Microchip Technology

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  • Microcontroller Based Predictive Fan Failure Detector

  • Created: Feb 02, 2017

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System and equipment had increased in power and speed in terms of computing power in the years. With the increase in power and speed, the components generate more heat in which passive cooling will no longer work. More heat without any way of cooling will lead to overheating that can damage the components lifespan and can cause malfunction. Using cooling fans can help move the heat away and draws cooler air to the component. Even with cooling fans, in system that requires constant cooling, a failure of operation in the fan can cause thermal damage to the system. The TC670 is an integrated fan speed sensor that predicts and detects fan failure; this prevents thermal damage to the system with cooling fans due to failure of operation of the fans. The failure detection works with all linear-controlled 2-wire fans. It can operate at a temperature range of -40°C to +85°C.

The circuit design is a fan failure detector based on a microcontroller that can predict if the fan is slowing down. The circuit is supplied by a +5V USB connection. This supplies the microcontroller, TC670, and the fan. The fan is a 5V axial fan that is connected to the SENSE pin of the TC670. Voltage pulses, which are generated by the fan current flowing through a sense resistor, are detected at the SENSE pin and used to calculate the fan speed. The TC670 senses the fan pulses and internally converts those pulses from a frequency into an analog voltage. This voltage is then compared with the DC voltage at the THRESHOLD pin. If the converted frequency-to-voltage value from the fans pulses falls below the threshold voltage, the /ALERT output is pulled LOW. The voltage at the THRESHOLD input sets the equivalent minimum allowable fan speed for the application. The THRESHOLD voltage is set at 2.4V that can cover most common fan 3V to 5V supply. The CLEAR pin allows the user to reset the /ALERT pin to a high status. A switch is provided to trigger the clear function of the TC670 if a fail occurs.

The use of fans to cool equipment has improved the lifespan and functionality of the components to run smoothly and faster. It is commonly used in notebooks, computers, data storages and industrial equipment. With the failure detector, the components are much more protected from unnoticed fan failures than can cause damage to equipment due to overheating.