ICM7231 Ver la hoja de datos (PDF) - Intersil
Número de pieza
componentes Descripción
Fabricante
ICM7231 Datasheet PDF : 16 Pages
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ICM7231, ICM7232
φ1 φ2 φ3 φ1´ φ2´ φ3´
BP1
VDD
VH
VP
VL
VDISP
BP2
VDD
VH
VL
VDISP
COMMON LINE
WAVEFORMS
BP3
SEGMENT
LINE
ALL OFF
a SEGMENT
ON
a, d OFF
a, g ON
d OFF
VDD
VH
VL
VDISP
VDD
VH
VL
VDISP
VDD
VH
VL
VDISP
VDD
VH
VL
VDISP
ON CHIP
RESISTOR
STRING
VDD
~75kΩ
VH
~75kΩ
VL
~75kΩ
PIN 2
VDISP
INPUT
TYPICAL
SEGMENT LINE
WAVEFORMS
VDD
ALL ON
VH
VL
NOTES:
VDISP
1. φ1, φ2, φ3, - BP High with Respect to Segment.
2. φ1´, φ2´, φ3´, - BP Low with Respect to Segment.
3. BP1 Active during φ1, and φ1´.
4. BP2 Active during φ2, and φ2´.
5. BP3 Active during φ3, and φ3´.
FIGURE 5. DISPLAY VOLTAGE WAVEFORMS
f
BP1
SEGMENT
LINES
a
b
e
BP2
g
c
an2
BP3
d
an1
FIGURE 6. DISPLAY SCHEMATIC
VP = (V+) - VDISP
φ1 φ2 φ3 φ1´ φ2´ φ3´
+VP
ALL OFF
0
-VP
VRMS = V---3--P-- = VRMSOFF
+VP
a SEGMENT
ON
0
a, d OFF
-VP
+VP
a, g ON
d OFF
0
-VP
VRMS
=
-----1---1--
3
×
V---3--P--
=
VRMSON
+VP
ALL ON
0
-VP
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 VP/3 and that
the RMS ON voltage is always 1.92VPEAK/3.
For a 1/3 multiplexed LCD, the ratio of RMS ON to OFF
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.
Voltage Contrast Ratio
=
-V-V---R-R---M--M---S-S---O-O----F--N--F--
=
-----1---1--
3
=
1.92
NOTES:
1. φ1, φ2, φ3, - BP High with Respect to Segment.
2. φ1´, φ2´, φ3´, - BP Low with Respect to Segment.
3. BP1 Active during φ1, and φ1´.
4. BP2 Active during φ2, and φ2´.
5. BP3 Active during φ3, and φ3´.
FIGURE 7. VOLTAGE WAVEFORMS ON SEGMENT g(VG)
9-27
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