ICM7232 Intersil Corporation, ICM7232 Datasheet - Page 9

• Manufacturer Part Number: ICM7232
• Description: Numeric/alphanumeric Triplexed Lcd Display Drivers
• Manufacturer: Intersil Corporation

NOTES:
The degree of polarization of the liquid crystal material and
thus the contrast of any intersection depends on the RMS
voltage across the intersection capacitance. Note from
Figure 7 that the RMS OFF voltage is always V
the RMS ON voltage is always 1.92V
For a
voltages is fixed at 1.92, achieving adequate display contrast
with this ratio of applied RMS voltage makes some demands
on the liquid crystal material used.
a
1.
2.
3. BP1 Active during 1, and 1´.
4. BP2 Active during 2, and 2´.
5. BP3 Active during 3, and 3´.
SEGMENT
SEGMENT
ALL OFF
a
a
ALL ON
,
1, 2, 3, - BP High with Respect to Segment.
1´, 2´, 3´, - BP Low with Respect to Segment.
d
,
d OFF
g
LINE
1
BP1
BP2
BP3
OFF
ON
ON
/
3
FIGURE 5. DISPLAY VOLTAGE WAVEFORMS
multiplexed LCD, the ratio of RMS ON to OFF
1
2
3
1´
2´
3´
PEAK
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
DD
H
L
DISP
DD
H
L
DISP
DD
H
L
DISP
DD
H
L
DISP
DD
H
L
DISP
DD
H
L
DISP
DD
H
L
DISP
/3.
COMMON LINE
WAVEFORMS
TYPICAL
SEGMENT LINE
WAVEFORMS
V
PIN 2
P
DISP
V
ICM7231, ICM7232
V
~
~
~
/3 and that
V
DD
V
P
75k
H
75k
75k
L
RESISTOR
ON CHIP
STRING
INPUT
9-27
NOTES:
Voltage Contrast Ratio
1.
2.
3. BP1 Active during 1, and 1´.
4. BP2 Active during 2, and 2´.
5. BP3 Active during 3, and 3´.
FIGURE 7. VOLTAGE WAVEFORMS ON SEGMENT g(V
1, 2, 3, - BP High with Respect to Segment.
1´, 2´, 3´, - BP Low with Respect to Segment.
a SEGMENT
ALL OFF
a, d OFF
ALL ON
a, g ON
BP1
BP2
BP3
d OFF
FIGURE 6. DISPLAY SCHEMATIC
ON
an
V
e
2
f
V
RMS
RMS
=
1
VP = (V+) - VDISP
----------------------------- -
V
V
=
RMS
RMS
2
=
----------
a
g
d
VP
------- -
11
3
3
OFF
3
ON
=
VP
------- -
3
1´
V
=
b
c
an
RMS
=
----------
1
2´
11
SEGMENT
LINES
3
V
OFF
RMS
=
3´
1.92
ON
+VP
0
-VP
+VP
0
-VP
+VP
0
-VP
+VP
0
-VP
G
)