CFM-70 Datasheet, PDF (4/5 Pages) CUI INC – DC AXIAL FAN

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CUI Inc │ SERIES: CFM-70 │ DESCRIPTION: DC AXIAL FAN
date 08/15/2016 │ page 4 of 5
APPLICATION NOTES
Auto Restart Protection/Current Limit Protection
When the fan motor is locked, the device will cut off the drive current within two to six seconds and restart automatically
after a few seconds. If the lock situation is continued, the device will work on a repeated cycle of cut-off and restart until
the lock is released. (See Figure 1 below).
Figure 1 Current Limit Protection
Lock Sensor/Rotation Detector
Lock Sensor is used to detect if the fan motor is operating or stopped. Alarm High: the output will be logical low when fan
is operating and be logical high when fan motor is locked. (See Figures 2~3 below).
Figure 2 Alarm High
Output Waveform
Figure 3 RD Signal Output Circuit:
Open Collector
Ic=5mA max
Pulse Sensor/Tachometer Signal/FG
Pulse Sensor is for detecting the rotational speed of the fan motor. At locked rotor condition, the signal stops cycling and
the output is fixed at VoH or VoL (See Figures 4~5 below).
Figure 4 Output Waveform
Figure 5 FG Signal Output Circuit:
Open Collector
Ic=10mA max
PMW Control Signal
A speed control lead can be provided that will accept a PWM signal from the customer circuit to vary the speed of the fan.
The change in speed is linear by changing the Duty-Cycle of the PWM. Open collector type and pull-up voltage is changed
by maximum operating voltage and sink current by consuming current. (See Figure 6 below).
Figure 6 Duty Cycle
Vs=4~5 V
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