Specifications

4–18 EPSON
SED1220
Liquid crystal voltage generating circuit
V
5 potential is resistive divided within IC to produce V1,
V
2, V3 and V4 potentials required for driving the liquid
crystal. V1, V2, V3 and V4 potentials are then subject to
impedance conversion and provided to the liquid crystal
drive circuit.
The liquid crystal drive voltage is fixed to 1/5 (1/4) bias.
The liquid crystal power terminals V
1 – V5 must be
externally connected with the voltage regulating capacitor
C2.
When a built-in supply is used
When voltage is doubled
When voltage is tripled
Reference setting values: C1: 0.1 - 4.7 µF We recommend the user to set the optimum values to capacitors C1
C2: 0.1 µF and C2 according to the panel size watching the liquid crystal display
and drive waveforms.
CAP1+
CAP1–
CAP2–
V
OUT
V 5
R3
R2
R1
V
DD , V 0
C2
C2
C2
C2
C2
C2
V
1
V 2
V 3
V 4
V 5
V S1
V R
V SS
C1
SED1220D
✽✽
CAP1+
CAP1–
V
OUT
V 5
R3
R2
R1
V
DD , V 0
C2
C2
C2
C2
C2
C1
V
1
V 2
V 3
V 4
V 5
V R
V SS
SED1220D ✽✽
C1
C1
CAP2+
CAP2–
C1C1
V S1