1998 May 04

8

Philips Semiconductors

Product specification

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

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.

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

−Vop

Vop

−Vop

Tframe

Sn

Sn + 1