As well as the standard single function signals such as fan-fail, tachometer speed information and speed control from temperature sensors and pulse width modulation (PWM) circuitry, multi function fans are also available with any combination of these functions thus providing maximum control and design flexibility for the thermal engineer.
PWM combined with either tachometer or fan-fail signal offer the power saving advantages of PWM while being able to monitor the fan performance in terms of fan speed or fan-fail condition.
The use of a variable speed sensor combined with tachometer or fan-fail signal offer the advantage of controlling the performance of the fan relative to temperature conditions while also monitoring fan speed and detecting fan failure. Combining tachometer sensor plus fan-fail detector provides the ability to monitor both the speed of the motor and the fan-fail condition.
These options are available in the larger frame sizes of fans of 120 and 92mm square and new models within the smaller frame sizes are being introduced to meet customer demand.