PCF8545ATT datasheet(9/72 Pages) NXP

9 / 72 page

PCF8545

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Product data sheet

Rev. 1 — 13 November 2013

9 of 72

NXP Semiconductors

PCF8545

Universal LCD driver for multiplex rates up to 1:8

8.1.3.2

Line inversion (driving scheme A) and frame inversion (driving scheme B)

The DC offset of the voltage across the LCD is compensated over a certain period:

line-wise in line inversion mode (driving scheme A) or frame-wise in frame inversion mode

(driving scheme B). With the INV bit (see Table 8), the compensation mode can be

switched.

In frame inversion mode, the DC value is compensated across two frames and not within

one frame. Changing the inversion mode to frame inversion reduces the power

consumption; therefore it is useful when power consumption is a key point in the

application.

Frame inversion may not be suitable for all applications. The RMS voltage across a

segment is better defined; however, since the switching frequency is reduced, there is

possibility for flicker to occur.

The waveforms of Figure 14 on page 24 to Figure 17 on page 27 are showing line

inversion mode. Figure 18 on page 28 shows an example of frame inversion.

8.1.3.3

Power-down mode

The power-down bit (PD) allows the PCF8545 to be put in a minimum power

configuration. To avoid display artifacts, enter power-down only after the display has been

switched off by setting bit E to logic 0. During power-down, the internal oscillator is

switched off.

Fig 5.

Effect of backplane swapping

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