SSD1854U ETC [List of Unclassifed Manufacturers], SSD1854U Datasheet - Page 18

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

13
SSD1854
Series
7.8
7.9
LCD Driving Voltage Generator and Regulator
This module generates the LCD voltage needed for display output. It takes a single supply input
and generates necessary bias voltages.
288 Bit Latch
A register carries the display signal information. In 128 X 160 display-mode, data will be fed to
the HV-buffer Cell and level-shifted to the required level.
It consists of:
1.
2.
3.
4.
5.
6.
3X, 4X and 5X DC-DC voltage converter:
The booster output at V
voltage must be greater than 2V + VL4 or 2V + ½ VL7. Please refer to application notes
for details.
Voltage Regulator
Feedback gain control for initial LCD voltage. Internal resistors are connected between
V
resistors are chosen to give the desired V
Bias Divider
There is an on-chip bias divider inside the chip selected by software which generate all
V
Contrast Control
Software control of 64 voltage levels of LCD voltage.
Bias Ratio Selection circuitry
Software control of different bias ratios to match the characteristic of LCD panel.
Self adjust temperature compensation circuitry
Provide 4 different compensation grade selections to satisfy the various liquid crystal
temperature grades. The grading can be selected by software control. Defaulted
temperature coefficient (TC) value is -0.1%/°C.
SS
L2
Rev 1.0
08/2002
~V
and V
L7
OSC1
where:
levels automatically.
V
R
L
7
(internal contrast voltage reference), and between V



1
V
(1+R2/R1) is the software programmable IRS value
α is the software contrast level from 0 to 63
ref
Internal Resistor
R
Oscillation Circuit
R
is the internally generated reference voltage
2
1



CC
Figure 4 - Oscillator Circuitry
equals to n time VCI where n is the booster ration. The VCC
V
con
enable
OSCE
and
L7
according to the following equation:
enable
Buffer
Oscillator
enable
V
con
(CL)
R



and V
1
63
L7
210
. These



SOLOMON
V
ref