f75377 Feature Integration Technology Inc., f75377 Datasheet - Page 18

• Manufacturer Part Number: f75377
• Description: Monitor With Automatic Speed Control
• Manufacturer: Feature Integration Technology Inc.

Once temp. is under 40°C, the lowest fan speed keeps 50% PWM duty. Once temp. is over 40°C,60°C,
the fan speed will vary from 70% to 100% PWM duty and increase with temp. level. Once temp. keeps in
55°C, fan speed keeps in 70% PWM duty. If set the hysteresis as 3°C (default 4°C), once temp reduces
under 57°C, fan speed reduces to 70% PWM duty and stays there.
Linear auto mode
Otherwise, F75377 supports linear auto mode. Below has a example to describe this mode. More detail,
please refer the register description.
Set temperature as 70°C, 40°C and Duty as 100%, 70%, 40%
Once temp. is under 40°C, the lowest fan speed keeps 40% PWM duty. Once temp. is over 40°C and
under 70°C, the fan speed will vary from 40% to 70% PWM duty and linearly increase with temp.
variation. The temp.-fan speed monitoring and flash interval is 1sec. Once temp. goes over 70°C, fan
speed will directly increase to 100% PWM duty (full speed). If set the hysteresis as 5°C(default is 4°C),
once temp reduces under 65°C (not 70°C), fan speed reduces from 100% PWM duty and decrease
linearly with temp..
hysteresis 57 Degree C
hysteresis 65 Degree C
Temp.
Fan Speed
Temp.
Fan Speed
60 Degree C
40 Degree C
70 Degree C
40 Degree C
a
a
b
18
b
c
c
PWM duty
d
d
100%
70%
50%
PWM duty
100%
70%
40%
F75377
March.
V0.12P
, 2008