Fig. 14.6 State When External Split Resistors Used - Fujitsu MB90420/5 (A) Series Hardware Manual

„
Using external split resistors
The V0 pin is connected to Vss (GND) via an internal transistor. Consequently, when using external split
resistors, the current passing through the resistors at stopping the LCD controller can be cut by connecting
the Vss side of the external split resistors to only the V0 pin.
Figure 14.6 shows the state when external split resistors are used.
• To connect external split resistors without being affected by internal split resistors, 0 must be written to the
LCDC control register driving power control bit (LCRL: VSEL), to isolate all the internal split resistors.
• When all the internal split resistors are isolated, when a value other than 00
register display mode select bits (LCRL: MS1, MS0), the LCDC enable transistor (Q1) is set to ON, and
current passes through the external split resistors.
• When 00
is written to the display mode select bits (MS1, MS0), the LCDC enable transistor (Q1) is set to
B
OFF and current does not pass through the external split resistors.
Note: The externally connected RX depends on the LCD, so select an appropriate value for RX.
LCD CONTROLLER/DRIVER
V
3
V
2
V
1
V
0
LCD controller
enabled

Fig. 14.6 State when External Split Resistors Used

V
CC
V
3
V
R
2
V
R
1
V
R
0
V
0
Q1
14-9
VR
RX
RX
RX
= V
SS
is written to the LCDC control
B