UPD16680 datasheet(13/44 Pages) NEC

13 / 44 page

Data Sheet S12694EJ2V0DS00

µµµµPD16680

5.3 REFERENCE VOLTAGE CIRCUIT

5.3.1 To use internal reference voltage circuit ( VEXT = L )

When internal driving circuit is chosen, 6 levels for LCD reference voltage (VLC1, VLC2, VLC3, VLC4, VLC5, VSS) is

generate by internal breeder resister.

5.3.2 To use external driving circuit ( VEXT = H )

When external driving circuit is chosen, operational amplifier incorporated IC is Off. It is necessary to input voltage

to VLC1, VLC2, VLC3, VLC4 and VLC5 directly.

Generally, These levels are made by external breeder resister. The display dignity of LCD declines when these

resistance values are big, it is necessary to choose the resistance value which corresponds with the LCD panel.

There is an effect that improves display dignity when connecting a capacitor with each level pins and the ground. It is

necessary to choose the condenser value which corresponds with the LCD panel.

Figure 5-3. Reference voltage circuit

VLC1

to SEG, COM Outputs

VLC2

to COM Output

VLC3

to SEG Output

VLCBS3

VLCBS2

VLC4

to SEG Output

VLC5

−

to COM Output

AMPOUT

to SEG, COM Output

VLCBS1

VSS

Voltage follower for level voltage

−

UPD16680 Scheda tecnica(PDF) 13 Page - NEC