LXMG1643-12-64 Datasheet, PDF (5/6 Pages) Microsemi Corporation – 12V Quad 6W CCFL Programmable Inverter Module

PanelMatch™
LXMG1643-12-64
TM
®
12V Quad 6W CCFL Programmable Inverter Module
PRODUCTION DATASHEET
TYPICAL APPLICATION
DAC or
Pot
0.45V _20K
to 2.0V
1.8K
12V
BRITE
V_IN1
V_Hx
V_Hx
LXMG1643-12-64
SLEEP
SET₁ SET₂
NC
NC
V_LOx
V_LOx
GND
One of two
Figure 1 – Brightness Control
(Output current set to maximum)
PWM Signal
from System
BRITE
P.W.
LXMG1643-12-64
10µs to 125µS
0 < P.W. < 100% of period
Figure 1A – PWM Brightness Control
BRITE
12V
V_IN1
LXM G1643-12-64
SLEEP
SET ₁ SET ₂
GND
One of two
L
L
5.0mA_RMS
L
H
6.0mA_RMS
H
L
7.0mA_RMS
H
H
8.0mA_RMS
L=GND; H=Open
Figure 2 – Max Output Current
(SET₁ and SET₂ Inputs)
ƒ 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.
ƒ If you need to turn the inverter ON / OFF remotely,
connect to TTL logic signal to the SLEEP input.
ƒ 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.
ƒ Use the SET₁ and SET₂ (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 SET₁
and SET₂ 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.
ƒ 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 users
responsibility since not all lamps are designed to be
overdriven.
ƒ The inverter has a built in fault timeout function. If the
output return is open (lamp disconnected or broken) or
shorted the inverter will attempt to strike the lamp for
several seconds. After about a second without success the
inverter will shutdown. In order to restart the inverter it is
necessary to toggle the sleep input or cycle the VIN1 input
supply. In the timeout shutdown mode input drain current
will be about 8mA.
Copyright © 2005
Rev. 1.1, 2006-11-16
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
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