HD44780 Hitachi Semiconductor (acquired by Renesas), HD44780 Datasheet - Page 37

• Manufacturer Part Number: HD44780
• Description: Dot Matrix Liquid Crystal Display Controller/driver
• Manufacturer: Hitachi Semiconductor (acquired by Renesas)

Power Supply for Liquid Crystal Display Drive
Various voltage levels must be applied to pins V1 to V5 of the HD44780U to obtain the liquid crystal
display drive waveforms. The voltages must be changed according to the duty factor (Table 10).
VLCD is the peak value for the liquid crystal display drive waveforms, and resistance dividing provides
voltages V1 to V5 (Figure 21).
Table 10
Power Supply
V1
V2
V3
V4
V5
1/4 bias
(1/8, 1/11 duty cycle)
Duty Factor and Power Supply for Liquid Crystal Display Drive
V
V1
V2
V3
V4
V5
CC
Figure 21 Drive Voltage Supply Example
V
1/8, 1/11
1/4
V
V
V
V
V
CC
CC
CC
CC
CC
CC
–5 V
–1/4 VLCD
–1/2 VLCD
–1/2 VLCD
–3/4 VLCD
–VLCD
(+5 V)
R
R
R
R
VR
VLCD
1/5 bias
(1/16, duty cycle)
Duty Factor
1/16
Bias
1/5
V
V
V
V
V
V
V1
V2
V3
V4
V5
CC
CC
CC
CC
CC
CC
–1/5 VLCD
–2/5 VLCD
–3/5 VLCD
–4/5 VLCD
–VLCD
V
CC
–5 V
(+5 V)
VR
R
R
R
R
R
HD44780U
VLCD
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