPM
Tdiode
Tcontrol
Tlow
An alternate would be to consider a slightly larger value such as
T
RANGE
= 10 °C. In
this case the design is trading off the acoustic margin for thermal margin.
•
There is increased granularity in the fan speeds.
•
Fan speed oscillation are significantly reduced
•
Maximum fan speed is lower
The rate of change of
Ψ
CA
vs. RPM is an exponential curve with a larger decrease at
the beginning of the fan acceleration than as the maximum speed is approached. By
having the fan start to accelerate at a lower T
SENSOR
reading the thermal solution can
keep up with rate of change in processor power. The rate of change in acoustics (dBA)
is more linear with RPM. When comparing these two metrics the choice of a larger
T
RANGE
value becomes a more acceptable trade off. Figure
the same conditions as in Figure
RANGE
= 10 °C.
Summary of Contents for Celeron Dual-Core E1000 Series
Page 10: ...10 Thermal and Mechanical Design Guidelines...
Page 26: ...Processor Thermal Mechanical Information 26 Thermal and Mechanical Design Guidelines...
Page 68: ...ATX Thermal Mechanical Design Information 68 Thermal and Mechanical Design Guidelines...
Page 86: ...Heatsink Clip Load Metrology 86 Thermal and Mechanical Design Guidelines...
Page 88: ...Thermal Interface Management 88 Thermal and Mechanical Design Guidelines...
Page 120: ...Legacy Fan Speed Control 120 Thermal and Mechanical Design Guidelines...
Page 126: ...Fan Performance for Reference Design 126 Thermal and Mechanical Design Guidelines...
Page 127: ...Fan Performance for Reference Design Thermal and Mechanical Design Guidelines 127...
