CHAPTER 3 LCD CONTROLLER/DRIVER
User’s Manual U18438EJ2V0UD
49
3.9.3 Internal voltage boosting method
A booster circuit (
×
3 only) to generate a supply voltage to drive the LCD is contained. The internal LCD reference
voltage is output from the V
LC2
pin. A voltage two times higher than that on V
LC2
is output from the V
LC1
pin and a
voltage three times higher than that on V
LC2
is output from the V
LC0
pin.
The LCD reference voltage (V
LC2
) can be specified by setting LCD boost control register 0 (VLCG0).
An external capacitor (0.47 to 1
µ
F: recommended) is required when the internal voltage boosting method is
selected.
Table 3-11. Output Voltages of V
LC0
to V
LC2
Pins
VLCG0
GAIN = 0
GAIN = 1
LCD drive power supply pin
V
LC0
4.5 V
3.0 V
V
LC1
3.0 V
2.0 V
V
LC2
(LCD reference voltage)
1.5 V
1.0 V
Cautions
1. When using the LCD function, do not leave the V
LC0
, V
LC1
, and V
LC2
pins open. Refer to
Figure 3-27 for connection.
2. Since the LCD drive voltage is separate from the main power supply, a constant voltage
can be supplied regardless of LV
DD
fluctuation.
Figure 3-27. Example of Connecting Pins for LCD Driver
C2
C3
C4
CAPH
C1
External pin
C1 = C2 = C3 = C4 = 0.47 F
CAPL
µ
V
LC0
V
LC1
V
LC2
Remark
Use a capacitor with as little leakage as possible.
In addition, make C1 a nonpolar capacitor.