ST7565
3. When the V/F circuit alone is used
4. When the built-in power is not used
VDD
IRS
M/S
VSS2
VSS
VOUT
CAP3-
CAP1+
CAP1-
External
power
supply
CAP2+
CAP2-
V5
VR
VDD
VDD
C2
V1
C2
V2
C2
V3
C2
V4
C2
V5
5. When the built-in power circuit is used to drive a liquid
crystal panel heavily loaded with AC or DC, it is
recommended to connect an external resistor to stabilize
potentials of V1, V2, V3 and V4 which are output from the
built-in voltage follower.
VDD,V0
R4
R4
C2
V1
V2
V3
V4
VSS
IRS
VDD
External power supply
VSS2
VOUT
CAP3-
CAP1+
CAP1-
CAP2+
CAP2-
V5
VR
VDD
V1
V2
V3
V4
V5
VDD
M/S
Examples of shared reference settings When V5 can vary
between –8 and 12 V
Item
C1
C2
Set value
1.0 to 4.7
0.1 to 4.7
Units
uF
uF
C1 and C2 are determined by the size of
the LCD being driven
R4
R4
V5
Reference set value R4: 100KΩ ~ 1MΩ It is recommended resistance value R4 taking the liquid crystal display and the
to set an optimum
drive waveform.
Figure 15
* 1. Because the VR terminal input impedance is high, use short leads and shielded lines.
* 2. C1 and C2 are determined by the size of the LCD being driven. Select a value that will stabilize the liquid crystal
drive voltage.
Example of the Process by which to Determine the Settings:
• Turn the voltage regulator circuit and voltage follower circuit ON and supply a voltage to VOUT from the outside.
• Determine C2 by displaying an LCD pattern with a heavy load (such as horizontal stripes) and selecting a C2 that
stabilizes the liquid crystal drive voltages (V1 to V5). Note that all C2 capacitors must have the same capacitance
value.
• Next turn all the power supplies ON and determine C1.
Ver 1.0a
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2002/06/24