w83l784r Winbond Electronics Corp America, w83l784r Datasheet - Page 22

• Manufacturer Part Number: w83l784r
• Description: Winbond H/w Monitoring Ic
• Manufacturer: Winbond Electronics Corp America

6.5.2 Fan speed control
The W83L784R provides four sets for fan PWM speed control. The duty cycle of PWM can be
programmed by a 8-bit register which are defined in the Bank0 CR81h and CR83h. The default duty
cycle is set to 100%, that is, the default 8-bit registers is set to FFh. The expression of duty can be
represented as follows.
Connector
Connector
Figure 15-1. Fan with Tach Pull-Up to +5V
Figure 15-3. Fan with Tach Pull-Up to +5V
Confidential, For Beta-site Only
FAN
FAN
FAN Out
and Zener Clamp
FAN Out
+5V
+5V
GND
+5V
GND
+5V
diode
Duty
diode
3.9V Zener
Fan Input
cycle
Fan Input
+5V
Pull-up resister
Pull-up resister
4.7K Ohms
(%)
> 1K
Pin 1 / 2
Pin 1 / 2
W83L784
R
W83L784
R
Programmed 8 - bit Register Value
-21 -
Connector
Connector
FAN
FAN
Figure 15-4. Fan with Tach Pull-Up to +5V, or
255
FAN Out
Figure 15-2. Fan with Tach Pull-Up to +5V, or Totem-Pole
FAN Out
+5V
GND
Totem-Pole Putput and Zener Clamp
+5V
GND
+5V
+5V
diode
Output and Register Attenuator
diode
Publication Release Date: Sep.
3.9V Zener
Pull-up resister < 1K
or totem-pole output
> 1K
Pull-up resister
4.7K Ohms
100%
2K
W83L784R
Fan Input
Fan Input
10K
Preliminary
Revision 0.54
Pin 1 / 2
Pin 1 / 2
W83L784R
W83L784R
1999