PCA85133 NXP [NXP Semiconductors], PCA85133 Datasheet - Page 13

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

NXP Semiconductors
PCA85133_1
Product data sheet
7.5.1 Internal clock
7.5.2 External clock
7.5 Oscillator
7.6 Timing and frame frequency
7.7 Display register
The internal logic and the LCD drive signals of the PCA85133 are timed by a frequency
f
or equals an external clock frequency f
The internal oscillator is enabled by connecting pin OSC to V
from pin CLK provides the clock signal for any cascaded PCA85133 in the system. After
power-on, pin SDA must be HIGH to guarantee that the clock starts.
Connecting pin OSC to V
external clock input.
Remark: A clock signal must always be supplied to the device; removing the clock may
freeze the LCD in a DC state, which is not suitable for the liquid crystal.
The clock frequency f
follows:
The internal clock frequency f
frequencies are available: 82 Hz or 110 Hz (typical), see
Table 6.
The timing of the PCA85133 organizes the internal data flow of the device. This includes
the transfer of display data from the display RAM to the display segment outputs. In
cascaded applications, the synchronization signal (SYNC) maintains the correct timing
relationship between all the PCA85133 in the system.
The display register holds the display data while the corresponding multiplex signals are
generated. There is a one-to-one relationship between the data in the display register, the
LCD segment outputs and one column of the display RAM.
f
Pin FF tied to
V
V
clk
f
f
clk
clk
fr
DD
SS
which either is derived from the built-in oscillator frequency f
=
=
=
---------
f
24
clk
--------- -
f
f
64
osc
clk ext
LCD frame frequencies
clk
Rev. 1 — 23 October 2009
determines the LCD frame frequency f
DD
enables an external clock source. Pin CLK then becomes the
Typical clock frequency (Hz)
1970
2640
clk
can be selected using pin FF. As a result 2 frame
clk(ext)
Universal LCD driver for low multiplex rates
:
Table
LCD frame frequency (Hz)
82
110
SS
fr
6.
. In this case the output
osc
and is calculated as
:
PCA85133
© NXP B.V. 2009. All rights reserved.
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