Philips Semiconductors
LCD column driver for dot matrix graphic
displays
Product specification
PCF8579
1997 Apr 01
ROW 1
R1 (t)
VDD
V2
V3
V4
V5
V LCD
ROW 2
R2 (t)
VDD
V2
V3
V4
V5
V LCD
COL 1
C1 (t)
VDD
V2
V3
V4
V5
V LCD
COL 2
C2 (t)
VDD
V2
V3
V4
V5
V LCD
V op
V state 1 (t)
0.261 Vop
0V
0.261 Vop
T frame
V op
V state 2 (t)
V op
0.478 Vop
0.261 Vop
0V
0.261 Vop
0.478 Vop
V op
Vstate 1 (t) = C1(t) R1(t):
Von(rms) =
Vop
1
8
8
(
8
8
1
1)
=
0.430
Vstate 2 (t) = C2(t) R2(t):
Voff(rms) =
Vop
2(
8
(
8
8
1)
1) 2
=
0.297
state 1 (OFF)
state 2 (ON)
dot matrix
1:8 multiplex rate
MSA840
general relationship (n = multiplex rate)
Von(rms) =
Vop
1
n1
n n ( n 1)
Voff(rms) =
Vop
2( n 1)
n ( n 1)2
Fig.6 LCD drive mode waveforms for 1 : 8 multiplex rate.
10