W83791G Nuvoton Technology Corporation of America, W83791G Datasheet - Page 28

• 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

6.7.2
The W83791D/G provides five sets of PWM for fan speed control. The duty cycle of PWM can be
programmed by a 8-bit registers defined in the Bank0 CR [81], CR [83], CR [94], CR [9E] and CR [9F].
The default duty cycle is set to 100%, that is, the default 8-bit register is set to 0xFFh. The expression
of duty cycle can be represented as follows.
Figure 8-1. Fan with Tach Pull-Up to +5V
Figure 8-3. Fan with Tach Pull-Up to +12V
Connector
Connector
FAN
FAN
FAN Out
Fan speed control
FAN Out
+12V
GND
and Zener Clamp
+12V
GND
+12V
+12V
Duty
3.9V Zener
−
Pull-up resister
4.7K Ohms
Pull-up resister
+5V
Fan Input
Fan Input
cycle
> 1K
PWM Clock Input
(%)
Pin 18/19/20
Pin 18/19/20
W83791D
W83791D
=
Programmed
G
D
S
R1
NMOS
Connector
Connector
- 22 -
Figure 8-4. Fan with Tach Pull-Up to +12V, or
Figure 9.
FAN
FAN
- 8
Figure 8-2. Fan with Tach Pull-Up to +12V, or Totem-Pole
FAN Out
+12V
FAN Out
255
R2
+12V
GND
+12V
GND
bit
Totem-Pole Putput and Zener Clamp
+12V
+12V
Register
+
-
Output and Register Attenuator
PNP Transistor
C
Publication Release Date: April 14, 2006
Pull-up resister < 1K
or totem-pole output
Pull-up resister
4.7K Ohms
Value
14K~39K
3.9V Zener
FAN
> 1K
×
100
Fan Input
Fan Input
10K
%
W83791D/G
Pin 18/19/20
Pin 18/19/20
W83791D
W83791D
Revision 1.1