Microsemi

Integrated Products

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

Page 5

Copyright

© 2003

Rev. 1.1a, 2005-01-17

PanelMatch

™

LXM1626-12-64

12V Dual 6W CCFL Programmable Inverter Module

TM

®

TY PI CAL APPLI CATI O N

LXM1626-12-64

12V

SET

2

GND

V

HI

V

LO

BRITE

V

IN1

SLEEP

SET

1

500K

DAC or

Pot

CCFL

TUBE

NC

NC

ONE OF

TWO

Figure 1

– Brightness Control

(Output current set to maximum)

P.W.

10µs to 20µS

BRITE

LXM1626-12-64

0 < P.W. < 100% of period

PWM Signal

from System

Figure 1A

– PWM Brightness Control

LXM1626-12-64

SET

2

GND

V

HI

V

LO

SLEEP

SET

1

CCFL

TUBE

BRITE

12V

V

IN1

ONE OF

TWO

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 500K manual pot. The

inverter contains an internal 215K pull-up to 3V to bias the

pot.

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.

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

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 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 to

ground the inverter will attempt to strike the lamp for

number of cycles. After about 800 milliseconds without

success the inverter will shutdown. In order to restart the

inverter it is necessary to toggle the SLEEP input or cycle