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LB1863M/LB1869M

4. Output protection function (C pin)

This pin connects the capacitor that forms the automatic recovery circuit. If rotation stops due to, for example, a

motor overload, the pin voltage rises and the output stops. The system automatically recovers from stopped to drive

mode when the load is set to an appropriate level. The lock detection time can be set by changing the value of the

capacitor.

For a 1-μF capacitor:Lock detection time

About 2 seconds

Lock protection time (output on) About 1 second

(output off) About 6 seconds

➀While the blades are turning, the capacitor is charged with a current of about 3 μA (typical), and C is discharged by

pulses that correspond to the motor speed.

➁When the blades lock, the capacitor is no longer discharged, and the voltage across the capacitor increases. The

output is turned off when that voltage reaches 0.8

➂When the output is turned off, the capacitor is discharged at a current of about 0.44 μA (typical). When the

ton:toff ratio of about 1:6 to protect the motor.

output on.

5. Rotation detection signal (RD pin)

This is an open collector output, and outputs a low level in drive mode and a high level when the motor is stopped.

6. Radio-frequency noise reduction function (B1 and B2 pins)

These are base pins for Darlington pair outputs. Add capacitors of about 0.01 to 0.1 μF if radio-frequency noise is a

problem.

7. Thermal shutdown function

Turns off the output in response to coil shorting or IC overheating.

Automatic recovery circuit pin C voltage