Specifications
SED1220
EPSON 4–33
SED1220
*5: Character “ ” display. This is applicable to the
case where no access is made from the MPU and the
built-in power circuit and oscillating circuit are in
operation.
*6: Current consumption when data is always written by
f
cyc.
The current consumption in the access state is almost
proportional to the access frequency (f
cyc).
When no access is made, only I
DD (I) occurs.
*7:
tR (reset time) indicates the internal circuit reset
completion time from the edge of the RES signal.
Accordingly, the SED1220 usually enters the oper-
ating state after
tR.
*8: Specifies the minimum pulse width of the RES
signal. It is reset when a signal having the pulse
width greater than tRW is entered.
*9: When operating the boosting circuit, the power
supply V
SS must be used within the input voltage
range.
*10:The f
OSC frequency of the oscillator circuit for
internal circuit drive may differ from the fBST boost-
ing clock on some models. The following provides
the relationship between the f
OSC frequency, fBST
boosting clock, and fFR frame frequency.
f
OSC = (No. of digits) × (1/Duty) × fFR
fBST = (1/2) × (1/No. of digits) × fOSC
*11:When performing the operations using an external
clock, not taking advantage of the built-in oscillation
circuit, input the waveforms indicated below.
Meanwhile, while using an external clock but when
clock inputs are not being made, fix it to “H”.
(Normal High)
<Incase the external clock = fosc>
• Duty = (t
h/tosc) × 100 = 20 ~ 30%
• fosc = 1/tosc
<Incase the external clock = 4 × fosc>
• Duty = (t
h/tosc) × 100 = 50%
• fosc = 1/tosc
Power Supply
t
RES
V
DD
V
SS
V
DD
V
SS
–2.4 V
t
RW
t
R
RES
All signal timings are based on 20% and 80% of V
SS
signals.
t
osc
t
osc
t
h
t
h