S3C8245/P8245/C8249/P8249 LCD CONTROLLER/DRIVER
14-7
LCD DRIVE VOLTAGE
The LCD display is turned on only when the voltage difference between the common and segment signals is greater
than VLCD. The LCD display is turned off when the difference between the common and segment signal voltages is
less than VLCD. The turn-on voltage, + VLCD or - VLCD, is generated only when both signals are the selected signals
of the bias. Table 14-7 shows LCD drive voltages for static mode, 1/2 bias, and 1/3 bias.
Table 14-6. LCD Drive Voltage Values
LCD Power Supply Static Mode 1/2 Bias 1/3 Bias
VLC2 VLCD VLCD VLCD
VLC1 –VLCD 2/3 VLCD
VLC0 –1/2 VLCD 1/3 VLCD
Vss 0 V 0 V 0 V
NOTE: The LCD panel display may deteriorate if a DC voltage is applied that lies between the common and segment
signal voltage. Therefore, always drive the LCD panel with AC voltage.
LCD SEG/SEG SIGNALS
The 32 LCD segment signal pins are connected to corresponding display RAM locations at 00H–0FH.
Bits 0-3 (and 4-7) of the display RAM are synchronized with the common signal output pins COM0, COM1, COM2,
and COM3.
When the bit value of a display RAM location is "1", a select signal is sent to the corresponding segment pin. When
the display bit is "0", a 'no-select' signal is sent to the corresponding segment pin. Each bias has select and no-
select signals.
COM-SEG
FR
Select Non-Select
1 Frame
COM
SEG
V
LC2
V
SS
V
LC2
V
SS
V
LC2
V
SS
-V
LC2
Figure 14-4. Select/No-Select Bias Signals in Static Display Mode