Microsemi

Integrated Products

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

Page 5

Copyright

© 2000

Rev. 1.1, 2006-09-05

LXMG1612-05-xx

5V Highly-Integrated, Digital Dimming CCFL Inverter Module

TM

®

HOW RANGEMAX WORKS (CONTINUED)

Highlights

Integrated brightness control circuit includes a DC voltage

to pulse width converter that minimizes system design

work and system noise susceptibility. This provides a

familiar and convenient interface while reducing the

potential for externally induced noise, which can cause

lamp flicker.

RangeMAX inverter modules are designed to operate with

the burst frequency synchronized to the video frame rate.

This

provides

operation

with

no

visible

display

disturbances caused by beat frequencies between the lamps

and video frame rates.

In this synchronous mode, the

inverter burst rate operates at twice the video refresh rate,

well beyond standard 50/60Hz video refresh rates where

the eye can perceive pulsing light.

In applications with no access to a vertical sync., an onboard

oscillator operates the inverter burst rate at about 250Hz. In

this non-synchronous mode, minor display disturbances can

be found under certain video conditions. This performance

may

be

acceptable

for

many

applications,

but

synchronization must be used when no disturbance can be

tolerated.

A single input will accommodate negative and positive

vertical sync pulses at any pulse width.

Separate feedback loops for lamp current and open circuit

voltage regulation insure reliable strike under all operating

conditions, automatic over-voltage prevention with broken

or failed lamps, and accurate lamp current regulation.

TY PICAL APPLICATION

LXMG1612-05-xx

5V

V

SYNC

V

SYNC

GND

V

HI

V

LO

BRITE

Figure 5 - Potentiometer Brightness Control

V

IN1

CCFL

TUBE

BRITE RTN

R

10k

SLEEP

0V

5V

DAC or

Pot

P.W.

2ms

BRITE

LXMG1612-05-xx

0 < P.W. < 100% of period

PWM Signal

from System

Figure 5A - PWM Brightness Control

The brightness control may be a voltage output DAC, digital

resistor or a simple 10k potentiometer.

If desired, an

additional series resistor with the 10k potentiometer can be

used to set a higher minimum brightness setting as shown in

Figure 5. A 2.5V to 5V Logic Level PWM signal from a

micro-controller may also be used as shown in Figure 5A.

If synchronization to the video frame rate is desired, connect

the vertical sync pulse from the system video controller to

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

to 2.5V to 5V logic signal to the SLEEP input.

current regulation.

If both lamp wires have heavy high

wire is typically white.

LXMG1612-05-XX OUTPUT CURRENT ADJUST

The LXMG1612-05 output current can be adjusted by changing the

value of two resistors on the PCB. The following table shows the

approximate new output current values:

Output Current

R12

R16

7.0mA

2.00K 1%

Not Used

6.0mA

2.61K 1%

Not Used

5.8mA

2.74K 1%

Not Used

5.0mA

2.74K 1%

499K 1%

4.0mA

2.74K 1%

178K 1%

3.0mA

2.74K 1%

78.7K 1%

C2

U1

C9

R7

C11

R14

R15

C15

C12

R11

C14

C13

R10

C16

C10

R13

R3

R4

C3

C4

R2

C5

C6

C8

R5

R6

C21

R38

R39

R41

R20

C7

R21

R34

R33

R30

U4

R16

R12