Microsemi

Integrated Products

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 5

Copyright

© 2002

Rev. 1.0b, 2005-01-17

PanelMatch

™

LXM1618-12-4x

12V 4W CCFL Programmable Inverter Module

I N T E GRA T ED

PRODUCT S

TY PI CAL APPLI CATI O N

LXM1618-12-4x

12V

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)

P.W .

10µs to 125µS

BRITE

LXM1618-12-4x

~26% < P.W. < 100% of

period

PW M Signal

from System

Figure 1A

– PWM Brightness Control

LXM1618-12-4x

SET

2

GND

V

HI

V

LO

SLEEP

SET

1

CCFL

TUBE

BRITE

12V

V

IN1

L

L

L

H

H

L

H

H

L=GND; H=Open

Figure 2

– Max Output Current

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

lamp current regulation. If both lamp wires have heavy

This wire is typically white.

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.

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

supply