W83791G Nuvoton Technology Corporation of America, W83791G Datasheet - Page 30

• Manufacturer Part Number: W83791G
• Description: IC MONITOR H/W 48-LQFP
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W83791G

• Function: Hardware Monitor
• Topology: ADC
• Sensor Type: External
• Sensing Temperature: External Sensor
• Output Type: I²C™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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.
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
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.
+125°C
+25°C
+1°C
+0.5°C
+0°C
-0.5°C
-1°C
-25°C
-55°C
TEMPERATURE
Temperature Measurement Machine
Count
PWM
Duty
Cycle
170
160
150
8-Bit Binary
0111,1101
0001,1001
0000,0001
-
0000,0000
-
1111,1111
1110,0111
1100,1001
100
50
0
8-BIT DIGITAL OUTPUT
A
8-Bit Hex
7Dh
19h
01h
-
00h
-
FFh
E7h
C9h
Figure 10-3
- 24 -
C
9-Bit Binary
0,1111,1010
0,0011,0010
0,0000,0010
0,0000,0001
0,0000,0000
1,1111,1111
1,1111,1110
1,1100,1110
1,1001,0010
Publication Release Date: April 14, 2006
9-BIT DIGITAL OUTPUT
W83791D/G
9-Bit Hex
0FAh
032h
002h
001h
000h
1FFh
1FFh
1CEh
192h
Revision 1.1