W83792AD/AG/D/G
+12V
+5V
+12V
Pull-up resister
4.7K Ohms
Pull-up resister
4.7K Ohms
+12V
FAN Out
GND
+12V
FAN Out
GND
14K~39K
Fan Input
Fan Input
Pin 18/19/20
Pin 18/19/20
10K
W83792D
W83792D
FAN
Connector
FAN
Connector
Figure 5-2. Fan with Tach Pull-Up to +12V, or Totem-Pole
Output and Register Attenuator
Figure 5-1. Fan with Tach Pull-Up to +5V
+12V
+12V
Pull-up resister < 1K
or totem-pole output
Pull-up resister
> 1K
+12V
+12V
> 1K
Fan Input
FAN Out
Fan Input
FAN Out
Pin 18/19/20
Pin 18/19/20
GND
GND
3.9V Zener
3.9V Zener
W83792D
W83792D
FAN
Connector
FAN
Connector
Figure 5-4. Fan with Tach Pull-Up to +12V, or
Totem-Pole Putput and Zener Clamp
Figure 5-3. Fan with Tach Pull-Up to +12V
and Zener Clamp
7.7.2 Fan speed control
The W83792D/G provides six sets both of PWM and DC mode for fan speed control. The duty cycle of
PWM can be programmed by a 4-bit registers defined in the Bank0 CR[81], CR[83], CR[94],
CR[A3],CR[A4] and CR[A5] . The default duty cycle is set to 100%, that is, the default 4-bit register is
set to 0x8Fh. The expression of duty cycle can be represented as follows.
Publication Release Date: April 26, 2006
- 21 -
Revision 0.9
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