F71862
There are some modes to control fan speed and they are 1.Manual mode, 2.Stage
auto mode, 3. Linear auto mode. More detail, please refer the description of registers.
Manual mode
For manual mode, it generally acts as software fan speed control.
Stage auto mode
At this mode, the F71862 provides automatic fan speed control related to temperature
variation of CPU/GPU or the system. The F71862 can provide two temperature boundaries
and three intervals, and each interval has its related fan speed PWM duty. All these values
should be set by BIOS first. Take figure 7-10 as example. When temperature boundaries are
set as 45 and 75°C and there are three intervals. The related desired fan speed for each
interval are 40%, 80% and 100% (fixed). When the temperature is within 45~75’C, the fan
speed will follow 80% PWM duty and that define in registers. It can be said that the fan will
be turned on with a specific speed set by BIOS and automatically controlled with the
temperature variation. The F71862 will take charge of all the fan speed control and need no
software support.
Temperature
PWM Duty
100%
75 Degree C
80%
40%
45 Degree C
Temperature
Fan Speed
Figure 7-10
Below is a sample for Stage auto mode:
Set temperature as 60°C, 40°C and Duty as 100%, 70%, 50%
PWM duty
100%
60 Degree C
hysteresis 57 Degree C
70%
50%
40 Degree C
Temp.
a
b
c
d
Fan Speed
47
July, 2008
V.28P
FINTEK [ FEATURE INTEGRATION TECHNOLOGY INC. ]
