LCD Driver Technical Manual

SED1520 Series
2–10 EPSON
Common Timing Generator Circuit
Generates common timing signals and FR frame signals
from the CL basic clock. The 1/16 or 1/32 duty (for
SED1520) or 1/8 or 1/16 duty (for SED1522) can be
selected by the Duty Select command. If the 1/32 duty is
selected for the SED1520 and 1/16 duty is selected for the
SED1522, the 1/32 and 1/16 duties are provided by two
chips consisting of the master and slave chips in the
common multi-chip mode.
SED1520
012 1415 01 15
16 17 30 31
16 17 31
FR signal
(Master output)
Master Common
Slave Common
SED1522
012 67 01 7
8 9 14 15
89 15
FR signal
(Master output)
Master Common
Slave Common
Display Data Latch Circuit
This latch stores one line of display data for use by the
LCD driver interface circuitry. The output of this latch
is controlled by the Display ON/OFF and Static Drive
ON/OFF commands.
LCD Driver Circuit
The LCD driver circuitry generates the 80 4-level signals
used to drive the LCD panel, using output from the
display data latch and the common timing generator
circuitry.
Display Timing Generator
This circuit generates the internal display timing signal
using the basic clock, CL, and the frame signals, FR.
FR is used to generate the dual frame AC-drive wave-
form (type B drive) and to lock the line counter and
common timing generator to the system frame rate.
CL is used to lock the line counter to the system line scan
rate. If a system uses both SED1520s or SED1522 and
SED1521s they must have the same CL frequency rating.