F2867

LINEAR INTEGRATED CIRCUIT

UNISONIC TECHNOLOGIES CO., LTD

6 of 6

www.unisonic.com.tw

QW-R109-038.C



T Y PI CAL APPLI CAT I ON CI RCU I T (Cont .)

Notes: *5. CPWM pin

Pin to connect the capacitor for generation of the PWM basic frequency

The use of CP=220pF causes oscillation at f=30kHz, which is the basic frequency of PWM.

As this is used also for the current limiting canceling signal, be sure to connect the capacitor even when

the speed control is not made.

*6. RMI pin

Minimum speed setting pin.

Perform pull-up with 5VREG when this pin is not to be used.

If the IC power supply is likely to be turned OFF first when the pin is used with external power supply, be

pin.)

Speed control pin.

Connect this pin to GND when it is not used (at full speed).

For the control method, refer to the timing chart.

For control with pulse input, insert the current limiting resistor and use the pin with the frequency of

20k~100kHz (20kHz~50kHz recommended).

*8. SENSE pin

Current limiting detection pin.

When the pin voltage exceeds 0.2V, the current is limited and the operation enters the lower regeneration

mode.

Connect this pin to GND when it is not to be used.

*9. FG pin

Rotation speed detection pin.

This is an open collector output, which can detect the rotation speed from the FG output according to the

phase changeover.

Keep this pin open when it is not to be used.

*10. CT pin

Pin to connect the lock detection capacitor.

The constant-current charge and discharge circuits incorporated cause locking when the pin voltage

becomes 3.0V and unlocking when it is 1.1V. Connect the pin to GND when it is not to be used (locking

not necessary).

*11. S-S pin

Pin to connect the soft-start setting capacitor.

Connect the capacitor between 5VREG and S-S pin.

This pin enables setting of the soft start time according to the capacity of the capacitor.

See the timing char.

Connect the pin to GND when it is not to be used.

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