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5 PERIPHERAL CIRCUITS AND THEIR OPERATION (LCD Controller)
5.11.3 LCD power supply
Either the internal power supply (built-in LCD
system voltage regulator and voltage booster/
reducer) or an external power supply can be
selected by mask option to generate the LCD
system drive voltages V
Furthermore, the internal power supply can be
selected from among four types, TYPE A to TYPE
D, according to the LCD panel characteristics.
LCD power supply
Internal power supply TYPE A (V
Internal power supply TYPE B (V
Internal power supply TYPE C (V
Internal power supply TYPE D (V
External power supply
The internal power supply is designed for a small
scale LCD panel and is not suitable for driving a
panel that has large size pixels or for driving a large
capacity panel using an external expanded LCD
driver. In this case, select external power supply
and input the regulated voltage from outside the
IC.
Note that the LCD must be driven with 1/5 bias
when external power supply is selected.
Figure 5.11.3.1 shows the circuit examples when
using an external power supply.
V
IN
V
C5
V
C4
V
C3
V
C2
V
C1
Rxx
V
SS
* V
level or high impedance when LCD is not driven.
SS
Fig. 5.11.3.1 Circuit examples when using
an external power supply
Table 5.11.4.1 Correspondence between drive duty and maximum number of displaying dots
Model
E0C88832
E0C88862
90
–V
.
C1
C5
standard, 1/5 bias, 4.5 V)
C2
standard, 1/5 bias, 5.5 V)
C2
standard, 1/4 bias, 4.5 V)
C2
standard, 1/4 bias, 4.5 V)
C1
V
*
IN
V
C5
V
C4
V
C3
V
C2
V
C1
V
SS
Mask option
LDUTY
0
1/32 & 1/16 duty
1
×
1/8 duty
0
1/32 & 1/16 duty
1
×
1/8 duty
5.11.4 LCD driver
The maximum number of dots changes according
to the drive duty selection.
When 1/32 duty is selected, the combined com-
mon/segment output terminal is switched to the
common terminal. An LCD panel with 51 segments
× 32 commons (maximum 1,632 dots) in the
E0C88832 and 41 segments × 32 commons
(maximum 1,312 dots) in the E0C88862 can be
driven.
When 1/16 duty is selected, the combined com-
mon/segment output terminal is switched to the
segment terminal. An LCD panel with 67 segments
× 16 commons (maximum 1,072 dots) in the
E0C88832 and 57 segments × 16 commons
(maximum 912 dots) in the E0C88862 can be driven.
When 1/8 duty is selected, the combined common/
segment output terminal is switched to the segment
terminal as when 1/16 duty is selected. An LCD
panel with 67 segments × 8 commons (maximum
536 dots) in the E0C88832 and 57 segments × 8
commons (maximum 456 dots) in the E0C88862 can
be driven. Furthermore, when 1/8 duty is selected,
terminals COM8–COM15 become invalid, in that
they always output an OFF signal.
Table 5.11.4.1 shows the correspondence between
the drive duty and the maximum number of
displaying dots.
Figures 5.11.4.1 to 5.11.4.3 show the 1/5 bias drive
waveforms.
When driving with 1/4 bias, the V
the same as V
.
C3
Common
Duty
terminal
1/32
COM0–COM31
1/16
COM0–COM15
1/8
COM0–COM7
1/32
COM0–COM31
1/16
COM0–COM15
1/8
COM0–COM7
EPSON
voltage level is
C2
Segment
Maximum number
terminal
of display dots
SEG0–SEG50
1,632 dots
SEG0–SEG66
1,072 dots
536 dots
SEG0–SEG40
1,312 dots
SEG0–SEG40
912 dots
SEG51–SEG66
456 dots
E0C88832/88862 TECHNICAL MANUAL
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