W83783S Information Storage Devices, Inc, W83783S Datasheet - Page 20

• Manufacturer Part Number: W83783S
• Description: H/w Monitor: 3 Temp.(thermal Diode), 6 Vol., 2 PWM Fan Control
• Manufacturer: Information Storage Devices, Inc

6.4.2 Fan speed control
The W83783S 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 and CR5B. 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.
The PWM clock frequency also can be program and defined in the Bank0.CR5C . The application
circuit is shown as follows.
Connector
Connector
Figure 13-1. Fan with Tach Pull-Up to +5V
Figure 13-3. Fan with Tach Pull-Up to +12V
FAN
FAN
FAN Out
FAN Out
and Zener Clamp
+12V
+12V
GND
+12V
GND
+12V
diode
Duty
diode
3.9V Zener
cycle
Fan Input
Fan Input
+5V
Pull-up resister
Pull-up resister
4.7K Ohms
(% )
> 1K
Pin 18/19/20
Pin 18/19/20
W83783S
W83783S
Programmed 8 - bit Register Value
- 15 -
Connector
Connector
FAN
Figure 13-2. Fan with Tach Pull-Up to +12V, or Totem-Pole
Figure 13-4. Fan with Tach Pull-Up to +12V, or
FAN
255
FAN Out
FAN Out
+12V
GND
+12V
GND
Totem-Pole Putput and Zener Clamp
+12V
+12V
Output and Register Attenuator
Publication Release Date: April 1999
diode
diode
3.9V Zener
> 1K
Pull-up resister
4.7K Ohms
14K~39K
100%
Pull-up resister < 1K
or totem-pole output
Fan Input
Fan Input
10K
W83783S
Preliminary
Revision 0.55
Pin 18/19/20
Pin 18/19/20
W83783S
W83783S