S1D16006 Series
Rev.2.1
EPSON
1–13
11. LCD DRIVE POWER
Each voltage level forming method
To obtain each voltage level for LCD driving, it is optimum to divide the resistance of potential between V
5
and V
DD
to drive the LCD using the voltage follower with an operational amplifier. In taking into
consideration of such a case using the operational amplifier, the maximum potential level V
0
for LCD driving
has been made a separate pin from V
DD
.
When the potential of V
0
lowers than that of V
DD
and the potential difference between the two becomes larger,
however, the capacity of LCD drive output driver lowers. To avoid it, use the system with the potential
difference of 0 V to 2.5 V between V0 and V
DD
.
When no operational amplifier is used, connect V
0
and V
DD
close to the IC chip.
When a series resistance exists in the power supply line of V
5
and V
DD
, a voltage drop of V
5
and V
DD
occurs
at the LSI power supply pin, the relationship with the LCD’s intermediate potential (V
DD
≥
V0
≥
V2
≥
V3
≥
V
5
) cannot be met, this causing the LSI to be broken down in some cases. When a protection resistor is
inserted, it is necessary to stabilize the voltage by capacitance.
Note in power ON/OFF
Since this LSI is high in the voltage of LCD driving system, when a high voltage is applied to the LCD driving
system with the logic system power supply kept floating or above V
SS
= –2.6 V, and when the LCD driving
signal is output before the applied voltage to the LCD driving system is stabilized, an overcurrent flows and
LSI breaks down in some cases.
Be sure to follow the power ON/OFF sequence as shown below:
At power ON ... Logic system ON
→
LCD driving system ON or simultaneous ON of the both
At power OFF .. LCD driving system OFF
→
Logic system OFF or simultaneous OFF of the both
For a countermeasure to such overcurrent, it is effective to put a high-speed melting fuse or protection resistor
in series with the LCD power unit.
It is then required to select the optimum value in the protection resistance according to the capacitance of LC
cell.
Until the LCD driver voltage stabilizes. It is recommended to set the LCD driver output potential to V
0
using
the display off function (DSPOFF).
Power ON
Power OFF
t1.t2.t3 0 sec
t2
>
=
t1
V
V
DD
Power ON/OFF sequence when S1D16006D01
**
is used
V
DD
V
SS
V
SS
DSPOFF
V
5
t3
t3
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Содержание S1D16000 Series
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