Microsemi

Analog Mixed Signal Group

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

Page 5

Copyright

© 2007

Rev. 1.1, 2010-02-26

PanelMatch™

LXMG1617A-05-6x

5V 6W CCFL Programmable Inverter Module

TM

®

TYPICAL APPLICA T ION

LXMG1617A-05-6x

5V

GND

BRITE

SLEEP

0V to

2.0V 500k

DAC or

Pot

CCFL

TUBE

NC

NC

Figure 1

– Brightness Control

(output current set to maximum)

P.W.

10µs to 500µS

BRITE

LXMG1617A-05-6x

0 < P.W. < 100% of period

PWM Signal

from System

Figure 1A

– PWM Brightness Control

LXMG1617A-05-6x

GND

SLEEP

CCFL

TUBE

BRITE

5V

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, if

desired; add a resistor to set the lower threshold voltage above

the absolute minimum dim level capability. A PWM logic

level signal (figure 1A) may be used up to 5V; however the

inverter will reach maximum current at less than 100% duty

cycle. This can be calculated as approximately 2V divided by

the logic high voltage level; with 3.3V logic level this

corresponds to about 60% duty cycle for maximum lamp

current.

If you need to turn the inverter ON/OFF remotely, connect to

TTL logic signal to the

SLEEP input.

to the low voltage wire (wire with thinner insulation). Never

regulation.

If both lamp wires have heavy high voltage

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 manufacturers. Generally the best lamp

lifetime correlates with driving the CCFL at the manufacture’s

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

restart the inverter it is necessary to toggle the sleep input or