1 When a fan is rotating, the capacitor is charged at 4 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 0.8 × V

3 When the output is turned OFF, discharge occurs through the C at 0.5 µA (typ). If the lock is not released when the C voltage

3 repeated at a cycle of approximately t

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

(6) Rotation detect signal (RD pin)

.

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

(7) Radio noise reducing (Pins B1, B2)

.

Base pin of Darlington connection output transistor

.

If radio noises need to be processed properly, the following actions should be taken:

1 Connect a capacitor of 0.01 µ to 0.1 µF between B1 and B2.

2 Connect a capacitor of 0.001 µ to 0.01 µF between OUT and B.

If output causes oscillation, add a resistor of 200

Ω to1kΩ in series with a capacitor.

(8) Thermal shutdown function

.

Shutdown the driver output in case of coil short-circuiting and abnormal IC heating.

Thermistor-controlled Application Circuit Example

Output Timing Chart

Noise elimination

capacitor

Figure 2

(

): MFP14S

Unit (resistance:

Ω, capacitance: F)

Use of a thermistor enables motor speed to

be sensitive to the operating ambient

temperature.

The Rt pin voltage at Ta = 20 °C has

4 with the application constant of Figure 2.

However, the Rt pin voltage at Ta = 40 °C

is reduced into less than the Vct (= 1.3 V)

means the 100% duty.

t = –C2 c R2 c 1n

............. 4

Hall input

Discharge pulse

Ct voltage

Output ‘off’ signal

OUT1 current

OUT2 current

All-phase ON waveform

Control output waveform

Figure 3

LB1860,1860M,1861,1861M

No.3519-5/6