PCF8534A datasheet(23/52 Pages) NXP

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PCF8534A

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Product data sheet

Rev. 6 — 25 July 2011

23 of 52

NXP Semiconductors

PCF8534A

Universal LCD driver for low multiplex rates

An additional feature is for an arbitrary selection of LCD segments to blink. This applies to

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

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

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

specified by the blink-select command.

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

LCD elements can blink by selectively changing the display RAM data at fixed time

intervals.

The entire display can blink at a frequency other than the nominal blink frequency. This

can be effectively performed by resetting and setting the display enable bit E at the

required rate using the mode-set command (see Table 11).

7.12 Command decoder

The command decoder identifies command bytes that arrive on the I2C-bus. The

commands available to the PCF8534A are defined in Table 10.

Table 9.

Blink frequencies

Blink mode

Operating mode ratio

Blink frequency with respect to fclk (typical)

Unit

fclk = 1536 Hz

off

blinking off

30.5

blink

clk

768

---------

blink

clk

1536

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

blink

clk

3072

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

Table 10.

Definition of commands

Command

Operation code

Reference

mode set

110

M[1:0]

Table 11

load data pointer

P[6:0]

Table 12

device select

A[2:0]

Table 13

bank select

Table 14

blink select

BF[1:0]

Table 15

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