pca8576d NXP Semiconductors, pca8576d Datasheet - Page 6

• Manufacturer Part Number: pca8576d
• Description: Automotive 40 X 4 Lcd Segment Driver For Low Multiplex Rates Up To 1 4
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA8576D
Product data sheet
7.2 LCD bias generator
7.3 LCD voltage selector
Data transfers on the I
reset action to complete.
Fractional LCD biasing voltages are obtained from an internal voltage divider consisting of
three impedances connected in series between V
bypassed to provide a
voltage can be temperature compensated externally using the supply to pin V
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.
Bias is calculated by
The RMS on-state voltage (V
V
LCD drive
mode
static
1:2 multiplex 2
1:2 multiplex 2
1:3 multiplex 3
1:4 multiplex 4
•
•
•
•
on RMS
a = 1 for
a = 2 for

Input and output bank selectors are reset
The I
The data pointer and the subaddress counter are cleared (set to logic 0)
Display is disabled
5.

2
=
C-bus interface is initialized
Discrimination ratios
1
1


V
2
3
LCD
Number of:
Backplanes Levels
1
bias
bias
All information provided in this document is subject to legal disclaimers.
----------------------------- -
n
a
2

th
+

------------ -
1
), typically when the LCD exhibits approximately 10 % contrast. In
1
LCD
2a
2
1
Automotive 40 x 4 LCD segment driver for low multiplex rates
C-bus must be avoided for 1 ms following power-on to allow the
1
+
+

2
Rev. 1 — 4 April 2011
a
+
a
bias voltage level for the 1:2 multiplex configuration. The LCD
Table
is determined by equating V

, where the values for a are
n
2
3
4
4
4
2
on(RMS)
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




) for the LCD is calculated with
2
3
3
3
1

LCD
2
bias are possible but the discrimination and
> 3V
LCD
th
0
0.354
0.333
0.333
0.333
V
------------------------ -
.
and V
off RMS
V
off(RMS)
LCD

SS

. The middle resistor can be
with a defined LCD
1
0.791
0.745
0.638
0.577
V
----------------------- -
on RMS
V

LCD
PCA8576D
Equation 1

© NXP B.V. 2011. All rights reserved.

2.236
2.236
1.915
1.732
D
=
LCD
------------------------ -
V
V
off RMS
on RMS
.


6 of 42

(1)
