2004 Dec 22

11

Philips Semiconductors

Product specification

Universal LCD driver for low

multiplex rates

PCF8576D

Table 2

Discrimination ratios

6.4

LCD drive mode waveforms

6.4.1

The static LCD drive mode is used when a single backplane is provided in the LCD. The backplane (BPn) and segment

LCD DRIVE MODE

NUMBER OF

LCD BIAS

CONFIGURATION

BACKPLANES

LEVELS

static

1

2

static

0

1

∞

1 : 2 multiplex

2

3

1

0.354

0.791

2.236

1 : 2 multiplex

2

4

1

0.333

0.745

2.236

1 : 3 multiplex

3

4

1

0.333

0.638

1.915

1 : 4 multiplex

4

4

1

0.333

0.577

1.732

V

off(rms)

V

lcd

---------------------

V

on(rms)

V

lcd

---------------------

D

V

on(rms)

V

off(rms)

---------------------

=

handbook, full pagewidth

MGL745

VSS

VLCD

VSS

VLCD

VSS

VLCD

VLCD

−VLCD

−VLCD

VLCD

state 1

0 V

BP0

Sn

Sn + 1

state 2

0 V

(a) Waveforms at driver.

(b) Resultant waveforms

at LCD segment.

LCD segments

state 1

(on)

state 2

(off)

Tframe

Fig.6 Static drive mode waveforms.

V

on(rms)

V

LCD

=

V

()

V

S

n1

+

t

()

V

()

–

=

V

off(rms)

0V

=