SSD1854U ETC [List of Unclassifed Manufacturers], SSD1854U Datasheet - Page 19

• Manufacturer Part Number: SSD1854U
• Description: LCD Segment / Common Driver with Controller CMOS
• Manufacturer: ETC [List of Unclassifed Manufacturers]

SSD1854
Series
7.10 Level selector
7.11 HV Buffer Cell (Level Shifter)
Level Selector is a control of the display synchronization. Display voltage can be separated into
two sets and used with different cycles. Synchronization is important since it selects the
required LCD voltage level to the HV Buffer Cell, which in turn outputs the COM or SEG LCD
waveform.
HV Buffer Cell works as a level shifter which translated the low voltage output signal to the
required driving voltage. The output is shifted out with an internal FRM clock, which comes
from the Display Timing Generator. The voltage levels are given by the level selector, which is
synchronized with the internal M signal.
For a panel with N rows and M columns, the optimal LCD driving voltage are given as:
And
where:
V
V
(The peak-to-peak Row driving voltage is given by V
V
V
(The peak-to-peak Column driving voltage is given by V
Relationship between the levels:
V
th
L7
L4
L6
L
Rev 1.0
08/2002
7
, V
is the threshold voltage of the LCD panel
is the maximum (Row) driving level with reference to V
is the middle of all driving levels
L5
V
, V
L
V
and
V
V
4
L7
CC
L
L3
6
> V
V
> V
and V
L
V
4
L6
L4
L
V
4
> V
+ 2V
L
V
L2
5
SS
V
are the other Column driving levels
L5
L
V
> V
4
L
4
V
L4
N
4
L
V
> V
2
L
4
L3
4
2
> V
V
L
V
3
N
L2
N
L
7
> V
N
V
1
L
V
SS
6
L
2
4
V
V
th
L
4
L7
-V
L6
SS
-V
)
SS
SS
)
SOLOMON
14