13. Dot Matrix LCD Controller (H8/3857 Group)
Rev.3.00 Jul. 19, 2007 page 363 of 532
REJ09B0397-0300
•
By changing step-up circuit reference voltage V
ci
The step-up circuit voltage level can be varied by changing step-up circuit reference voltage
V
ci
.
External Power Supply
•
When an external power supply is input to V
LCD
V1 to V5 can be generated by inputting an external power supply to V
LCD
, and using the built-in
op-amps by setting the OPON bit in control register 2 (LR1) to 1. The V
LCD
input level must be
between V
CC
and 7.0 V.
•
When external power supply is input directly to V1 to V5
A power supply can be applied directly to V1, V2, V3, V4, and V5 from an external source by
clearing the PWR bit in control register 1 (LR0) and the OPON bit in control register 2 (LR1)
to 0, to halt the built-in step-up circuit and cut the built-in op-amp power supply. The same
potential as V1 should be input to V
LCD
. Apply a voltage not exceeding V
LCD
to V2 through V5.
The input level of V
LCD
and V1 must be between V
CC
and 7.0 V.
In either case, inputting a voltage exceeding the maximum rated voltage may adversely affect the
reliability of the chip.
13.3.12 LCD Drive Power Supply Voltages
There are six LCD drive power supply voltage values
⎯
V1 to V5, and V
SS
. V1 is the highest
voltage, and V
SS
the lowest. As shown in figure 13.14, the common waveforms are formed from a
combination of V1, V2, V5, and V
SS
, while the segment waveforms are formed from a
combination of V1, V3, V4, and V
SS
. V1 and V
SS
are shared by both common and segment
waveforms, but the intermediate voltages are different.
In figure 13.14, the waveforms of outputs SEG1 to SEG40 differ according to the display data. In
this example, LCD panel lines for which COM1 is connected are illuminated, and all other dots
are not illuminated.
Содержание F-ZTAT H8 Series
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