Acoustic Fan Speed Control
R
58
Thermal/Mechanical Design Guide
Figure 20. Temperature Range = 10 °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
It should be noted that having T
DIODE
above T
CONTROL
is expected for near TDP power levels and
high system ambient. See Section 6.5 for additional discussion on T
CONTROL
versus Thermal
Profile.
For use with the Intel
®
Boxed Pentium 4 Processor in 775–Land LGA Package on the enabled
reference solution, a T
RANGE
value of 10 °C is recommended for ATX chassis.
6.3.1.2
Minimum PWM Duty Cycle
The final step in determining the FSC setting is to determine the minimum PWM Duty cycle. This
is the fan speed for any T
DIODE
< T
LOW
. The selection of this value is dependent on:
•
Acoustic target at system idle
•
Voltage regulator cooling
For a motherboard design intending to use the Intel Boxed Pentium 4 Processor in 775–land LGA
Package or the enabled reference thermal solution the recommended minimum PWM duty cycle
is 30%.
Summary of Contents for 640 - Pentium 4 640 3.2GHz 800MHz 2MB Socket 775 CPU
Page 14: ...Introduction R 14 Thermal Mechanical Design Guide ...
Page 38: ...Thermal Management Logic and Thermal Monitor Feature R 38 Thermal Mechanical Design Guide ...
Page 52: ...Intel Thermal Mechanical Reference Design Information R 52 Thermal Mechanical Design Guide ...
Page 60: ...Acoustic Fan Speed Control R 60 Thermal Mechanical Design Guide ...
Page 72: ...Heatsink Clip Load Metrology R 72 Thermal Mechanical Design Guide ...
Page 99: ...Mechanical Drawings R Thermal Mechanical Design Guide 99 Figure 50 Reference Fastener Sheet 1 ...
Page 103: ...Mechanical Drawings R Thermal Mechanical Design Guide 103 Figure 54 Clip Heatsink Assembly ...
