Model : IW-RS424-07 Hybrid EXP-
BP (COBRA) User’s Manual
PAGE 15 OF 22
Smart Fan Control
InWin
’s Backplane is implemented Smart Fan Control feature by automatically detecting the
existences of the Fan Modules and intelligently control the Fan RPM per the system
temperature being detected by two thermal sensors (RTB1/RTB2) on the backplane.
Thanks to Smart Fan Control feature the Fan connectors (FAN1/FAN2/FAN3/FAN4) on
backplane support wide variety of PWM driven Fan modules being used in the enclosure.
How it works?
1. Fan module auto-calibration triggered in every system boot. The thermal profile would
then be recorded and used until next reboot.
2. Backplane starts fan calibration and calculates the corresponding PWM duty cycle for
each level. There are totally 8 speed levels to be sensed and used until next system boot.
3. The 8 levels of fan speed are mapped to the temperature readings detected by thermistor
spreading from 25 to 45
°C
in 3.75 degree C step.
4. In normal operation, when the system temperature changes to next level, the fan module
would change speed accordingly. And, the Fan failure alarm would be triggered when the
RPM of the Fan module is dropped lower than 75% of its expected speed.
5. The fan module calibration and thermal profile are as below.
6. When an external PWM source joins, the output PWM duty is determined by comparing
the internal calculated PWM and external PWM and then select whichever is higher as
the output PWM to the fan modules.
