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Temperature Considerations
Thermal Shutdown
A thermal sensor referenced to the center of the backlight/inverter ECA prevents the
inverter from starting at an ambient temperature of –30 C or below, and will shut off the
backlight at an ambient temperature of approximately +90 C and above.
Luminance Variation Due to Ambient Temperature
Although the inverter features regulated lamp current drive, luminance will vary across
the temperature range due to the characteristics of the CCFL tubes. Lamp luminance
decreases at low temperatures as the mercury condenses out of the gas and it decreases
again at high temperatures as the tube phosphors become less efficient. The
LC640.480.33-AC has been designed to provide peak luminance at normal room
temperatures.
Backlight power consumption decreases as temperatures climb as the working voltage of
the CCFL tubes decreases. The graph in Figure 13 indicates typical performance across
temperature.
Figure 13. Luminance vs. Temperature.
100
90
80
70
60
50
40
30
20
10
22
LC640.480.33-AC Operations Manual (OM600-01)
Luminance vs. Temperature
0
-20 -10
0
10
20
30
40
50
60
70
ta, C
30.0
25.0
20.0
15.0
10.0
5.0
0.0
80
Lum, %
PH, W
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