PCF8545ATT datasheet(8/54 Pages) NXP

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PCA8576F

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Product data sheet

Rev. 3 — 3 December 2014

8 of 54

NXP Semiconductors

PCA8576F

Automotive 40 × 4 LCD driver

Remark: A clock signal must always be supplied to the device; removing the clock may

freeze the LCD in a DC state, which is not suitable for the liquid crystal.

7.2.3 Timing and frame frequency

The PCA8576F timing controls 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 correct timing relationship between each PCA8576F in the system is

maintained by the synchronization signal at pin SYNC. The timing also generates the LCD

frame signal whose frequency is derived from the clock frequency. The frame signal

frequency is a fixed division of the clock frequency from either the internal or an external

clock:

7.2.4 Blinking

The display blinking capabilities of the PCA8576F are very versatile. The whole display

can blink at frequencies selected by the blink-select command (see Table 11). The blink

frequencies are derived from the clock frequency. The ratio between the clock and blink

frequencies depends on the blink mode selected (see Table 11).

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

applies to the static and 1:2 multiplex 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 blink frequency. This mode can

also be specified by the blink-select command.

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

LCD segments/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 7).

[1]

Blink modes 1, 2 and 3 and the nominal blink frequencies correspond to an oscillator frequency (fclk) of

4800 Hz (see Section 13).

clk

-------

Table 12.

Blinking frequencies

Blink mode

Normal operating mode ratio

Nominal blink frequency[1]

Unit

off

blinking off

16.2

23.1

31.6

clk

768

----------

clk

1536

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

clk

3072

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

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