W83L784R_05 Datasheet, PDF (22/52 Pages) Winbond – Monitoring IC

W83L784R/ W83L784G
A
58`C
55`C
52`C
PWM ¹⁰⁰
Duty
Cycle ⁵⁰
Fan Start = 20%
0
D
B
C
Fan Stop = 10%
Fan Start = 20%
Figure 17-2
6.5.3.2. Fan Speed Cruise mode
At this mode, W83L784R/G provides the Smart Fan system which can control the fan speed
automatically depend on current fan speed to keep it with in a specific range. A wanted fan speed
count and interval must be set (ex. 160 ± 10) by BIOS. As long as the fan speed count is the specific
range, PWM duty will keep the current value. If current fan speed count is higher than the high limit
(ex. 160+10), PWM duty will be increased to keep the count less than the high limit. Otherwise, if
current fan speed is less than the low limit (ex. 160-10), PWM duty will be decreased to keep the
count higher than the low limit. See Figure 18 example.
A
Count
C
170
160
150
PWM ¹⁰⁰
Duty
Cycle ⁵⁰
0
Figure 18
Of course, Smart Fan control system can be disabled and the fan speed control algorithm can be
programmed by BIOS or application software.
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Publication Release Date: Jan. 2005
Revision 1.1