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13.3.14 Contrast Control Circuit
Contrast control can be performed by software (electronic control function) by controlling the
LCD drive voltage (the potential difference between V
register (LRA). Variable resistance value V
where R is the value of the basic dividing bleeder resistance between V
control settings by bits CCR3 to CCR0 in the contrast control register (LRA) are shown in table
13.7.
To ensure stable operation of the voltage follower op-amp circuits that output levels V1 to V5, the
contrast control register (LRA) should be set so that the potential difference between V
and between V5 and V
If contrast control cannot be adequately performed by means of on-chip resistance V
be performed by inserting a resistance between VLOUT and V
Table 13.7 Contrast Control Settings
Contrast Control Register (LRA) Variable Resistance V1−V
CCR3
CCR2
CCR1
0
0
0
1
1
0
1
1
0
0
1
1
0
1
R
, is at least 0.4 V. The contrast control ranges are shown in table 13.8.
SS
CCR0
Value (V
R
0
1.6R
1
1.5R
0
1.4R
1
1.3R
0
1.2R
1
1.1R
0
1.0R
1
0.9R
0
0.8R
1
0.7R
0
0.6R
1
0.5R
0
0.4R
1
0.3R
0
0.2R
1
0.1R
13. Dot Matrix LCD Controller (H8/3857 Group)
and V1) by means of the contrast control
LCD
can be adjusted within the range of 0.1 R to 1.6 R,
.
LCD
SS
)
Difference
Small
Large
Rev.3.00 Jul. 19, 2007 page 373 of 532
and V1. The contrast
LCD
LCD
, control can
R
Potential
Display Color
Light
Dark
REJ09B0397-0300
and V1,
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