笔记本风扇控制方案Word下载.doc

1、红（绿）+12V/+5V 供电+12V黄风扇转速侦测蓝无PWM3pin风扇的控制，通过将EC出去的PWM转化出稳定的电压，然后再送给风扇的正极，通过电压的高低来控制风扇的转速。4pin风扇的控制，首先需要恒定的+12v电压，风扇的转速大小是直接由PWM控制。PWM的频率根据实际风扇及噪音的大小来设定。二、风扇转速侦测表RPMRound/1 minRound/secu sec/ RoundCounter value for 1PPR FAN6000100（6000/60 sec）10000333（10000/30）500083.33（5000/60）12000400（12000/30）40006

2、6.667（4000/60）15000500（15000/30）300050（3000/60）20000666（20000/30）200033.333（2000/60）300001000（30000/30）100016.667（1000/60）600002000（40000/30）5008.3（500/60）1200004000（120000/30）RPM （round / min） = 60,000,000 / （FANMON*30）To enable the monitor function of fan feedback speed, the FANCFG bit_0 should be

3、 set. If fan speed is too slow to calculate, the fan timeout error flag （FANSTS bit_1） will be set. The interrupt should be set when monitoring update interrupt and timeout interrupt. The update flag is in FANSTS bit 0.The Fan PWM is a 12-bit counter clocked by system clock with a resulting 4.0960.2

4、56ms cycle time. If FANCFG bit_1 is set, the PWM is controlled automatically by comparing the difference between FANMON （FAN monitor speed） and FANSET （set FAN target speed）. If FANMON is larger than FANSET, it indicates the current fan speed is too slow, the PWM should increase its duty cycle to in

5、crease the fan speed, and vice versa. The PWM will remain still if （FANMON FANSET） is less than four. If FANCFG bit_1 is clear, the PWM is controlled manually by firmware. Please note that the FANPWM value should be set by low-byte then high-byte sequence要打开风扇转速侦测功能，FANCFG_BIT 0 要置为1。三、风扇损坏处理方案根据本机种设定最低转速时的FANMON为判断点，如果反馈回来的FANMON的值小于此判断点，同时CPU或GPU温度达到风扇的最低停转点，1， 先至少降频5s。2， 如果条件仍然成立，就shutdown。