Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
Copyright © 2003
Rev. 1.1, 2006-11-15
WWW.Microsemi .COM
PanelMatch
LXMG1623-12-44
12V Dual 4W CCFL Programmable Inverter Module
TM
®
TYPICAL APPLICATION
LXMG1623-12-44
12V
SET
2
GND
V
HI
V
LO
BRITE
V
IN1
SLEEP
SET
1
0.45V
to
2.0V
1.8K
20K
DAC or
Pot
CCFL
TUBE
NC
NC
ONE OF
TWO
Figure 1 – Brightness Control
(Output current set to maximum)
P.W.
2.5µs to 125µS
BRITE
LXMG1623-12-44
0 < P.W. < 100% of period
PWM Signal
from System
Figure 1A – PWM Brightness Control
LXMG1623-12-44
SET
2
GND
V
HI
V
LO
SLEEP
SET
1
CCFL
TUBE
BRITE
12V
V
IN1
ONE OF
TWO
L L 5.2mA
RMS
L H 5.7mA
RMS
H L 6.2mA
RMS
H H 6.7mA
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 1.8K 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 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 of both the burst duty cycle and the
peak output current, using this technique the effective dim
ratio can be increased greater than the burst duty cycle
alone. 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 since 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 to
ground the inverter will attempt to strike the lamp for
several seconds. After about 3 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
A
A
P
P
P
P
L
L
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C
C
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