1999 Jul 30

16

Philips Semiconductors

Product specification

Universal LCD driver for low multiplex rates

PCF8533

the BANK SELECT command. The input bank selector

functions independently to the output bank selector.

6.15

Blinker

The display blinking capabilities of the PCF8533 are very

versatile. The whole display can be blinked at frequencies

selected by the BLINK command. The blinking frequencies

are integer multiples of the clock frequency. The ratios

between the clock and blinking frequencies depend on the

mode in which the device is operating, see Table 4.

An additional feature is for an arbitrary selection of LCD

segments to be blinked. This applies to the static and

1 : 2 LCD drive modes and can be implemented without

any communication overheads. By means of 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.

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 is to be blinked at a frequency other than the nominal blinking frequency, this can be effectively

performed by resetting and setting the display enable bit E at the required rate using the MODE SET command.

Table 4

Blinking frequencies

BLINKING MODE

NORMAL OPERATING MODE

RATIO

NOMINAL BLINKING FREQUENCY

Off

−

blinking off

2Hz

2Hz

1Hz

1Hz

0.5 Hz

0.5 Hz

f

CLK

768

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f

CLK

1536

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f

CLK

3072

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