LB11850VA Datasheet, PDF (12/14 Pages) Sanyo Semicon Device – Monolithic Digital IC For Fan Motor Single-Phase Full-Wave Pre-Driver with Speed Control Function

LB11850VA
(2) Movement along the Y-axis (resistance divided between CVO and VCC)
(RPM)
Motor
at maximum speed
Move in the direction
of the Y-axis
0%
CTL Duty(%)
100%
(Example) In the case where the characteristics change from ones with the origin point (0%, 0 rpm) to ones where the
speed at a duty ratio of 25% becomes 0 rpm:
First, obtain the CVO pin voltage required for the CVI voltage to be 5V at 25%.
CVO = 5-(3×duty ratio) = 5-(3×0.25) = 5-0.75 = 4.25V
With CVO = 4.25V, find the resistances at which CVI = 5V.
The ratio of CVO-CVI: CVI-GND is 0.75V: 7V = 1: 9.3
Based on the above, the resistance is 20kΩ between CVO and CVI and 180kΩ between CVI and VCC.
(Due to the current capacity of the CVO pin, the total resistance must be set to 100kΩ or more.)
Furthermore, the slope changes. (In the case of the example given, since the resistance ratio is 1: 9.3, the slope is now
9.3/10.3 = 0.9 times what it was originally.)
If necessary, change the resistance of the RC pin, and adjust the slope.
VCC
R5
R4
LIM
SOFT
CVI
CVO
VREF
C
CTL
CTL
No.A0609-12/14