W83791G Datasheet, PDF (30/99 Pages) Winbond – Winbond H/W Monitoring IC

W83791D/G
6.7.3.2. Fan Speed Cruise mode
At this mode, W83791D/G provides the Smart Fan system to automatically control the fan speed
within a 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.
A
Count
C
170
160
150
PWM ¹⁰⁰
Duty
Cycle ⁵⁰
0
Figure 10-3
Of course, Smart Fan control system can be disabled and the fan speed control algorithm can be
programmed by BIOS or application software.
6.8 Temperature Measurement Machine
The temperature data format is 8-bit two-complement for sensor 1 and 9-bit two-complement for
sensor 2/3. The 8-bit temperature data can be obtained by reading the CR [27h]. The 9-bit
temperature data can be obtained by reading the 8 MSBs from the bank0 CR [C0/ C8h] and the LSB
from the bank0 CR [C1/C9h] bit 7. The format of the temperature data is show in Table 3.
TEMPERATURE
+125°C
+25°C
+1°C
+0.5°C
+0°C
-0.5°C
-1°C
-25°C
-55°C
8-BIT DIGITAL OUTPUT
8-Bit Binary
8-Bit Hex
0111,1101
7Dh
0001,1001
19h
0000,0001
01h
-
-
0000,0000
00h
-
-
1111,1111
FFh
1110,0111
E7h
1100,1001
C9h
9-BIT DIGITAL OUTPUT
9-Bit Binary
9-Bit Hex
0,1111,1010
0FAh
0,0011,0010
032h
0,0000,0010
002h
0,0000,0001
001h
0,0000,0000
000h
1,1111,1111
1FFh
1,1111,1110
1FFh
1,1100,1110
1CEh
1,1001,0010
192h
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Publication Release Date: April 14, 2006
Revision 1.1