UPD78F1502AGK-GAK-AX Datasheet, PDF (720/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 16 LCD CONTROLLER/DRIVER
Figure 16-31. Examples of LCD Drive Power Connections (External Resistance Division Method) (2/2)
(c) 1/3 bias method
(d) 1/4 bias method
VLC0
VLC1
VLC2
VLC3
VSS
VDD
VLC0
R
VLC1
R
VLC2
R
VLC3/
P02^Note
VSS
VLC0
VLC1
VLC2
VLC3
VSS
VDD
VLC0
R
VLC1
R
VLC2
R
VLC3
R
VSS
VLC0 = VDD
Note VLC3 can be used as port (P02).
VLC0 = VDD
Caution To stabilize the potential of the VLC0 to VLC3 pins, it is recommended to connect a capacitor of
about 0.1 μF between each of the pins from VLC0 to VLC3 and the GND pin as needed.
16.8.2 Internal voltage boosting method
The 78K0R/Lx3 microcontrollers contain an internal voltage boost circuit for generating LCD drive power supplies. The
internal voltage boost circuit and external capacitors (0.47 μF±30%) are used to generate an LCD drive voltage. Only 1/3
bias mode or 1/4 bias mode can be set for the internal voltage boost method.
The LCD drive voltage of the internal voltage boost method can supply a constant voltage, regardless of changes in
VDD, because it is a power supply separate from the main unit.
In addition, a contrast can be adjusted by using the LCD boost level control register (VLCD).
Table 16-10. LCD Drive Voltages (Internal Voltage Boosting Method)
Bias Method
LCD Drive Voltage Pin
1/3 Bias Method
VLC0
VLC1
VLC2
VLC3
3 x VLC2
2 x VLC2
LCD reference voltage
−
1/4 Bias Method
4 x VLC3
3 x VLC3
2 x VLC3
LCD reference voltage
R01UH0004EJ0501 Rev.5.01
704
Jun 20, 2011