Datasheet
RL78/L12 CHAPTER 14 LCD CONTROLLER/DRIVER
R01UH0330EJ0200 Rev.2.00 633
Dec 13, 2013
14.8 Supplying LCD Drive Voltages VL1, VL2, VL3, and VL4
The power supply voltages for the LCD driver can be produced through external resistance division, internal voltage
boosting, or capacitor split.
14.8.1 External resistance division method
Figure 14-22 shows examples of LCD drive voltage connection, corresponding to each bias method.
Figure 14-22. Examples of LCD Drive Power Connections (External Resistance Division Method)
(a) Static display mode (b) 1/2 bias method
VL4
VL4
VL3
VL2
VSS
VDD
VSS
VL3/P125
Note 2
VL2
Note 1
VL1
VL1
Note 1
VL4 = VDD
V
L4
V
L4
V
L3
V
L2
V
SS
V
DD
V
SS
V
L3
/
P125
Note 2
V
2
V
L1
R
R
V
L4
= V
DD
V
L1
(c) 1/3 bias method (d) 1/4 bias method
VL4
VL4
P125
V
L2
VSS
VDD
VSS
VL3/
P125
Note 2
VL2
R
R
VL4 = VDD
VL1
VL1
R
V
L4
V
L4
V
L3
V
L2
V
SS
V
DD
V
SS
V
L3
/
P125
Note 2
V
L2
R
R
V
L4
= V
DD
R
V
L1
V
L1
R
Notes 1. Connect V
L1 and VL2 to GND or leave open.
2. V
L3 can be used as port (P125).