W83637HF Datasheet, PDF (36/149 Pages) Winbond – LPC I/O

W83637HF
6.4.2 Fan speed control
The W83637HF provides maximum 3 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 Index 01h, Index 03h and Index 11h.
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 Index 00h, Index 02h and
Index 10h. The application circuit is shown as follows.
+12V
R1
R2
PWM Clock Input
D
G
NMOS
S
PNP Transistor
+
C
FAN
-
Figure 6.5
- 31 -
Publication Release Date: June 25, 2003
Revision 1.3