P
RODUCTION
D
ATASHEET
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
Copyright
2002
Rev. 1.0a, 2006-11-13
W
M
.
C
PanelMatch
LXMG1618-03-2x
3.3V 2.2W CCFL Programmable Inverter Module
TM
T Y P I C A L A P P L I C A T I O N
LXMG1618-03-2x
3.3V
SET
2
GND
V
HI
V
LO
BRITE
V
IN1
SLEEP
SET
1
0.65V
to
2.0V
2.7K
20K
DAC or
Pot
CCFL
TUBE
NC
NC
Figure 1
– Brightness Control
(Output current set to maximum)
PWM Signal
from System
P.W.
10μs to 125μS
~26 < P.W. < 100%
of period
Figure 1A
– PWM Brightness Control
BRITE
LXMG1618-03-2x
LXMG1618-03-2x
SET
2
GND
V
HI
V
LO
SLEEP
SET
1
CCFL
TUBE
BRITE
3.3V
V
IN1
L
L
H
H
L
H
L
H
3.5mA
RMS
4.0mA
RMS
4.5mA
RMS
5.0mA
RMS
L=GND; H= Open
Figure 2
– Max Output Current
(SET
1
and SET
2
Inputs)
The brightness control may be a voltage output DAC or
other voltage source, a digital pot or 20K manual pot. The
inverter contains an internal 10K pull-up to 3V to bias the
pot add a 2.7K resistor to set the lower threshold voltage.
A 3.3V Logic Level PWM signal from a micro-controller
may also be used as shown in Figure 1A.
If you need to turn the inverter ON/OFF remotely, connect
to TTL logic signal to the
SLEEP
input.
Connect V
HI
to high voltage wire from the lamp. Connect
V
LO
to the low voltage wire (wire with thinner insulation).
Never connect V
LO
to circuit ground as this will defeat
lamp current regulation. If both lamp wires have heavy
high voltage insulation, connect the longest wire to V
LO
.
This wire is typically white.
Use the SET
1
and SET
2
(see Figure 2) inputs to select
the desired maximum output current. Using these two pins
in combination allows the inverter to match a wide variety
of panels from different manufactures. Generally the best
lamp lifetime and efficiency correlates with driving the
CCFL at the manufactures nominal current setting.
However the SET
1
and SET
2
inputs allow the user the
flexibility to adjust the current to the maximum allowable
output current to increase panel brightness at the expense of
some reduced lamp life.
Although the SET pins are designed such that just
leaving them open or grounding them is all that is needed to
set the output current, they can also be actively set. Using a
open collector or open drain logic signal will allow you to
reduce the lamp current for situations where greater dim
range is required, as an example in nighttime situations. In
conjunction with a light sensor or other timer the panel
could be set to higher brightness (maximum output current)
for daytime illumination and lower brightness (minimum or
typical output current) at nighttime. Since the dim ratio is a
factor the peak output current, using this technique the
effective dim ratio can be increased. Conversely the SET
inputs could be used to overdrive the lamp temporarily to
facilitate faster lamp warm up at initial lamp turn on. Of
course any possible degradation on lamp life from such
practices is the users responsibility as not all lamps are
designed to be overdriven.
The inverter has a built in fault timeout function. If
the output is open (lamp disconnected or broken) or shorted
the inverter will attempt to strike the lamp for several
seconds. After about 2 seconds without success the inverter
will shutdown. In order to restart the inverter it is
necessary to toggle the sleep input or cycle the V
IN1
input
supply.
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