W83782D Datasheet, PDF (25/73 Pages) Winbond – MONITORING IC

Preliminary W83782D
+12V
+12V
FAN Out
GND
FAN
Connector
+5V
Pull-up resister
4.7K Ohms
Fan Input
Pin 18/19/20
W83782D
Figure 13-1. Fan with Tach Pull-Up to +5V
+12V
+12V
FAN Out
GND
FAN
Connector
Pull-up resister
> 1K
Fan Input
Pin 18/19/20
3.9V Zener
W83782D
Figure 13-3. Fan with Tach Pull-Up to +12V
and Zener Clamp
+12V
+12V
FAN Out
GND
FAN
Connector
Pull-up resister
4.7K Ohms
14K~39K
Fan Input
Pin 18/19/20
10K
W83782D
Figure 13-2. Fan with Tach Pull-Up to +12V, or Totem-Pole
Output and Register Attenuator
+12V
+12V
FAN Out
GND
FAN
Connector
Pull-up resister < 1K
or totem-pole output
> 1K
Fan Input
Pin 18/19/20
3.9V Zener
W83782D
Figure 13-4. Fan with Tach Pull-Up to +12V, or
Totem-Pole Putput and Zener Clamp
6.4.2 Fan speed control
The W83782D provides four sets for fan PWM speed control. The duty cycle of PWM can be
programmed by a 8-bit registers which are defined in the Bank0 CR5A, CR5B, CR5E, and CR5F. 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.
Duty − cycle(% ) = ^{Programmed 8 - bit Register Value} × 100%
255
The PWM clock frequency also can be program and defined in the Bank0.CR5C and Bank4.CR5C.
The application circuit is shown as follows.
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Publication Release Date: April 1999
Revision A1