Suppressing Acoustic Noise in PWM Fan Speed Control Systems
Fan speed control extends fan service life and decreases acoustic airflow noise and average fan current. The most efficient way to implement fan speed control is to use low frequency pulse width modulation (PWM). However, PWM fan speed control can sometimes introduce unwanted acoustic noise at a frequency equal to that of the PWM itself. This is especially noticeable when PWM control is used with higher operating current (>300 mA) fans and at low operating speeds. This application note discusses the source of this acoustic noise and a method to suppress it.
Accoustic, Noise, Suppressing, PWM, Fan