W83L784R_05 Datasheet, PDF (20/52 Pages) Winbond – Monitoring IC

W83L784R/ W83L784G
+5V
diode
+5V
FAN Out
GND
FAN
Connector
+5V
Pull-up resister
4.7K Ohms
Fan Input
Pin 1 / 2
W83L784
R
Figure 15-1. Fan with Tach Pull-Up to +5V
+5V
+5V
diode
+5V
FAN Out
GND
FAN
Connector
Pull-up resister
4.7K Ohms
2K
Fan Input
Pin 1 / 2
10K
W83L784R
Figure 15-2. Fan with Tach Pull-Up to +5V, or Totem-Pole
Output and Register Attenuator
+5V
+5V
FAN Out
GND
FAN
Connector
diode
Pull-up resister
> 1K
Fan Input ^{Pin 1 / 2}
3.9V Zener
W83L784
R
+5V
FAN Out
GND
FAN
Connector
diode
Pull-up resister < 1K
or totem-pole output
> 1K
Fan Input
Pin 1 / 2
3.9V Zener
W83L784R
Figure 15-3. Fan with Tach Pull-Up to +5V
and Zener Clamp
Figure 15-4. Fan with Tach Pull-Up to +5V, or
Totem-Pole Putput and Zener Clamp
6.5.2 Fan speed control
The W83L784R/G provides four sets for fan PWM speed control. The duty cycle of PWM can be
programmed by an 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.
Programmed 8 - bit Register Value
Duty − cycle(%) =
× 100%
255
+5V
PWM Clock Input
R1
R2
D
G
NMOS
S
PNP Transistor
+
C
-
FAN
Figure 16
- 15 -
Publication Release Date: Jan. 2005
Revision 1.1