1 When a fan is rotating, the capacitor is charge at 2.8 µA (typ) and discharged through the C with pulses according to the

rotational speed.

2 When a fan is locked, no discharge occurs through the C and the C voltage rises, turning OFF the output at V

3 When the output is turned OFF, discharge occurs through the C at 0.38 µA (typ). If the lock is not released when the C

4 If the lock is released when the C voltage drops to V

(5) Rotation detect signal (RD pin)

Open collector output (Drive mode: ‘‘L’’, Stop mode: ‘‘H’’)

(6) Radio noise reducing (B1 and B2 pins)

These are the base pins for Darlington connected output transistors. If radio noise is a problem, add a capacitor of

approximately 0.01 to 0.1 µF between B1 and B2, or 0.001 µF to 0.01 µF between OUT and B.

Block Diagram and Sample Application Circuit − 1

Control block

Low

current

circuit

0.47 to 10µF

*1 Use (10,000 to 100,000 pF) if radio noise is a problem.

*2 Use a Zener diode or capacitor for output stage protection.

LB1662D, 1662M

No.3416-5/6