M38203M4 Datasheet, PDF (50/344 Pages) Mitsubishi Electric Semiconductor – 8-BIT SINGLE-CHIP MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS
3820 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
Bias Control and Applied Voltage to LCD
Power Input Pins
To the LCD power input pins (VL1–VL3), apply the voltage shown in
Table 3 according to the bias value.
Select a bias value by the bias control bit (bit 2 of the LCD mode
register).
Common Pin and Duty Ratio Control
The common pins (COM0–COM3) to be used are determined by
duty ratio.
Select duty ratio by the duty ratio selection bits (bits 0 and 1 of the
LCD mode register).
Table 9. Bias control and applied voltage to VL1–VL3
Bias value
Voltage value
1/3 bias
1/2 bias
VL3=VLCD
VL2=2/3 VLCD
VL1=1/3 VLCD
VL3=VLCD
VL2=VL1=1/2 VLCD
Note 1 : VLCD is the maximum value of supplied voltage for the
LCD panel.
Table 10. Duty ratio control and common pins used
Duty
ratio
2
3
4
Duty ratio selection bit
Bit 1
Bit 0
0
1
1
0
1
1
Common pins used
COM0, COM1 (Note 1)
COM0–COM2 (Note 2)
COM0–COM3
Notes 1 : COM2 and COM3 are open
2 : COM3 is open
Contrast control
VL3
R1
VL2
R2
VL1
R3
1/3 bias
R1 = R2 = R3
Fig. 32 Example of circuit at each bias
Contrast control
VL3
R4
VL2
VL1
1/2 bias
R5
R4 = R5
1-34
3820 GROUP USER’S MANUAL