LB11850VA

No.A0609-8/14

Description of Speed Control Block

1) Speed control diagram

2) Timing at startup (soft start)

Determined by LIM pin voltage

CR time constant large

CR time constant small

The speed slope is determined by the constant of the RC pin.

(RPM)

Rotation speed

Minimum speed

Small

← CTL signal (PWMDUTY) → Large

Large

← EO pin voltage (V) → Small

0%

100%

0V

Variable speed

Full speed

5VREG

ON-Duty small

ON Duty large

Minimum speed

setting rotation

LIM voltage

CTL pin

EO pin

EO voltage

Soft start

The slope changes according to the capacitance of SOFT pin.

(Large

→ Large slope)

CTL pin

Stop

VCC pin

SOFT pin

Full speed

Stop

Full speed