UTCUA9406

LINEAR INTEGRATED CIRCUIT

3

QW-R109-014,A

LOCK DETECTION

The automatic restart circuit detects a motor lock condition and automatically turns off the output current. When

the lock condition is cleared, the IC automatically restarts and allow the motor to run.

In the UTC UA9406, automatic restart is performed in the following manner. A motor lock condition is detected

when the Hall signal stops switching. The output is ON when pin 6 is being charged, and OFF when pin 6 is being

discharged. Pin 3 is ON during normal operation, and OFF when the motor is locked. Pin 3 is an open collector

output.

Hall input

Motor output

6 pin

3pin L

Motor

locked

Motor lock detected

High

Pin6

comparator

voltage

Motor lock

cleared

Reverts to normal operation

Fig.1

OFF

Pin6

clamp

voltage

ON

(sec)

(sec)

C is the capacitance of the pin-6 external capacitor

OPERATION NOTES

(1) The lock detection output pin (pin 3) may maintain

HIGH level for a few hundred milliseconds when the power is turned on.

Power

3 pin

A few hundred millseconds

Fig.2