Fujitsu F2MC-8FX Hardware Manual page 450

CHAPTER 24 LCD CONTROLLER
Use of Internal Divider Resistors and Brightness Control
When internal divider resistors are used on a 3V model, the internal 2R resistor reduces the V1,
V2, and V3 voltages accordingly. Figure 24.2-3 shows the case when the internal divider resistors
are used.
If sufficient brightness is not achieved with the internal divider resistors in use, connect a variable
resistor (VR) externally (between the Vcc and V3 pins) to adjust the V3 voltage. Figure 24.2-4
shows an example of connecting a VR to internal divider resistors for brightness control.
Figure 24.2-4 Brightness Control with Internal Divider Resistors Used
As the internal 2R resistor is enabled during LCD operation, connect the VR resistor in parallel with
the 2R resistor.
436
Figure 24.2-3 States with Internal Divider Resistors Used
*
Vcc
2R
V3
V
3
R
5V product
V2
V
2
R
V1
V
1
R
LCDC enabled
N-ch
1/2 bias
V to V : Voltages at V1 to V3 pins
1 3
*: 3V product only. In case of the 5V product, a voltage must be supplied to the V3 pin.
3V product
2R
V
3
R
V
2
R
V
1
R
LCDC enabled
N-ch
For brightness control
V to V : Voltages at V1 to V3 pins
1 3
*
Vcc
2R
V3
V
3
R
5V product
V V2
2
R
V V1
1
R
LCDC enabled
N-ch
1/3 bias
5V product
Vcc
VR
V3
V
3
V2 V
2
V1 V
1
LCDC enabled
For brightness control
VR
V3
R
V2
R
V1
R
N-ch