UPD78F0411GA-GAM-AX Datasheet, PDF (408/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 15 LCD CONTROLLER/DRIVER
15.8 Supplying LCD Drive Voltages VLC0, VLC1, VLC2 and VLC3
With the 78K0/LC3, a LCD drive power supply can be generated using either of two types of methods: internal
resistance division method or external resistance division method.
15.8.1 Internal resistance division method
The 78K0/LC3 incorporates voltage divider resistors for generating LCD drive power supplies. Using internal
voltage divider resistors, a LCD drive power supply that meet each bias method listed in Table 15-9 can be generated,
without using external voltage divider resistors.
Table 15-9. LCD Drive Voltages (with On-Chip Voltage Divider Resistors)
Bias Method
LCD Drive Voltage Pin
VLC0
VLC1
VLC2
VLC3
No Bias (Static)
VLCD
2
3 ^VLCD
1
3 ^VLCD
VSS
1/2 Bias Method
VLCD
1
2
VLCD^Note
VSS
1/3 Bias Method
VLCD
2
3 ^VLCD
1
VLCD
3
VSS
1/4 Bias Method
VLCD
3
4 ^VLCD
2
VLCD
4
1
VLCD
4
Note For the 1/2 bias method, it is necessary to connect the VLC1 and VLC2 pins externally.
Figure 15-23 shows examples of generating LCD drive voltages internally according to Table 15-9.
Figure 15-23. Examples of LCD Drive Power Connections (Internal Resistance Division Method) (1/2)
(a) 1/3 bias method and static display mode
(MDSET1, MDSET0 = 0, 1)
(example of VDD = 5 V, VLC0 = 5 V)
SCOC
VDD
P-ch
VLC0
VLC1
VLC2
P40/KR0
VLC0
R
VLC1
R
VLC2
R
P40/KR0
VSS
VSS
(b) 1/3 bias method and static display mode
(MDSET1, MDSET0 = 1, 1)
(example of VDD = 5 V, VLC0 = 3 V)
SCOC
VDD
P-ch
VLC0
VLC1
VLC2
P40/KR0
2R
VLC0
R
VLC1
R
VLC2
R
P40/KR0
VSS
VSS
VLC0 = VDD
VLC0 =
3
5
VDD
Remark It is recommended to use the external resistance division method when using the static display mode, in
order to reduce power consumed by the voltage divider resistor.
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User’s Manual U18698EJ1V0UD