Landmark Technology
LM130A-12C318 P.4
Landmark Technology 172 Component Drive, San Jose, CA 95131 (408) 434-9302 Fax: (408) 434-0954 08/2002
Backlight Lamp Connections
The very high brightness (VHB) backlight in the LM130A-12C318 module utilizes a total of 8 cold cathode
fluorescent lamps to achieve the required luminance. The lamps are electrically connected in a parallel circuit:
that is, they are connected at one side
to a common lead.
The lamps are oriented in the
horizontal direction with the #1 lamp
at the top side of the LCD. The lead
wires connecting the lamps are
terminated with two 11-pin Molex
connectors. The figure on the left
shows
the
connector
pinout
assignments. Customized lamp wire
terminations with other connectors
are available on request.
It is recommended that an inverter with a 1200 to 1300
Vrms starting voltage be used to run the VHB backlight on
the LM130A-12C318 module. At the maximum LCD
screen luminance, the lamp voltage and current are listed
below:
Operating Voltage
470
Vrms
Lamp Current
5.7
mArms
At this driving condition, the backlight delivers about
1,350 Cd/m
2 LCD screen luminance with a power
consumption of about 21 Watts. Since most inverters have
an efficiency level between 70 - 80%, the total DC power
input to the inverter is about 28 to 26.3 Watts. When the
backlight is dimmed down, the power consumption
decreases.
It is quite difficult to measure the lamp current
accurately. As a result, if you intend to run the
LM130A-12C318 VHB backlight with your own
inverter, please measure the screen brightness
instead. Then use the brightness data to determine the
correct driving condition. To do so, turn on the
inverter to operate the backlight, but do not turn on
the LCD. Make sure that the room temperature is
about 25 °C and run the backlight for at least 30
minutes before measuring the screen brightness. If the
measured screen brightness exceeds the specified
value by a significant margin, for example, more than
15%, the lamps are over-driven. Over-driving the
lamps can cause a significant reduction in backlight
life.
Backlight Lamp Driving Specifications