LB11850VA Datasheet, PDF (8/14 Pages) Sanyo Semicon Device – Monolithic Digital IC For Fan Motor Single-Phase Full-Wave Pre-Driver with Speed Control Function

LB11850VA
Description of Speed Control Block
1) Speed control diagram
(RPM)
The speed slope is determined by the constant of the RC pin.
CR time constant small
CR time constant large
Rotation speed
Minimum speed
Determined by LIM pin voltage
0%
Small ← CTL signal (PWMDUTY) → Large
Large ← EO pin voltage (V) → Small
Minimum speed
setting rotation
Variable speed
ON-Duty small
CTL pin
100%
Full speed
ON Duty large
5VREG
EO pin
0V
LIM voltage
EO voltage
2) Timing at startup (soft start)
VCC pin
CTL pin
SOFT pin
Stop
Stop
Full speed
Soft start
The slope changes according to the capacitance of SOFT pin.
(Large → Large slope)
Full speed
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