Planar LC640.480.33-AC manual Temperature Considerations, Thermal Shutdown

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.

				Luminance vs. Temperature
	100										30.0
	90										25.0	W
	80
Luminance,%											5.0	BacklightPower,
	20
	70										20.0
	60
	50										15.0
	40										10.0
	30
	10
	0										0.0
	-20	-10	0	10	20	30	40	50	60	70	80	Lum, %

ta, C PH, W

22 LC640.480.33-AC Operations Manual (OM600-01)