
1998 May 04
8
Philips Semiconductors
Product specication
Universal LCD driver for low multiplex
rates
PCF8566
6.4
LCD drive mode waveforms
The static LCD drive mode is used when a single backplane is provided in the LCD. Backplane and segment drive
waveforms for this mode are shown in Fig.4.
When two backplanes are provided in the LCD the 1 : 2 multiplex drive mode applies. The PCF8566 allows use of
1
2 or 13 bias in this mode as shown in Figs 5 and 6.
The backplane and segment drive waveforms for the 1 : 3 multiplex drive mode (three LCD backplanes) and for the 1 : 4
multiplex drive mode (four LCD backplanes) are shown in Figs 7 and 8 respectively.
Fig.4 Static drive mode waveforms: Vop =VDD VLCD.
handbook, full pagewidth
MGG392
state 1
At any instant (t):
Vstate 1(t) = VSn(t) VBP0(t)
Von(rms) = Vop
Vstate 2(t) = VSn + 1(t) VBP0(t)
Voff(rms) = 0 V
0
BP0
state 2
0
(a) waveforms at driver
(b) resultant waveforms
at LCD segment
LCD segments
state 1
(on)
state 2
(off)
VDD
VLCD
VDD
VLCD
VDD
VLCD
Vop
Tframe
Sn
Sn + 1