pcf8534 NXP Semiconductors, pcf8534 Datasheet - Page 8

• Manufacturer Part Number: pcf8534
• Description: Universal Driver Multiplex Rates
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Table 5.
PCF8534_0
Preliminary datasheet
LCD drive
mode
static
1:2
1:2
1:3
1:4
Preferred LCD drive modes: summary of characteristics
Number of:
Backplanes
1
2
2
3
4
A practical value for V
voltage (V
drive mode a suitable choice is V
Multiplex drive ratios of 1:3 and 1:4 with
hence the contrast ratios are smaller e.g.:
The advantage of these modes is a reduction of the LCD full-scale voltage V
These compare with V
•
•
3
1:3 multiplex (
1:4 multiplex (
=
1.732 for 1:3 multiplex or
Levels
2
3
4
4
4
TH
), typically when the LCD exhibits approximately 10% contrast. In the static
1
1
⁄
⁄
2
2
Rev. 00.05 — 20 February 2007
bias):
bias):
OP
OP
is determined by equating V
LCD bias
configuration
static
1
1
1
1
= 3 x V
⁄
⁄
⁄
⁄
2
3
3
3
V
V
OP
OP
⎛
⎝
--------- -
=
=
OFF(rms)
OP
3
21
(
-------------------- -
> 3V
6
4
=
×
×
1.528
3
V
1
when
TH
0
0.354
0.333
0.333
0.333
V
---------------------- -
⁄
OFF rms
2
3
OFF ms
Universal LCD driver for low multiplex rates
.
bias are possible but the discrimination and
)
V
⎞ for 1:4 multiplex
⎠
OP
(
(
=
1
⁄
3
)
2.309V
)
bias is used. Note: V
=
OFF(rms)
2.449V
OFF rms
1
0.791
0.745
0.638
0.577
V
------------------- -
ON ms
(
V
OFF rms
with a defined LCD threshold
OP
(
)
(
)
)
OP
PCF8534
© NXP B.V. 2007. All rights reserved.
= V
∞
2.236
2.236
1.915
1.732
D
OP
=
LCD
---------------------- -
V
V
as follows:
OFF ms
.
ON ms
(
(
8 of 40
)
)