W83791D Information Storage Devices, Inc, W83791D Datasheet - Page 31

• Manufacturer Part Number: W83791D
• Description: Hardware Monitor With Speech Synthesizer And Asf Functions
• Manufacturer: Information Storage Devices, Inc

6.7.3.2
specific range. In the beginning, a wanted fan speed count and interval must be set (ex. 160 10 ) by BIOS. As long
as the fan speed count remains in the specific range, PWM duty cycle will keep the current value. If current fan
speed count is higher than the high limit (ex. 160+10), PWM duty cycle will be increased to make the count under
the high limit. On the other hand, if current fan speed count is less than the low limit(ex. 160-10), PWM duty cycle
will be decreased to make the count higher than the low limit. See Figure 10-3 example.
BIOS or application software.
Of course, Smart Fan control system can be disabled and the fan speed control algorithm can be programmed by
At this mode, W83791D provides the Smart Fan system to automatically control the fan speed within a
PWM
Duty
Cycle
58`C
55`C
52`C
Count
100
50
PWM
Duty
Cycle
0
Fan Speed Cruise mode
170
160
150
Fan Start = 20%
100
50
A
0
A
Fan Stop = 10%
Figure 10-2.
Figure 10-3.
24
C
B
C
Fan Start = 20%
Publication Release Date: Aug, 2001
D
W83791D
Preliminary
Revision 0.41