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* Precautions when installing the COG
When installing the COG, it is necessary to duly consider the fact that there exists a resistance of the ITO wiring occurring
between the driver chip and the externally connected parts (such as capacitors and resistors). By the influence of this
resistance, non-conformity may occur with the indications on the liquid crystal display.
Therefore, when installing the COG design the module paying sufficient considerations to the following three points.
1.
Suppress the resistance occurring between the driver chip pin to the externally connected parts as much as possible.
2.
Suppress the resistance connecting to the power supply pin of the driver chip.
3.
Make various COG module samples with different ITO sheet resistance to select the module with the sheet resistance
with sufficient operation margin.
Also, as for this driver IC, pay sufficient attention to the following points when connecting to external parts for the
characteristics of the circuit.
1.
Connection to the boosting capacitors The boosting capacitors (the capacitors connecting to respective CAP pins and
capacitor being inserted between V
low ON-resistance of about 10Ω. However, when installing the COG, the resistance of ITO wiring is being inserted
in series with the switching transistor, thus dominating the boosting ability.
Consequently, the boosting ability will be hindered as a result and pay sufficient attention to the wiring to respective
boosting capacitors.
2.
Connection of the smoothing capacitors for the liquid crystal drive
The smoothing capacitors for the liquid crystal driving potentials (V
crystal drives not only for the purpose of mere stabilization of the voltage levels. If the ITO wiring resistance which
occurs pursuant to installation of the COG is supplemented to these smoothing capacitors, the liquid crystal driving
potentials become unstable to cause non-conformity with the indications of the liquid crystal display. Therefore,
when using the COG module, we definitely recommend to connect reinforcing resistors externally.
Reference value of the resistance is 100kΩ to 1MΩ.
Meanwhile, because of the existence of these reinforcing resistors, current consumption will increase.
Indicated below is an exemplary connection diagram of external resistors.
Please make sufficient evaluation work for the display statuses with any connection tests.
Exemplary connection diagram 1.
V
DD
R
R
4
C
2
C
2
C
2
C
2
R
R
4
4
C
2
Rev.2.1
and V
OUT
SS2
V
DD
4
V
1
V
2
V
3
V
4
V
5
) of this IC are being switched over by use of the transistor with very
. V
1
Exemplary connection diagram 2.
V
DD
C
C
C
C
C
EPSON
S1D10605 Series
, V
and V
) are indispensable for liquid
2
3
4
V
DD
V
1
2
R
4
V
2
2
V
3
2
R
4
V
4
2
V
5
2
35
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