2004 Dec 22

18

Philips Semiconductors

Product specification

Universal LCD driver for low

multiplex rates

PCF8576D

6.14

Input bank selector

The input bank selector loads display data into the display

RAM in accordance with the selected LCD drive

configuration. The BANK SELECT command can be used

to load display data in bit 2 in static drive mode or in

bits 2 and 3 in 1 : 2 mode. The input bank selector

functions are independent of the output bank selector.

6.15

Blinker

The PCF8576D has a very versatile display blinking

capability. The whole display can blink at a frequency

selected by the BLINK command. Each blink frequency is

a multiple integer value of the clock frequency; the ratio

between the clock frequency and blink frequency depends

on the blink mode selected, as shown in Table 3.

An additional feature allows an arbitrary selection of LCD

segments to be blinked in the static and 1 : 2 drive modes.

This is implemented without any communication

overheads by the output bank selector which alternates

the displayed data between the data in the display RAM

bank and the data in an alternative RAM bank at the blink

frequency. This mode can also be implemented by the

BLINK command.

In the 1 : 3 and 1 : 4 drive modes, where no alternative

RAM bank is available, groups of LCD segments can be

blinked by selectively changing the display RAM data at

fixed time intervals.

The entire display can be blinked at a frequency other than

the nominal blink frequency by sequentially resetting and

setting the display enable bit E at the required rate using

the MODE SET command.

Table 3

Blinking frequencies

Note

1. Blink modes 0.5, 1 and 2 Hz, and nominal blink frequencies 0.5, 1 and 2 Hz correspond to an oscillator frequency

BLINK MODE

NORMAL OPERATING MODE

RATIO

NOMINAL BLINK 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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