Legacy Fan Speed Control
102
Thermal and Mechanical Design Guidelines
Figure 61. 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
SENSOR
above T
CONTROL
is expected for workloads near
TDP power levels and high system ambient. See Section
E.4 for additional discussion
on T
CONTROL
versus Thermal Profile
For use with the ATX Boxed Processor enabled reference solution a T
RANGE
value of
10°C is recommended. For BTX Boxed Processor enabled reference solutions T
RANGE
value of 7 °C is recommended.
E.2.1.2
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
SENSOR
< 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 Boxed Processor or the enabled
reference thermal solution the recommended minimum PWM duty cycle is 20%.
Note:
Set minimum PWM Duty Cycle only as low as required to meet acoustic requirements.
The FSC design needs to accommodate transition from a low power state to TDP
workloads without having PROCHOT# becoming active.
Содержание QX68000 Core 2 Extreme
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Страница 112: ...BTX System Thermal Considerations 112 Thermal and Mechanical Design Guidelines...
