Specifications

4–20 EPSON
SED1220
Low Power Consumption Mode
SED1220 is provided with standby mode and sleep mode
for saving power consumption during standby period.
● Standby Mode
Switching between on and off of the standby mode is
done using the power save command.
In the standby mode, only static icon is displayed.
1. Liquid crystal display output
COM1 ~ COM24, COMS1, COMS2 : V
DD level
SEG1 ~ SEG60, SEGS1, 2, 4, 5 : V
DD level
SEGSA, B, C, D, E, F, G, H, I, J, COMSA: Can be
turned on by static drives.
Use the static icon RAM for controlling the static
icon display done with SEGSA, B, C, D, E, COMSA.
2. DD RAM, CG RAM and symbol register
Written information is saved as it is irrespective of on
or off of the stand-by mode.
3. Operation mode is retained the same as it was prior
to execution of the standby mode.
The internal circuit for the dynamic display output is
stopped.
4. Oscillating circuit
The oscillation circuit for the static display must be
remained on.
● Sleep Mode
To enter the sleep mode, turning off the power circuit and
oscillation circuit using the commands, and then execute
power save command. This mode helps to save power
consumption by reducing current to almost resting cur-
rent level.
1. Liquid crystal display output
COM1 ~ COM24, COMS1, COMS2 : V
DD level
SEG1 ~ SEG60, SEGS1, 2, 4, 5 : V
DD level
SEGSA, B, C, D, E, F, G, H, I, J, COMSA: Clear all
the data of the static icon registers to “0”.
2. DD RAM, CG RAM and symbol register
Written information is saved at it is irrespective of on
or off the sleep mode.
3. Operation mode mode is retained the same at it was
prior to execution of the sleep mode.
All internal circuits are stopped.
4. Power circuit and oscillation circuit
Turn off the built-in supply circuit and oscillation
circuit using the power save command and supply
control command.
Reset Circuit
Upon activation of the RES input, this LSI will be
initialized.
● Initial State
1. Display on/off control
C = 0 : Cursor off
B = 0 : Blink off
D = 0 : Display off
2. Power save
O = 0 : Oscillation off
PS = 0 : Power save off
3. Supply control
VC = 0 : Voltage regulation circuit off
VF = 0 : Voltage follower off
P = 0 : Amplifying circuit off
4. System setting
N2, N1 = 0 : 2 lines
S = 0 : Left-hand shift
CG = 0 : “CGRAM” blank
5. Electronic volume control
Address : 28H
Data : (0, 0, 0, 0, 0)
6. Static icon
Address : 20H
Data : (0, 0, 0, 0, 0)
Address : 21H
Data : (0, 0, 0, 0, 0)
Address : 22H
Data : (0, 0, 0, 0, 0)
Address : 23H
Data : (0, 0, 0, 0, 0)
As explained in the Section “MPU interface”, the RES
terminal connects to the reset terminal of the MPU and
initialization is being effected together with the MPU.
However, when the bus, port, etc. of the MPU maintains
high-impedance for a certain duration of time after
resetting, make the resetting input to the SED1220 after
the inputs to the SED1220 have become definite.
As the resetting signal, like explained in the Section “DC
characteristics”, active level pulses of minimum 10us or
more should be used. Normal operation status can be
obtained after 1us from the edge of the RES signal.
By making the RES terminal active, respective registers
can be cleared and the aforesaid setting state can be
obtained.
If initialization is not effected by the RES terminal when
the supply voltage is applied, it may go into a state where
cancellation is unworkable.
In case the built-in liquid crystal power circuit will not be
used, it becomes necessary that the RES input be active
when the external liquid crystal power is being applied.