When "Tiny Cooling Fan" operate at zero speed or full speed, passive components are either completely closed in zero speed or fully on in full speed. In this case, all the power is transferred to the BLDC fan. And it also means that no power is wasted in passive components. But when the BLDC "Tiny Cooling Fan" when not in zero or full speed, passive components will waste some power, so the efficiency of this method is questionable. Since this method is no speed monitoring, therefore, can not understand the state of the fan. In order to ensure "Tiny Cooling Fan" to start, it needs to within 60% of the maximum voltage selection start voltage, so that the speed can be controlled in the range of 40% of the remaining portion (ie 60-100% of maximum speed).