LCD displays are available in two temperature ranges, Standard and Extended. A Standard temperature range display is intended for use indoors and an Extended range display is for use outdoors and in rugged environments.
STANDARD TEMPERATURE
EXTENDED TEMPERATURE
OPERATING
STORAGE
OPERATING
STORAGE
0°C - 50°C
-20°C - 70°C
-20°C - 70°C
-30°C - 85°C
The contrast adjustment voltage is specified for a given temperature. This is done because the LCD fluid is sensitive to temperature. In a Standard temperature range module the variation of contrast over the temperature range is small enough so that no temperature compensation is required. In the Extended temperature models however a temperature compensation circuit is often used to retain optimal contrast at the extremes of temperature. Figure #1 is the characteristic curve for an Extended temperature display and Figure #2 is a suggested circuit for temperature compensation with a character module.
Figure #1
Figure #2
All of our Standard temperature character modules will operate from a single 5-volt power source. Extended temperature models generally require a negative 5-volt power source to operate the contrast control. Figure #3 illustrates the single and dual power supply circuits generally used.
