Lcd Drive Power - Epson S1D16000 Series Technical Manual

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
and V to drive the LCD using the voltage follower with an operational amplifier. In taking into
DD
consideration of such a case using the operational amplifier, the maximum potential level V
has been made a separate pin from V
When the potential of V
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
When no operational amplifier is used, connect V
When a series resistance exists in the power supply line of V
at the LSI power supply pin, the relationship with the LCD's intermediate potential (V
≥ V
) cannot be met, this causing the LSI to be broken down in some cases. When a protection resistor is
5
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
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
At power OFF .. LCD driving system OFF
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
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cell.
Until the LCD driver voltage stabilizes. It is recommended to set the LCD driver output potential to V
the display off function (DSPOFF).
Power ON/OFF sequence when S1D16006D01
V
DD
V
SS
V
5
V
DD
DSPOFF V
SS
Rev.2.1
.
DD
lowers than that of V
0
V
t1
Power ON
t3
and the potential difference between the two becomes larger,
DD
.
DD
and V close to the IC chip.
0 DD
and V
5 DD
SS
→LCD driving system ON or simultaneous ON of the both
→Logic system OFF or simultaneous OFF of the both
is used
**
t3
EPSON
S1D16006 Series
for LCD driving
0
, a voltage drop of V and V
5
≥ V0 ≥ V2 ≥ V3
DD
= –2.6 V, and when the LCD driving
t2
t1.t2.t3 0 sec
Power OFF
5
occurs
DD
using
0
>
=
1–13