Datasheet LXM1621-02, LXM1621-01, LXM1621-03 Datasheet (Microsemi Corporation)

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DESCRIPTION KEY FEATURES

RangeMAX Wide Range Dimming, Dual
Output Inverter. The LXM1621 Direct

DriveTM CCFL (Cold Cathode Fluorescent
Lamp) Inverter Modules are specifically de­signed for driving LCD backlight lamps.

Similar to the LXM1620, the LXM1621 ex­cels in applications where critical parameters
include very wide range dimmability, high ef­ficiency and reliable fail-safe design in a small
form factor. These 12 volt input modules are
specifically designed with desktop and indus­trial applications in mind.

Unlike the LXM1620 or any traditional
dimming CCFL inverters, the LXM1621 pro­vides the designer a vastly superior display
brightness range. 1000:1+ brightness range
is achievable with a standard LCD display (see
Product Highlight). Our wide range dimming
provides exceptional display readability at less
than 1% of full brightness, allowing both
power savings and low ambient light operat­ing capability (i.e. "night readable").

RangeMAX Digital Dimming Tech­nique. Digital dimming provides flicker-free

brightness control in any wide-range dimming
application. Dimming ratios as great as
1000:1 can be achieved. Incorporation of a
video synchronization feature allows wide
ratio dimming without the display distur­bances and interference seen with competi­tive products.

The modules are equipped with a dimming
input that permits brightness control from an
external potentiometer or DC voltage source.
The resultant "burst drive" that energizes the

lamp was designed specifically to ensure that
no premature lamp degradation occurs (see
"How RangeMAX Works" Section).

Fail-safe Feature For Multiple Lamp

Applications. Our multi-output inverters are

designed to keep your application operating
at near normal brightness in the event that a
lamp fails. This allows the display to remain
"on-line" until lamp replacement is conve­nient.

Direct Drive Technology. The module

design is based on a new Direct Drive topol­ogy, which provides a number of cost and
performance advantages. The LXM1621-xx
Direct Drive inverters eliminate the classic
resonant inductor and capacitors, thus reduc­ing cost and allowing a substantial reduction
in module size.

Universal Connector Configuration.

Linfinity's multiple lamp inverters include a
built in connector array for the most com­mon LCD lamp configurations.

Additional Features. Other benefits of

this new topology are fixed-frequency opera­tion and secondary-side strike-voltage regu­lation.

Strike-voltage regulation minimizes corona
discharge in the output transformer and re­lated circuitry, providing longer life and higher
reliability. All LXM1621 modules feature
both open and shorted lamp protection.

The LXM1621 is fully customizable (elec­tronically and mechanically) to specific cus­tomer requirements.

TM

RangeMAX

LXM1621-xx

DIGITAL DIMMING DUAL LAMP CCFL INVERTER MODULE

P RELIMINARY DATA SHEET

■ RangeMAX Wide Range Dimming

■ 8V To 18V Input Voltage Range

■ Small Form Factor

■ Easy To Use Brightness Control

■ MicroAmp SLEEP Mode

■ Output Short-Circuit Protection And

Automatic Strike-Voltage Regulation

■ Fixed Frequency Operation

■ Universal Connector Configuration

APPLICATIONS

■ Hi-Brite Displays

■ Desktop Displays

■ Low Ambient Light Conditions (i.e. Aircraft

Cabins, Automobile)

■ Industrial Applications

BENEFITS

■ High Efficiency Reduces Heating Problems

■ Smooth, Flicker Free 0-100% Full-Range

Brightness Control Gives Your Product A
High Quality Image

■ Output Open Circuit Voltage Regulation
Minimizes Corona Discharge For Long Life
And High Reliability

■ Power Efficient, "Low Brightness" Capability
Allows For Advanced Power Management

Copyright © 2000
Rev. 0.6 2/00

NOTE: For current data & package dimensions, visit our web site: http://www.linfinity.com.

MODULE ORDER INFORMATION

Part Number Lamp Run Voltage Lamp Current

LXM1621-01 500 - 750V

LXM1621-02 350 - 500V

LXM1621-03 350 - 500V

RMS

RMS

RMS

7mA

6mA

6.5mA

L INF INITY MICROELECTRONICS INC.

11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: [phone]

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PRODUCT DATABOOK 1996/1997

LXM1621-xx

RangeMAX

DIGITAL DIMMING DUAL LAMP CCFL INVERTER MODULE

P RELIMINARY DATA SHEET

ABSOLUTE MAXIMUM RATINGS (Note 1)

Input Supply Voltage (VIN)........................................................................................................................................................ -0.3V to 18V

Output Voltage, no load .............................................................................................................................. Internally Limited to 1800V

Output Current ............................................................................................................................................. 10.0mA

Output Power (per Lamp) .................................................................................................................................................................... 6.0W

Input Signal Voltage (BRITE Input) ....................................................................................................................................... -0.3V to 6.5V

Input Signal Voltage (SLEEP, V

Ambient Operating Temperature .................................................................................................................................................... 0°C to 70°C

Inputs) ................................................................................................................................... -0.3V to V

SYNC

Storage Temperature Range .........................................................................................................................................................-40°C to 85°C

Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground.

Currents are positive into, negative out of the specified terminal.

RECOMMENDED OPERATING CONDITIONS (R.C.)

This module has been designed to operate over a wide range of input and output conditions. However, best efficiency and performance
will be obtained if the module is operated under the condition listed in the 'R.C.' column. Min. and Max. columns indicate values beyond
which the inverter, although operational, will not function optimally.

Parameter

Symbol

Input Supply Voltage Range (Functional) V
Input Supply Voltage (Fully Regulated Lamp Current)
Output Power (per Lamp) LXM1621-01 P

LXM1621-02/-03

Brightness Control Input Voltage Range V
Lamp Operating Voltage LXM1621-01 V

LXM1621-02/-03

Lamp Current (Full Brightness - per Lamp) LXM1621-01 I

LXM1621-02
LXM1621-03

Operating Ambient Temperature Range T

IN

O

BRT ADJ

LAMP

OLAMP

A

Recommended Operating Conditions

Min. R.C. Max.

81218V

10.2 12 13.8 V
45W

2.5 3 W

0.0 2.5 V
500 625 750 V

350 425 500 V

7.0 mA

6.0 mA

6.5 mA

070°C

(Internally Limited)

RMS

TM

RMS

IN

Units

RMS

RMS

RMS

RMS

RMS

ELECTRICAL CHARACTERISTICS

Unless otherwise specified, these specifications apply over the recommended operating conditions and 25°C ambient temperature for the LXM1621-xx.

Parameter

Symbol

Test Conditions Units

LXM1621-xx

Min. Typ. Max.

Output Pin Characteristics

Full Bright Lamp Current 1621-01 I

(per Lamp)

1621-02 V

L (MAX)VBRT ADJ

1621-03 V

Minimum Lamp Current (per Lamp) I

L (MIN)VBRT ADJ

(Notes 2 & 3) V
Lamp Start Voltage V
Operating Frequency f

LS

O

= 2.5VDC, SLEEP = HIGH,

= 2. 5VDC, SLEEP = HIGH,

BRT ADJ

= 2. 5VDC, SLEEP = HIGH,

BRT ADJ

Burst Duty = 100%, VIN = 12V

Burst Duty = 100%, VIN = 12V

Burst Duty = 100%, VIN = 12V
= 0VDC, SLEEP = HIGH, Burst Duty = 2%, VIN = 9V
= -50mVDC, SLEEP = HIGH,

BRT ADJ

0°C < TA < 40°C, VIN ≥ 10.8V
V

= 2.5VDC, SLEEP = HIGH, VIN = 12V

BRT ADJ

Burst Duty = 0.5%, VIN = 9V

DC

DC

6.3 7.0 7.7 mA

DC

5.5 6.0 6.5 mA

DC

5.7 6.5 7.1 mA

DC

DC

DC

0.14 mA

0.035 mA

1500 1800 V

52 57 62 KHz

BRITE Input

Input Current I
Input Voltage for Max. Lamp Current V
Input Voltage for Min. Lamp Current V

(Note 3) I

V

BRT

C

C

= 0V

BRT ADJ

I

O (LAMP)

I

O (LAMP)

O (LAMP)

DC

= 100% Duty Cycle
= 2% Duty Cycle
= 0.5% Duty Cycle

-6 -8 -10 µA

2.5 2.6 V
00V

-50 mV

SLEEP Input

RUN Mode V
SLEEP Mode V
Input Current I

SLEEP (HI)

SLEEP (LO)

SLEEP

SLEEP = 5.0V

Note 2. Minimum lamp current required to maintain even light output may vary with display panel.

3. See 1000:1 Dimming Application section for details.

2.2 V

-0.3 0.8 V
70 75 100 µA

RMS

RMS

RMS

RMS

RMS

RMS

DC

DC

DC

DC

V

IN

DC

DC

DC

2

Copyright © 2000

Rev. 0.6 2/00

PRODUCT DATABOOK 1996/1997

P ATENT PENDING

TM

RangeMAX

DIGITAL DIMMING DUAL LAMP CCFL INVERTER MODULE

P RELIMINARY DATA SHEET

ELECTRICAL CHARACTERISTICS (Continued)

Parameter

V

Characteristics

SYNC

Logic High Level V
Logic Low Level V
Input Impedance Z
Pulse Width (Note 4) t
Input Frequency f

Power Characteristics

Sleep Current I

Note 4. The module will be functional with pulse widths much larger than 250µs.

Conn. Pin Description

CN1

CN1-1
CN1-2

CN1-3
CN1-4

CN1-5 SLEEP

CN1-6 BRITE

CN1-7, 8

V

IN

GND

V

SYNC

Input Power Supply. (8V ≤ VIN ≤ 18V)

Power Supply Return.

ON/OFF Control. (2.2V < SLEEP < VIN = ON, -0.3V < SLEEP < 0.8V = OFF)

Brightness Control (-0.3V to 2.5V

Vertical syncronization input. 49Hz < f

CN2 thru CN5: Refer to Figure 2

Symbol

SYNC (HI)

SYNC (LO)

IN

PW

SYNC

IN (MIN)VIN

= 12VDC , SLEEP ≤ 0.8V

FUNCTIONAL PIN DESCRIPTION

). 2.5VDC gives maximum lamp current.

DC

SYNC

LXM1621-xx

Test Conditions Units

< 150Hz

LXM1621-xx

Min. Typ. Max.

4.0 6.5 V

-0.3 1.0 V
60 66 75 kΩ
25 250 µs
49 150 Hz

550µA

DC

DC

DC

Copyright © 2000
Rev. 0.6 2/00

CN2

(Bottom Side)

0.24 (6)

0.338 (8.6) Max.

PHYSICAL DIMENSIONS

All dimensions are in inches (mm)

CN4

1.50 (38) 1.89 (48)

0.060 (1.52) max.

LXM1621-xx

4.88 (124)

CN1

CN3

(Bottom Side)

1.26
(32)

CN5

Ø 0.12 (3.0)

Grounded Mounting Hole - 2 plcs

Warning!!

High Voltage Present

At All Output

Connectors

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LXM1621-xx

CCFL Lamps

Desktop Display

CCFL Lamps

LXM1621-xx

Desktop Display

CCFL Lamps

Desktop Display

LXM1621-xx*

CCFL Lamps

Desktop Display

CN5

CN4

CN1

CN5

CN4

CN1

CN1

CN2

CN3

*

Connectors CN2 and CN3 are on the bottom side of the inverter. View shown is looking through the board.

LXM1621-xx

CN5

CN4

CN1

PRODUCT DATABOOK 1996/1997

LXM1621-xx

TM

RangeMAX

DIGITAL DIMMING DUAL LAMP CCFL INVERTER MODULE

P RELIMINARY DATA SHEET

TYPICAL CONNECTION CONFIGURATIONS

FIGURE 1 — Connectivity Configuration Examples

These examples illustrate four typical LCD wiring configurations
that are accomodated by Linfinity's unique connector array.
Linfinity inverters have multiple lamp connector styles that are
common to the industry, which are duplicated at both ends of the
module. This permits over 12 variations of module mounting and
interconnectivity configurations.

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Copyright © 2000

Rev. 0.6 2/00

PRODUCT DATABOOK 1996/1997

I

S

Lamps

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RangeMAX

Note: CN2 and CN3 (shown with dashed lines) are located on the opposite side of the PCB from CN1, CN4

Connectors: Mates With:
CN1 = MOLEX 53261-0890 Pins: 50079-8100*, Housing: 51021-0800

TM

LXM1621-xx

DIGITAL DIMMING DUAL LAMP CCFL INVERTER MODULE

P RELIMINARY DATA SHEET

CONNECTOR SCHEMATIC

CN1

81

4

N.C.

3

V

2

1

CN2 CN3

1

2

3

CN4

FIGURE 2 — LXM1621-xx Connector Schematic

and CN5. Their pin numbers are shown as viewed looking through the printed circuit board.

HI1

Inverter

Output 1

V

HI2

Inverter

Output 2

* Loose (-8000, Chain) Recommended #26 AWG wiring

3

2

1

CN5

N.C.

1

2

3

4

CN2, CN3 = JST SM04(4.0)B-BHS-1-TB JST BHR-04VS-1

CN4, CN5 = JST SM03(4.0)B-BHS-1-TB JST BHR-03VS-1

Connection Rules

1. Always install two (2) lamps. Operating with only one lamp may overdrive lamp current at maximum brightness settings.

2. Verify lamp wiring before connecting lamps to the inverter module. Connecting both lamps to one of the two inverter output circuits

will result in reduced brightness. The LXM1621-xx module connectors are wired per industry standard. The lamp hot wires (high voltage wires)
are always on pin 1 or 2, and the cold wire (low voltage wire) is always on pin 3 or 4.

FAILSAFE FEATURE FOR MULTIPLE LAMP OPERATIONS

Our multi-output inverters are designed to keep your application
operating at near normal brightness in the event that a lamp fails.
This allows the display to remain "on-line" until lamp replacement
is convenient.

Linfinity "pairs" the lamps so that if one lamp in the pair breaks,
most of its current is added to the good lamp. CCFLs will respond
with more brightness for a period of time. Operating time in this
mode will be a function of the lamps age but should be typically
in the order of hundreds of hours.

This operating characteristic can provide adequate display
performance for a limited, but useful period of time. Shortening
of the lamp life in this mode is typically not a concern as it is
recommended that all lamps in a display be replaced at the same
time.

FIGURE 3 — Dual Output Stage

Copyright © 2000
Rev. 0.6 2/00

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DIGITAL DIMMING DUAL LAMP CCFL INVERTER MODULE

P RELIMINARY DATA SHEET

HOW RANGEMAX WORKS

LAMP VOLTAGE & LAMP CURRENT — Burst Mode Operation

(770V

(7.6mA

FIGURE 4 — 50% Burst Duty Cycle FIGURE 5 — 2% Burst Duty Cycle

TM

RangeMAX

(760V

(6.7mA

)

RMS

)

RMS

)

RMS

)

RMS

Rather than using the traditional dimming technique of
varying lamp current magnitude to adjust light output,
RangeMAX inverters use a fixed lamp current value with
a duty cycle control method.

The lamp current burst width can be modulated from
100% (continuous lamp current) down to a 2% duty cycle,
allowing the lamp to be dimmed to less than 1% of its
full brightness.

As can be seen in Trace 4 of Figure 6, careful design
consideration was given to controlling lamp start voltage
to softly start current flow. This eliminates current over­shoot that can result in premature cathode wear and re­duce lamp life.

Comparator

V

BRITE

0-2.5V

DC

Ramp

Ramp

Gen.

Transformer

Driver

FIGURE 6 — 2% Burst Duty Cycle (Expanded Time Base)

High Voltage

Transformer

V

HI1

LAMP 1

V

SENSE

(760V

(6.7mA

)

RMS

)

RMS

V

SYNC

I

SENSE

V

LO

FIGURE 7 — RangeMAX Block Diagram

6

Copyright © 2000

Rev. 0.6 2/00

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RangeMAX

DIGITAL DIMMING DUAL LAMP CCFL INVERTER MODULE

P RELIMINARY DATA SHEET

HOW RANGEMAX WORKS (continued)

HIGHLIGHTS

■ On-board 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.

■ An on-board oscillator operates the inverter BURST rate

above 95Hz, well beyond standard 50/60Hz video refresh
rates where the eye can perceive pulsing light.

■ 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.

TYPICAL 100:1 DIMMING APPLICATION

LXM1621-xx

■ In applications with no access to a vertical sync, the in­verter burst frequency can be allowed to "free run" at 95Hz.
In this non-synchronous mode, minor display disturbances
may be found under certain video conditions. This per­formance is acceptable for many applications, but synchro­nization must be used when no disturbance can be toler­ated.

■ 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.

2.5V

£ 10k

DC

BRITE

8VDC- 18V

V

IN

LXM1621-xx

5V

0V

V

SYNC

FIGURE 8 — Potentiometer Brightness Control

PWM Signal

from System

P.W.

£

100µs

0 £ P.W. £ 100% of period

* use 4.99k for 5V PWM amplitude, 15k for 3.3V PWM
amplitude, and omit for 2.5V PWM amplitude.

SLEEP

V

SYNC

4.99k

4.99k*

DC

GND

4.7µF

■ The brightness control may be a simple 10k
potentiometer or a voltage output DAC. A PWM signal
from a micro-controller may also be used with a suitable
filter such as shown in Figure 8A.

V

HI2

V

HI1

Lamp 1

Lamp 2

V

LO

■ If synchronization to the video framerate is desired,
connect the vertical sync pulse from the system video
controller to the appropriate V
synchronization is desired, connect V

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

input. If no video

SYNC

to ground.

SYNC

a 3V or 5V logic signal to the SLEEP input. If remote ON/
OFF is not needed, connect the SLEEP input to V
other voltage greater than 2.2V

■ Connect V
Connect VLO to the low voltage wire (wire with thinner

to high voltage wire from the lamp.

HI

.

DC

or any

IN

insulation). If both lamp wires have heavy high voltage
insulation, connect the longest wire to V
connected directly to ground (GND pin) on the inverter

. VLO is

LO

PCB. Always insure a good lamp return by using a
wire. Do not rely on a chassis ground connection.

BRITE

LXM1621-xx

Copyright © 2000
Rev. 0.6 2/00

FIGURE 8A — PWM Brightness Control

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LXM1621-xx

DIGITAL DIMMING DUAL LAMP CCFL INVERTER MODULE

P RELIMINARY DATA SHEET

1000:1 DIMMING APPLICATION

The following application defines techniques capable of deliver­ing dimming ranges in the 250:1 and 1000:1 range. As is widely
understood, these techniques will provide general capabilities and actual
system performance will vary with panel design, CCFTs, ambient tem­perature and a number of other variables outside the control of the
inverter. These methods can be used in conjunction with other tech­niques such as lamp heating and matching.

Wide ratio (1000:1) dimming can be accomplished using the
Linfinity inverter in two ways:

1) By varying the input voltage on the brightness pin as
indicated in Figure 9. Caution must be exercised when
applying negative voltage to the brightness control input.
Applying more than -300mV to any inverter input will cause
inverter malfunction (see Absolute Maximum Ratings).

RangeMAX

7

(mA)

0.7

OLAMP

I

.14

.070

0V 2.5V-100mV

V

(V)

BRT ADJ

FIGURE 9 — Average Lamp Current vs. V

(per Lamp)

Voltage

BRITE

TM

2) By making a resistor value change on the module. If this
option is preferrable, please contact the factory for applica­tion assistance.

Both methods discussed will provide a lower duty cycle

operation than is necessary in a 100:1 dimming application.

Careful consideration should be made with regards to display
quality at these dimming levels. At very low brightness levels,
even very small amounts of noise on the V
flicker on the display, so special care must be given to grounding,

line can cause

BRITE

filtering and shielding the inverter from the digital logic and clock.

RangeMAX INVERTERS

Also available in Single

Output LXM1611-01,

LXM1612-xx or Quad Output

LXM1641-01 versions for

multiple lamp applications.

RangeMAX and Direct Drive are trademarks of Linfinity Microelectronics Inc.

PRELIMINARY DATA - Information contained in this document is pre-production data, and is proprietary to LinFinity. It may
not modified in any way without the express written consent of LinFinity. Product referred to herein is offered in sample form
only, and Linfinity reserves the right to change or discontinue this proposed product at any time.

8

Copyright © 2000

Rev. 0.6 2/00