HD66766R Datasheet, PDF (72/97 Pages) Hitachi Semiconductor – 132 x 176-dot Graphics LCD Controller/Driver for 65K Colors

HD66766R
Rev. 1.0-1 / September 2002
LCD Voltage Generation Circuit
Figure 58 shows a configuration of the HD66766R LCD drive voltage generation circuit. It consists of
step-up circuit 1 that doubles or triples the voltage that is applied to Vci1, step-up circuit 2 that multiplies
the voltage from step-up circuit 1 by two to five times, and polarity circuit that generates a VCL level by
inverting the VCH level centered around the VM level. These circuits generate VCH and VCL that are
power supply for COM outputs. The LCD driving level for SEG outputs (VSH and VM) are generated by
dividing resistance at the VREF level.
Vcc
VREF Control
+ Amplifier
bias
VREFL _-
amplifier
+
-
BIASC
+
Vci2
1.0µF
-
VREFM
Vcc
1.0µF
1.0µF
1.0µ F
1.0µF
VciOUT _{Vci Control}
Circuits
Vci1
C11-
C11+
VOUT
generator
C12-
C12+
Step - up
circuits 1
VOUT
bias control
C21-
VCH
Generator
Step - up
circuits 2
C21+
C22-
C22+
C23-
C23+
C24-
C24+
Contrast
control
+
-
+
-
VCH
VSH
VM
1.0µF
1.0µF
1.0µF
1.0µF
1.0µF
1.0µF
1.0MΩ
1.0µF
AVcc
Vcc
GND
AGND
SEG driver
COM driver
HD66766R
VCL
generator
Polarity
inverting
circuit
VCL
CEM
CEP
1.0µF
Shot-key
barrier diode
0.47uF
Figure 55 Configuration of internal power circuit
Note:
1) Use condenser with character B.
2) Condensers with asterisk (*) need resist
pressure more than 25V.
3) Insert shot-key barrier diode.
(VF = 0.6V / 20mA, VR>=30V)
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