Fan Motor Speed Controller 12V 8-Pin DSO
The Fan Speed Controller is a fully integrated control with few external components to set up a flexible and low cost application. The device uses the waveform of the current in a standard two-wire fan to detect the speed of revolution and to control it. The current flowing through the fan is sensed by the shunt resistor connected to RSin. For fans with a supply current between 50mA and 400mA, a good value for this resistor is between 0.5 and 1Ω as the maximum input voltage of RSin for linear operation is 330mV The Pulse Detector circuit creates one internal trigger pulse at every commutation of the fan motor. The internal trigger pulse will be processed if the current waveform through the motor shows appropriate variations at the commutation. Monitoring and warning signal can be used to check the working condition. Every two internal trigger pulses one is fed to the FanM output to monitor the speed of rotation. The device controls the speed of revolution. The temperature is measured with the NTC thermistor and according to the voltage on the NTC the speed of the fan is set.