HD44780U Datasheet, PDF (37/59 Pages) Hitachi Semiconductor – Dot Matrix Liquid Crystal Display Controller/Driver

HD44780U
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 Duty Factor and Power Supply for Liquid Crystal Display Drive
Power Supply
V1
V2
V3
V4
V5
1/8, 1/11
1/4
V_CC–1/4 VLCD
V_CC–1/2 VLCD
V_CC–1/2 VLCD
V_CC–3/4 VLCD
V_CC–VLCD
Duty Factor
1/16
Bias
1/5
V_CC–1/5 VLCD
V_CC–2/5 VLCD
V_CC–3/5 VLCD
V_CC–4/5 VLCD
V_CC–VLCD
V_CC (+5 V)
V_CC
R
V1
V2
R
VLCD
V3
R
V4
R
V5
1/4 bias
(1/8, 1/11 duty cycle)
VR
–5 V
V_CC
V1
V2
V3
V4
V5
1/5 bias
(1/16, duty cycle)
V_CC (+5 V)
R
R
R ^VLCD
R
R
VR
–5 V
Figure 21 Drive Voltage Supply Example
37