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13.3.3
Luminance Adjustment Function (V
Figure 13.13 shows a detailed block diagram of the LCD drive power supply unit.
The voltage output to the V
drive power supply, the V
R, between the V
and V
0
to provide luminance adjustment for the LCD panel.
13.3.4
Low-Power-Consumption LCD Drive System
The use of the built-in split-resistance is normally the easiest method for implementing the LCD
power supply circuit, but since the built-in resistance is fixed, a certain direct current flows
constantly from the built-in resistance's V
current dissipation of the LCD panel, if an LCD panel with a small current dissipation is used, a
wasteful amount of power will be consumed. The H8/3864 Series is equipped with a function to
minimize this waste of power. Use of this function makes it possible to achieve the optimum
power supply circuit for the LCD panel's current dissipation.
pin is V
When either of these voltages is used directly as the LCD
0
CC.
and V
pins should be shorted. Also, connecting a variable resistance,
0
1
pins makes it possible to adjust the voltage applied to the V
1
V
CC
V
SS
Figure 13.13 LCD Drive Power Supply Unit
to V
CC
Pin)
0
V
0
V
1
V
2
V
3
. As this current does not depend on the
SS
pin, and so
1
R
343
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