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Fan lock sensor: operation details

DC Fan sensor output

In the ASFN series, the models designated "with lock sensor" have an additional output. If the fan propeller is blocked, a rectangular alarm signal is triggered at the sensor output. This signal can be used with an external circuit in order to monitor the fan - for example, to keep it from overheating.

1. Sensor output switch action

fan guard


  • 1. Output may be high for approximately 0.5s when power is turned on.
  • 2. In case of fan blockage, the sensor signal is at a constant high.

2. External circuit

fan guard


  • 1. Set the resistance (R) at a value which ensures that the sensor circuit current (lc) does not exceed 5mA.
  • If the sensor output is operating at the TTL level,the sensor circuit current (lc) should be approximately 2mA.

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