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13. Dot Matrix LCD Controller (H8/3857 Group)
When Using Built-In Step-Up Circuit and Bleeder Resistances
If the drive capability of the built-in op-amps is insufficient for the size of the LCD panel, the V1
to V5 levels can be supplied from external bleeder resistances. In this case, clear the OPON bit in
control register 2 (LR1) to 0 to turn the op-amps off. The built-in contrast control circuit cannot be
used, so contrast control must be handled by an external circuit.
A 1/4 or 1/5 bias value can be set, according to the method of connecting the external bleeder
resistances. Figure 13.18 shows an example of the connections for 1/5 bias drive.
The 2X or 3X step-up circuit can be used.
Rev.3.00 Jul. 19, 2007 page 371 of 532
REJ09B0397-0300
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