w83637hg Winbond Electronics Corp America, w83637hg Datasheet - Page 37

• Manufacturer Part Number: w83637hg
• Description: Winbond Lpc I/o Lpc I/o
• Manufacturer: Winbond Electronics Corp America

6.5 Smart Fan Control
Smart Fan Control provides two mechanisms. One is Thermal Cruise mode and the other is Fan
Speed Cruise mode.
6.5.1 Thermal Cruise mode
There are maximum 3 pairs of Temperature/FanPWM control at this mode: SYSTIN with FANPWM1,
CPUTIN with FANPWM2, VTIN with FANPWM3. At this mode, W83637HF provides the Smart Fan
system which can control the fan speed automatically depend on current temperature to keep it with in
a specific range. At first a wanted temperature and interval must be set (ex. 55 °C ±3 °C) by BIOS, as
long as the real temperature remains below the setting value, the fan will be off. Once the temperature
exceeds the setting high limit temperature (58°C), the fan will be turned on with a specific speed set by
BIOS (ex: 80% duty cycle) and automatically controlled its PWM duty cycle with the temperature
varying. Three conditions may occur:
(1) If the temperature still exceeds the high limit (ex: 58°C), PWM duty cycle will increase slowly. If the
fan has been operating in its fully speed but the temperature still exceeds the high limit(ex: 58°C), a
warning message will be issued to protect the system.
(2) If the temperature goes below the high limit (ex: 58°C), but above the low limit (ex: 52°C), the fan
speed will be fixed at the current speed because the temperature is in the target area(ex: 52 °C ~
58°C).
(3) If the temperature goes below the low limit (ex: 52°C), PWM duty cycle will decrease slowly to 0
until the temperature exceeds the low limit.
Figure 6.6 and 6.7 give the illustration for Thermal Cruise Mode.
Target Temperature
Tolerance
Tolerance
PWM
Duty
Cycle
58`C
55`C
52`C
100
50
0
Figure 6.6
Fan Start = 20%
A
- 32 -
B
Publication Release Date: March, 2006
C
D
W83637HF/HG
Revision 1.6