pca8576c NXP Semiconductors, pca8576c Datasheet - Page 14

• Manufacturer Part Number: pca8576c
• Description: Universal Lcd Driver For Low Multiplex Rates
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA8576C
Product data sheet
7.5.1 Internal clock
7.5.2 External clock
7.5 Oscillator
7.6 Timing
The internal logic and the LCD drive signals of the PCA8576C are timed by the frequency
f
f
The clock frequency (f
for data reception from the I
rate of 100 kHz, f
The internal oscillator is enabled by connecting pin OSC to pin V
output from pin CLK is the clock signal for any cascaded PCA8576C in the system.
Connecting pin OSC to V
external clock input.
Remark: A clock signal must always be supplied to the device. Removing the clock,
freezes the LCD in a DC state, which is not suitable for the liquid crystal.
The timing of the PCA8576C sequences 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 the PCA8576Cs in the system. The timing also generates the LCD
frame frequency which is derived as an integer division of the clock frequency (see
Table
internal clock is used or by the frequency applied to the pin CLK when an external clock is
used.
Table 6.
[1]
[2]
[3]
The ratio between the clock frequency and the LCD frame frequency depends on the
power mode in which the device is operating. In the power-saving mode the reduction
ratio is six times smaller; this allows the clock frequency to be reduced by a factor of six.
The reduced clock frequency results in a significant reduction in power consumption.
PCA8576C mode
Normal-power mode
Power-saving mode
clk
clk(ext)
, which equals either the built-in oscillator frequency f
The possible values for f
For f
For f
6). The frame frequency is set by the mode-set command (see
.
clk
clk
= 200 kHz.
= 31 kHz.
LCD frame frequencies
All information provided in this document is subject to legal disclaimers.
clk
should be chosen to be above 125 kHz.
clk
clk
) determines the LCD frame frequency (f
Rev. 1 — 22 July 2010
DD
see
2
enables an external clock source. Pin CLK then becomes the
C-bus. To allow I
Frame frequency
f
f
Table
fr
fr
=
=
[1]
------------ -
2880
--------- -
480
16.
f
f
clk
clk
Universal LCD driver for low multiplex rates
2
C-bus transmissions at their maximum data
osc
Nominal frame frequency (Hz)
69
65
or the external clock frequency
[2]
[3]
fr
SS
) and the maximum rate
PCA8576C
. In this case, the
Table
© NXP B.V. 2010. All rights reserved.
9) when an
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