W83L785R Datasheet, PDF (16/38 Pages) Winbond – WINBOND H/W MONITORING IC FOR NOTEBOOK

W83L785R/W83L785G
+5V
+5V
FAN Out
GND
Pull-up resister
4.7K Ohms
1K~2.7K
Fan Input
Pin 1
Pin 2
10K
W83L785R
Figure 7-3. Fan with Tach Pull-Up to +5V, or Totern-Pole
Output and Register Attenuator
+5V
+5V
FAN Out
GND
FAN
Connector
Pull-up resister < 1K
or totem-pole output
> 1K
Fan Input
Pin 1
Pin 2
3.3V Zener
W83L785R
Figure 7-4. Fan with Tach Pull-Up to +5V, or
Totem-Pole Putput and Zener Clamp
6.6.2 Fan speed control
The W83L785R/G provides two sets for fan PWM speed control. The duty cycle of PWM can be
programmed by an 8-bit register which are defined in the 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.
Duty − cycle (%) = ^Programmed
8 - bit Register Value _{× 100 %}
255
+12V
+5V
PWM Clock Input
R1
R2
D
G
NMOS
S
PNP Transistor
+
C
-
FAN
PWM Clock Input
R1
R2
D
G
NMOS
S
PNP Transistor
+
C
-
FAN
6.7 SMI#
Figure 8
6.7.1 Temperature
Pin SMI# for temperature has 3 modes.
6.7.1.1. Comparator Interrupt Mode
Temperature exceeding T_O causes an interrupt and this interrupt will be reset when reading all of the
Interrupt Status Registers. Once an interrupt event has occurred by exceeding T_O, then reset, if the
temperature remains above the T_HYST, the interrupt will occur again when the next conversion has
completed. If an interrupt event has occurred by exceeding T_O and not reset, the interrupts will not
occur again. The interrupts will continue to occur in this manner until the temperature goes below
T_HYST. (Figure 9-1)
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