PCF8533U PHILIPS [NXP Semiconductors], PCF8533U Datasheet - Page 7

• Manufacturer Part Number: PCF8533U
• Description: Universal LCD driver for low multiplex rates
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
6.1
At Power-on the PCF8533 resets to a starting condition as
follows:
1. All backplane outputs are set to V
2. All segment outputs are set to V
3. The drive mode ‘1 : 4 multiplex with
4. Blinking is switched off.
5. Input and output bank selectors are reset (as defined
6. The I
7. The data pointer and the subaddress counter are
8. Display disabled.
Data transfers on the I
following Power-on to allow completion of the reset action.
6.2
Fractional LCD biasing voltages are obtained from an
internal voltage divider of the three series resistors
connected between V
be switched out of the circuit to provide a
level for the 1 : 2 multiplex configuration.
6.3
The LCD voltage selector co-ordinates the multiplexing of
the LCD in accordance with the selected LCD drive
configuration. The operation of the voltage selector is
controlled by MODE SET commands from the command
decoder.
Table 2 Preferred LCD drive modes: summary of characteristics
1999 Jul 30
static
1 : 2
1 : 2
1 : 3
1 : 4
LCD DRIVE MODE
Universal LCD driver for low multiplex rates
in Table 5).
cleared.
Power-on reset
LCD bias generator
LCD voltage selector
2
C-bus interface is initialized.
LCD
2
1
2
2
3
4
C-bus should be avoided for 1 ms
BACKPLANES LEVELS
and V
NUMBER OF
SS
. The centre resistor can
LCD
LCD
1
.
3
2
3
4
4
4
.
bias’ is selected.
1
2
bias voltage
static
1
1
1
1
CONFIGURATION
2
3
3
3
LCD BIAS
7
The biasing configurations that apply to the preferred
modes of operation, together with the biasing
characteristics as functions of V
discrimination ratios (D), are given in Table 2.
A practical value for V
with a defined LCD threshold voltage (V
the LCD exhibits approximately 10% contrast. In the static
drive mode a suitable choice is V
Multiplex drive ratios of 1 : 3 and 1 : 4 with
possible but the discrimination and hence the contrast
ratios are smaller (
The advantage of these modes is a reduction of the LCD
full-scale voltage V
These compare with V
Note: V
----------
3
21
1 : 3 multiplex (
1 : 4 multiplex (
V
V
OP
OP
= 1.528 for 1 : 4 multiplex).
OP
=
=
= V
6 V
--------------------- -
4
0
0.354
0.333
0.333
0.333
LCD
V
------------------ -
3
off(rms)
V
off(rms)
.
OP
1
1
3
OP
2
2
bias):
bias):
3
OP
=
as follows:
OP
= 1.732 for 1 : 3 multiplex or
2.309V
=
is determined by equating V
= 3V
2.449V
1
0.791
0.745
0.638
0.577
V
------------------ -
off(rms)
on(rms)
V
off(rms)
OP
OP
OP
off(rms)
and the resulting
> 3V
when
Product specification
th
PCF8533
th
), typically when
.
1
1
3
2.236
2.236
1.915
1.732
D
2
bias is used.
bias are
=
V
------------------ -
V
on(rms)
off(rms)
off(rms)