W83637HF Datasheet, PDF (38/149 Pages) Winbond – LPC I/O

W83637HF
A
Tolerance
58`C
Target Temperature
Tolerance
55`C
52`C
D
B
C
PWM ^{100 Fan Start = 20%}
Duty
Cycle
50
0
Fan Stop = 10%
Fan Start = 20%
Figure 6.7
One more protection is provided that duty cycle will not be decreased to 0 in the above (3) situation in
order to keep the fans running with a minimum speed. By setting CR[12h] bit3-5 to 1, FAN PWM duty
cycle will be decreased to the “Stop Duty Cycle” which are defined at CR[08h],CR[09h] and CR[17h].
6.5.2 Fan Speed Cruise mode
There are 3 pairs of FanSpeed/FanPWM control at this mode: FANIN1 with FANPWM1, FANIN2 with
FANPWM2, FANIN3 with FANPWM3.At this mode, W83637HF provides the Smart Fan system which
can control the fan speed automatically depend on current fan spesed 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 6.8 example.
A
Count
170
160
150
PWM ¹⁰⁰
Duty
Cycle ⁵⁰
0
C
Figure 6.8
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Publication Release Date: June 25, 2003
Revision 1.3