LCD principle

AN2687

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Doc ID 14296 Rev 1

The applied LCD voltage must also alternate to give a zero DC value to prevent the

electrolytic process and so, ensure a long LCD lifetime.

The higher the multiplexing rates, the lower the contrast. The signal period also has to be

short enough to avoid visible flickering on the display.

Figure 2.

Equivalent electrical schematic of an LCD segment

Note:

The DC value should never be more than 100 mV (refer to the LCD manufacturer’s

datasheet), otherwise the LCD lifetime may be shortened. The frequency range is 30 Hz to

200 Hz typically. If a lower frequency is used, the LCD flickers, if a larger frequency is used,

power consumption increases.

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