lb11850va Sanyo Semiconductor Corporation, lb11850va Datasheet - Page 11

• Manufacturer Part Number: lb11850va
• Description: For Fan Motor Single-phase Full-wave Pre-driver With Speed Control Function
• Manufacturer: Sanyo Semiconductor Corporation

<CVO, CVI pins>
These pins determine the position of the slope origin. (When the origin point is at (0%, 0 rpm), CVO and CVI are
shorted.)
(1) Movement along the X-axis (resistance divided between CVO and GND)
(Example) In the case where the characteristics change from ones with the origin point (0%, 0 rpm) to ones where the
Next, obtain the resistances at which the voltage becomes 4.1V by dividing the resistance between CVO and GND
when CVO is 5V. The ratio of CVO-CVI: CVI-GND is 0.9V: 4.1V = 1: 4.5.
Based on the above, the resistance is 20kΩ between CVO and CVI and 91kΩ between CVI and GND.
Furthermore, the slope changes. (In the case of the example given, since the resistance ratio is 1: 4.5, the slope is now
4.5/5.5 = 0.8 times what it was originally.)
If necessary, change the resistance of the RC pin, and adjust the slope.
Motor
at maximum speed
speed at a duty ratio of 30% becomes the speed at 0%:
First, obtain the input voltage of the CVI pin required at 0%.
CVI = 5-(3×duty ratio) = 5-(3×0.3) = 5-0.9 = 4.1V
(RPM)
0%
R4
R5
Move in the direction
of the X-axis
C
SOFT
CTL
LIM
CVI
CVO
LB11850VA
CTL
VREF
CTL Duty(%)
100%
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