CUI DEVICES | SERIES: CFM-40CF | DESCRIPTION: DC AXIAL FAN

date 08/12/2022 | page 6 of 7

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APPLICATION NOTES

Auto Restart Protection

When the fan motor is locked by an external force, the device will temporarily turn off electrical power to the motor and restart

automatically when the locked rotor condition is released.

Tachometer Signal (Yellow Wire)

The tachometer signal is for detecting the rotational speed of the fan motor. The output will be a square wave when fan is operating and

VFG or VCE depending on the locked rotor position when fan motor is locked (See Figures 1~2 below).

Figure 1: Tachometer

Output Circuit

Figure 2: Tachometer

Output Waveform

Polarity Protection

Able to withstand 10 minutes of reverse polarity connection between the positive and negative wires without causing damage.

Output Type: Open Collector

Vs: (VFG)

5 V fan: 3.3~5 V

All others: 3.3~15 V

Ic≤5 mA

R≥Vs/Ic

VCE(sat)≤0.5 V

4 Pole Motor

N=RPM

T=60/N (sec)

FG=1/T*2 (Hz)

N=FG*30

PWM Duty Cycle (%) = T1/T x 100%

PWM Frequency Range: 20~30 kHz

PWM VIH = 2.8~5.5 V

PWM VIL = 0~0.6 V

Figure 3: PWM Input Signal

PWM Signal (Blue Wire)

This wire is for speed control of the fan motor using a PWM input signal from the customer circuit (See Figure 3 below).

Additional Resources: Product Page | 3D Model