Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
Copyright © 2007
Rev. 1.0, 2007-10-30
WWW.Microsemi .COM
PanelMatch™
"
"
A
A
S
S
e
e
r
r
i
i
e
e
s
s
"
" LXMG1617A-05-2x
5V 2.2W CCFL Programmable Inverter Module
TM
®
TYPICAL APPLICATION
LXMG1617A-05-2x
5V
SET
2
GND
V
HI
V
LO
BRITE
V
IN
SLEEP
SET
1
0V to
2.0V
DAC or
Pot
CCFL
TUBE
NC
NC
500k
806
Optional
Resistor
to adjust
minimum
dimming
level
Figure 1 – Brightness Control
(Output current set to maximum)
P.W.
10µs to 500µS
BRITE
LXMG1617A-05-2x
0 < P.W. < 100% of period
PWM Signal
from System
Figure 1A – PWM Brightness Control
LXMG1617A-05-2x
SET
2
GND
V
HI
V
LO
SLEEP
SET
1
CCFL
TUBE
BRITE
5V
V
IN
L L 3.5mA
RMS
L H 4.0mA
RMS
H L 4.5mA
RMS
H H 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 500k manual pot. The
inverter contains an internal 215k pull-up to 3V to bias the
pot, it may be necessary to add a small value resistor in
series with the ground side of the POT to set the lower
threshold voltage above the absolute minimum dim level
capability, especially when both SET pins are programmed
low. 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 manufacturers. Generally the best
lamp lifetime correlates with driving the CCFL at the
manufacture’s 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 an 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 user’s 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 the
inverter will attempt to strike the lamp up to about one
second, after which (without success) the inverter will
shutdown, in this mode the inverter will draw about 8mA
from VIN. In order to restart the inverter it is necessary to
toggle the sleep input or cycle the V
IN
input supply.
A
A
P
P
P
P
L
L
I
I
C
C
A
A
T
T
I
I
O
O
N
N
