PCF8576CUSLASH2 datasheet(22/56 Pages) NXP

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PCF8576C_9

Product data sheet

Rev. 09 — 9 July 2009

22 of 56

NXP Semiconductors

PCF8576C

Universal LCD driver for low multiplex rates

The PCF8576C includes a RAM bank switching feature in the static and 1:2 multiplex

drive modes. In the static drive mode, the bank select command may request the contents

of bit 2 to be selected for display instead of the contents of bit 0. In 1:2 multiplex drive

mode, the contents of bits 2 and 3 may be selected instead of bits 0 and 1. This enables

preparation of display information in an alternative bank and the ability to switch to it once

it has been assembled.

7.14.2 Input bank selector

The input bank selector (see Table 15) loads display data into the display RAM based on

the selected LCD drive conﬁguration. Using the bank select command, display data can

be loaded in bit 2 into static drive mode or in bits 2 and 3 into 1:2 multiplex drive mode.

The input bank selector functions independently of the output bank selector.

7.15 Blinker

The display blinking capabilities of the PCF8576C are very versatile. The whole display

can be blinked at frequencies selected by the blink command. The blinking frequencies

are integer fractions of the clock frequency; the ratios between the clock and blinking

frequencies depend on the mode in which the device is operating (see Table 7).

An additional feature is for an arbitrary selection of LCD segments to be blinked. This

applies to the static and 1:2 multiplex drive modes and can be implemented without any

communication overheads. Using the output bank selector, the displayed RAM banks are

exchanged with alternate RAM banks at the blinking frequency. This mode can also be

speciﬁed by the blink command (see Table 16).

In the 1:3 and 1:4 multiplex modes, where no alternate RAM bank is available, groups of

LCD segments can be blinked by selectively changing the display RAM data at ﬁxed time

intervals.

If the entire display needs to be blinked at a frequency other than the nominal blink

frequency, this can be done using the mode set command to set and reset the display

enable bit E at the required rate (see Table 9).

Table 7.

Blink frequencies

Blinking mode

Normal operating

mode ratio

Power saving mode

ratio

Blink frequency

off

blinking off

2 Hz

1 Hz

0.5 Hz

blink

clk

92160

----------------

blink

clk

15360

----------------

blink

clk

184320

--------------------

blink

clk

30720

----------------

blink

clk

368640

--------------------

blink

clk

61440

----------------

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