PCA85133 NXP [NXP Semiconductors], PCA85133 Datasheet - Page 6

• Manufacturer Part Number: PCA85133
• Description: Universal LCD driver for low multiplex rates
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCA85133_1
Product data sheet
7.1 Power-on reset
7.2 LCD bias generator
7.3 LCD voltage selector
At power-on the PCA85133 resets to the following starting conditions:
Remark: Do not transfer data on the I
reset action to complete.
Fractional LCD biasing voltages are obtained from an internal voltage divider of three
series resistors between V
1
The LCD voltage selector coordinates the multiplexing of the LCD in accordance with the
selected LCD drive configuration. The operation of the voltage selector is controlled by the
mode-set command (see
configurations that apply to the preferred modes of operation, together with the biasing
characteristics as functions of V
Table
Table 5.
A practical value for V
threshold voltage (V
the static drive mode a suitable choice is V
Multiplex drive modes of 1:3 and 1:4 with
hence the contrast ratios are smaller.
LCD drive
mode
static
1:2 multiplex 2
1:2 multiplex 2
1:3 multiplex 3
1:4 multiplex 4
2
•
•
•
•
•
•
•
bias voltage level for the 1:2 multiplex configuration is selected.
All backplane and segment outputs are set to V
The selected drive mode is 1:4 multiplex with
Blinking is switched off
Input and output bank selectors are reset
The I
The data pointer and the subaddress counter are cleared (set to logic 0)
The display is disabled
5.
2
C-bus interface is initialized
Biasing characteristics
Number of:
Backplanes Levels
1
th
), typically when the LCD exhibits approximately 10 % contrast. In
LCD
Rev. 1 — 23 October 2009
Table
is determined by equating V
LCD
2
3
4
4
4
and V
LCD
10) from the command decoder. The biasing
LCD bias
configuration
static
1
1
1
1
and the resulting discrimination ratios (D), are given in
2
3
3
3
SS
2
C-bus for at least 1 ms after a power-on to allow the
. The center resistor is bypassed by switch if the
1
Universal LCD driver for low multiplex rates
LCD
2
bias are possible but the discrimination and
> 3V
1
3
LCD
th
V
--------------------------
0
0.354
0.333
0.333
0.333
bias
.
off RMS
V
off(RMS)
LCD
with a defined LCD
1
0.791
0.745
0.638
0.577
V
------------------------ - D
on RMS
V
LCD
PCA85133
© NXP B.V. 2009. All rights reserved.
2.236
2.236
1.915
1.732
=
--------------------------
V
V
off RMS
on RMS
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