Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
Copyright © 2000
Rev. 1.0a, 2005-02-07
WWW.Microsemi .COM
RangeMAX
™
LXM1621-xx
D
IGITAL
D
IMMING
D
UAL
L
AMP
CCFL
I
NVERTER
M
ODULE
P
RODUCTION
D
ATA
S
HEET
INTEGRATED PRODUCTS
DESCRIPTION
The LXM1621 Direct Drive™ CCFL
(Cold Cathode Fluorescent Lamp)
Inverter Modules are specifically
designed for driving two lamp LCD
backlight displays.
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 modules are
specifically designed with desktop and
industrial applications in mind.
Unlike the LXM1 620 or any trad itiona l
dimming CCFL inverters, the LXM1621
provides the designer a vastly superior
display brightness range. 100:1+
brightness range is achievable with a
standard LCD display (see Product
Highlight). Our wide range dimming
provides exceptio n al d isplay read ab ility at
less than 1% of full brightness, allowing
both power savings and low ambient light
operating capability(i.e. “night readab le”).
Digital dimming provides flicker-free
brightness control in any wide-range
dimming application.
Incorporation of a video synch-
ronization 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
the “How RangeMAX works” section).
The module design is based on a new
Direct Drive topology, which provides a
number of cost and performance
advantages.
Linfinity’s multiple lamp inverters
include a built in connector array for the
most common LCD lamp configurations.
Other benefits of this new topology are
fixed-frequency operation and secondary-
side strike-voltage regulation.
The LXM1621 is fully customizable
(electronically and mechanically) to
specific customer requirements.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
Protected By U.S. Patents: 5,923,129; 5,930,121; Patents Pending
KEY FEATURES
RangeMAX Wide Range Dimming
8V to 16V 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 Cab ins, 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 Vo lta g e
Regulation Minimizes Corona
Discharge For Long Life And High
Reliability
Power Efficien t, “Low Brightness”
Capability Allows Fo r Advanced
Power Management
PRODUCT HIGHLIGHT
123
W
123
W
D C V olt a g e
Source Potentiometer
UNIVERSAL D IMMING INPUT
V
DC
OR P OTENTIOMETER
MODULE ORDER INFO
P
ART
N
UMBER
L
AMP
C
URRENT
L
AMP RUN VOLTAGE
(RMS)
LXM1621-01
(UL60950 E175910)
7mA 500-750
LXM1621-02 6mA 350-550
LXM1621-03 6.5mA 350-550
LXM1621-04 5mA 470-640
L
LX
XM
M1
16
62
21
1-
-X
XX
X
BRITE
123
W
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
Copyright © 2000
Rev. 1.0a, 2005-02-07
WWW.Microsemi .COM
RangeMAX
™
LXM1621-xx
D
IGITAL
D
IMMING
D
UAL
L
AMP
CCFL
I
NVERTER
M
ODULE
P
RODUCTION
D
ATA
S
HEET
INTEGRATED PRODUCTS
ABSOLUTE MAXIMUM RATINGS (NOTE 1)
Input Supply Voltage (V
IN
)................................................................................................................................-0.3V to 18V
Output Voltage, no load....................................................................................................... Internally Limited to 1800V
RMS
Output Current........................................................................................................................10mA
RMS
(Internally Limited)
Output Power (pe r lam p) ..................................................................................................................................................6W
Input Signal Voltage (BRITE Input).................................................................................................................-0.3V to 6.5V
Input Signal Voltage (
SLEEP
, V
SYNC
)...............................................................................................................-0.3V to V
IN
Ambient Operating Temperature, zero airflow................................................................................................... 0°C to 70°C
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
specified terminal
RECOMMENDED OPERATING CONDITIONS
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.
Recommended Operating Conditions
Parameter Symbol
Min R.C. Max
Units
Input Supply Voltage Range (Functional) V
IN
8 12 16 V
Input Supply Voltage (Fully Regulated Lamp Current) 10.2 12 13.8 V
4 5 W
2.5 3 W
Output Power (Per Lamp) LXM1621-01
LXM1621-02 / 03
LXM1621-04 P
O
2.75 3.5 W
Brightness Control Input Voltage Range V
BRT_ADJ
0.0 2.5 V
500 625 750 V
RMS
350 425 500 V
RMS
Lamp Operating Voltage LXM1621-01
LXM1621-02 / 03
LXM1621-04 V
LAMP
470 550 640 V
RMS
7.0 mA
RMS
6.0 mA
RMS
6.5 mA
RMS
Lamp Current LXM1621-01
(Full Brightness – Per Lamp) LXM1621-02
LXM1621-03
LXM1621-04
I
OLAMP
5.0 MA
RMS
Operating Ambient Temperature Range T
A
0 70 °C
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, these specifications apply over the recommended operating conditions and 25°C ambient temperature for the LMX1621-xx.
LXM1621-xx
Parameter Symbol Test Conditions
Min Typ Max Units
` OUTPUT PIN CHARACTERISTICS
Full Brightness Current LXM1621-01 V
BRT_ADJ
= 2.5V
DC
,
SLEEP
= HIGH,
Burst Duty = 100%, V
IN
= 12V
DC
6.3 7.0 7.7 mA
RMS
LXM1621-02 V
BRT_ADJ
= 2.5V
DC
,
SLEEP
= HIGH,
Burst Duty = 100%, V
IN
= 12V
DC
5.5 6.0 6.5 mA
RMS
LXM1621-03 V
BRT_ADJ
= 2.5V
DC
,
SLEEP
= HIGH,
Burst Duty = 100%, V
IN
= 12V
DC
5.7 6.5 7.1 mA
RMS
LXM1621-04
I
L(MAX)
V
BRT_ADJ
= 2.5V
DC
,
SLEEP
= HIGH,
Burst Duty = 100%, V
IN
= 12V
DC
4.5 5.0 5.5 mA
RMS
V
BRT_ADJ
= 0V
DC
,
SLEEP
= HIGH,
Burst Duty = 2%, V
IN
= 9V
DC
0.14 mA
RMS
Minimum Lamp Current (Per Lamp)
(Notes 2 & 3) I
L(MIN)
V
BRT_ADJ
= -50mV
DC
,
SLEEP
= HIGH,
Burst Dut y =0.5%, V
IN
= 9V
DC
0.035 mA
RMS
Lamp Start Voltage V
LS
0°C < T
A
< 40°C, V
IN
> 10.8V
DC
1500 1800 V
RMS
Operating Frequency f
O
V
BRT_ADJ
= 2.5V
DC
,
SLEEP
= HIGH,
V
IN
= 12V
DC
52 57 62 kHz
E
EL
LE
EC
CT
TR
RI
IC
CA
AL
LS
S
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
Copyright © 2000
Rev. 1.0a, 2005-02-07
WWW.Microsemi .COM
RangeMAX
™
LXM1621-xx
D
IGITAL
D
IMMING
D
UAL
L
AMP
CCFL
I
NVERTER
M
ODULE
P
RODUCTION
D
ATA
S
HEET
INTEGRATED PRODUCTS
ELECTRICAL CHARACTERISTICS (CONTINUED)
Unless otherwise specified, these specifications apply over the recommended operating conditions and 25°C ambient temperature for the LMX1621-xx.
LMX1621-xx
Parameter Symbol Test Conditions
Min Typ Max Units
` BRITE INPUT
Input Current I
BRT
V
BRT_ADJ
= 0V -6 -8 -10 µA
DC
Input Voltage For Max. Lamp Current V
C
I
O(LAMP)
= 100% Duty Cycle 2.5 2.6 V
DC
I
O(LAMP)
= 2% Duty Cycle 0 0 V
DC
Input Voltage For Min. Lamp Current
(Note 3) V
C
I
O(LAMP)
= 0.5% Duty Cycle -50 mV
DC
`
SLEEP
INPUT
RUN Mode
(HI)SLEEP
V
2.2 V
IN
V
DC
SLEEP Mode
(LO)SLEEP
V
-0.3 0.8 V
DC
Input Current SLEEP
I
SLEEP
= 5.0V 70 75 100 µA
DC
` V
SYNC
CHARACTERISTICS
Logic High Level V
SYNC(HI)
4.0 6.5 V
DC
Logic Low Level V
SYNC(LO)
-0.3 1.0 V
DC
Input Impedance Z
IN
60 66 75
KΩ
Pulse Width (Note 4) t
PW
25 250 µs
Input Frequency f
SYNC
49 150 Hz
` POWER CHARACTERISTICS
Sleep Current I
IN(MIN)
V
IN
= 12V
DC
,
SLEEP
< 0.8V 5 50 µA
DC
Note 2: Minimum lamp current required to maintain even light output may vary with display panel.
Note 3: See 200:1 Dimming Application section for details.
Note 4: The module will be functional with pulse widths much larger than 250µs.
FUNCTIONAL PIN DESCRIPTION
Conn. Pin Description
CN1
CN1-1
CN1-2 V
IN
Input Power Supply (8V < V
IN
< 16V)
CN1-3
CN1-4 GND Power Supply Return
CN1-5 SLEEP ON / OFF Control. (2.2V < SLEEP < VIN = ON, -0.3V < SLEEP < 0.8V = OFF)
CN1-6 BRITE Brightness Control (-0.3V to 2.5V
DC
). 2.5V
DC
gives maximum lamp current.
CN1-7, 8 VSYNC Vertical synchronization input 49Hz < f
SYNC
< 150Hz
CN2 thru CN5: Refer to Connection Schematic Section
E
EL
LE
EC
CT
TR
RI
IC
CA
AL
LS
S
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
Copyright © 2000
Rev. 1.0a, 2005-02-07
WWW.Microsemi .COM
RangeMAX
™
LXM1621-xx
D
IGITAL
D
IMMING
D
UAL
L
AMP
CCFL
I
NVERTER
M
ODULE
P
RODUCTION
D
ATA
S
HEET
INTEGRATED PRODUCTS
PHYSICAL DIMENSIONS
LXM1621-01 / 02 / 03
38mm
1.50 in
48mm
1.89 in
32mm
1.26 in.
124mm
4.88 in
CN2 CN3
W
Warning
High Voltage Present at
all Output Connectors
Weight: 23 (g) typ.
CN1
Backside
Connectors
CN2, CN3
6mm
0.24 in
∅3.0mm ±0.08
(0.12in)
Grounded Mount ing Hole - 2plcs
1.52mm
0.60 in
PCB tolerances ±0.5mm
W
CN4 CN5
W
W
LXM1621-04
38mm
1.50 in
48mm
1.89 in
32mm
1.26 in.
124mm
4.88 in
CN2 CN3
W
Warning
High Voltage Present at
all Output Connectors
Weight: 23 (g) typ.
CN1
Backside
Connectors
CN2, CN3
6mm
0.24 in
∅3.0mm ±0.08
(0.12in)
Grounded Mounting Hole - 2plcs
1.52mm
0.60 in
PCB tolerances ±0.5mm
W
All dimensions are in inches ( mm)
M
ME
EC
CH
HA
AN
NI
IC
CA
AL
LS
S
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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Copyright © 2000
Rev. 1.0a, 2005-02-07
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RangeMAX
™
LXM1621-xx
D
IGITAL
D
IMMING
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UAL
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AMP
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NVERTER
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ODULE
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ATA
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INTEGRATED PRODUCTS
TYPICAL CONNECTION CONFIGURATIONS
CN1
CN4
CN5
LXM1621-01 / 02 /03
CCFL Lamps
Desktop Display
CN1
CN4
CN5
LXM1621-01 / 02 /03
CCFL Lamps
Desktop Display
CN1
CN4
CN5
LXM1621-01 / 02 /03
CCFL Lamps
Desktop Display
CCFL Lam ps
Desktop D isplay
CN1
CN2
CN3
LXM1621-01 / 02 /03
CN1
CN2
CN3
LXM1621-04
CCFL Lamps
Desktop Display
CN1
CN2
CN3
LXM1621-04
CCFL Lamps
Desktop Display
* Connectors CN2 and CN3 are on the bottom side of the inverter. View shown is looking through the board
Figure 1
–
Connectivity Configuration Examples
These examples illustrate six typical LCD wiring configurations that are accommodated by Linfinity’s unique connector array.
Linfinity inverters have multiple lamp connector styles that re common to the industry, which are duplicated at both ends of the
module. This permits over 14 variations of module mounting and interconnectivity configuration.
P
PA
AC
CK
KA
AG
GE
E
D
DA
AT
TA
A
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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Rev. 1.0a, 2005-02-07
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RangeMAX
™
LXM1621-xx
D
IGITAL
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IMMING
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UAL
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AMP
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ATA
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INTEGRATED PRODUCTS
CONNECTION SCHEMATIC
CN1
W
CN4
W
CN5
Inverter
Output 1
Inverter
Output 2
V
HI1
V
HI2
CN2 CN3
1
2
31
2
3
N.C.
N.C.
1
2
3
4
4
3
2
1
W
W
Figure 2a
–
LXM1621-01 / 02 / 03 Connection Schematic
CN1
W
CN2
W
CN3
Inverter
Output 1
Inverter
Output 2
V
HI1
V
HI2
1
2
3
3
2
1
Figure 2b
–
LXM1621-04 Connection Schem atic
Connectors: Mates With
CN1
Molex 53261-0890 Pins: 50079-8100*, Ho using: 51021-0800
*Loose(-8000, Chain) Recommended #26 AwG wiring
Connection for LX M1621-01 / 02 / 03
CN2, CN3
JST SM04(4.0)B-BHS-1-TB or Yeon Ho 2 0015WR-07A00 JST BHR-04VS-1
CN4, CN5
JST SM03(4.0)B-BHS-1-TB or Yeon Ho 2 0015WR-05A01 JST BHR-03VS-1
Connection for LXM1621-04
CN2, CN3
JST SM03(4.0)B-BHS-1-TB or Yeon Ho 2 0015WR-05A01 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 LXM1621-01 / 02 / 03 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.
3. The LXM1621-04 uses the reverse pinout found in some panels. The lamp hot wires (high voltage wires) are on pins 2 and 3 and
the cold (low voltage wire) is on pin 1.
P
PA
AC
CK
KA
AG
GE
E
D
DA
AT
TA
A
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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RangeMAX
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LXM1621-xx
D
IGITAL
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IMMING
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UAL
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AMP
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ATA
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HOW THE RANGEMAX WORKS
LAMP VOLTAGE & LAMP CURRENT – BURST MODE OP ERATION
Figure 3 – 50% Burst Duty Cycle
Figure 4 – 2% Burst Duty Cycle
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 fu ll brightness.
As can be seen in Trace 3 of Figure 5 photo at right, 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.
Figure 5 – 2% Burst Duty Cycle (Expanded Time Base)
Ramp Gen. Transformer
Driver
High Voltage
Transformer
Comparator
Ramp +
-
I
SENSE
V
SENSE
V
BRITE
0.25 -
2.2V
DC
V
SYNC
LAMP
V
LO
V
HI
LAMP
V
LO
V
HI
Figure 6
– RangeMAX Simplified Block Dia gram
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 ex ternally ind uc ed no ise, which
can cause lamp flicker.
• An on-board oscillator operates the inverter BURST rate
about 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 freq uency synchronized to th e video frame
rate. This provides operation with no visible display
disturbances caused by beat frequencies between the
lamps and video frame rates.
D
DE
ES
SC
CR
RI
IP
PT
TI
IO
ON
N
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IGITAL
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IMMING
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AMP
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ATA
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INTEGRATED PRODUCTS
HOW THE RANGEMAX WORKS (CONTINUED)
HIGHLIGHTS (CONTI NUE D )
• 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 ov er-voltage prev ention w ith broken
or failed lamps, and accurate lamp current regulation.
TYPICAL APPLICATION
• The brightness control may be a simple 10k po tentiometer
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 8.
• If synchronization to the video frame rate is desired,
connect the vertical sync pulse from the system video
controller to the appropriate V
SYNC
input. If no video
synchronization is desired, connect V
SYNC
to ground.
• If you need to turn the inverter ON/OFF remotely, conn ect
a 3V or 5V logic signal to the SLEEP input. If remote
ON/OF F is not need ed, connec t the
SLEEP
input to V
IN
or
any other voltage greater than 2.2V
DC
.
• Connect V
HI
to high voltage wire from the lamp. Connect
V
LO
to the low voltag e wire (wire with thinner insulatio n).
If both lamp wires have heavy high voltage insulation,
connect the longest wire to V
LO
. V
LO
is connected directly
to ground (GND pin) on the inverter PCB. Always insure
a good lamp return by using a wire. Do not rely on a
chassis ground connection
.
RangeMAX INVERTERS
Also available in single lamp inverters are the
LXM1612-xx-xx or LXM1615-xx-xx, as well as the
12V dual lamp LXM1621-12-xx, LXM1622-xx-xx, and
the Quad output LXM1641-01 versions for multiple
lamp applications.
LXM1621-xx
12V
V
SYNC
V
SYNC
GND
V
HI1
V
LO
BRITE
Figure 7- Brightness Control
V
IN
SLEEP
5V
0
< 10k
2.5V
DC
V
HI2
P.W.
< 100µs
BRITE
LXM1621-xx
0 < P.W. < 100% of period
PWM Signal
from Sy stem
Figure 8 - PWM Brightness Control
4.7µF
4.99k*
4.99k
* use 4.99k for 5V PWM amplitude, 15k for 3.3V PWM
amplitude, and o m it for 2.5V PWM amplitute.
A
AP
PP
PL
LI
IC
CA
AT
TI
IO
ON
NS
S
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IGITAL
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AMP
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WIDER DIMMING APPLICATION
The following application defines techniques capable of
delivering dimming ranges in the 250:1 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 (250:1) 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 then –300mV to any inverter input will cause
inverter malfunction (see Absolute Maximum Ratings).
-100mV 0V 2.5V
.070
.14
0.7
7
V
BRT_ADJ
(V)
I
OLAMP
(mA)
Figure 9 – Average Lamp Current vs. V
BRITE
Voltage (per Lamp)
CN2
C30
U9
T1
R58
C32
C33
R59
C35
R22
R48
R62
R63 R60
R31
R57
R55R52
R54
R53
R56
R51
Q11
R50
C39
R49
R89
C37
R61
Q10
Backside of Module
U7
Figure 10 – Locating The Resistor on the LXM162 1-xx
2. By making a resistor value change on the module.
Remove R61 for maximum dimming range or increase R61
value to desired minimum dim range setting (see figure 10).
Care should be exercised since at a low enough dim setting the
inverter will be unable to detect that the lamp has started and
will initiate lamp strike (kickoff) voltage. This will result in
lamp flicker. For repeatable low light levels the BRITE input
DC supply must be a very clean stable voltage source, at low
dim inputs.
If you plan to completely remove R61 it is recommended tha
t
you ensure that a minimum voltage above zero remain on the
BRITE input to prevent the above flicker problem. This
minimum voltage may need to be adjusted for each individual
inverter module. If you are using a pot to control the BRITE
input then a separate trim pot o n the low side would accomplish
the same goal.
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 regard to display
quality at these dimming levels. At very low brightness levels,
even very small amounts of noise on the VBRITE line can cause
flicker on the display, so special care must be given to
grounding, filtering, and shielding the inverter from the digital
logic and clock signals.
A
AP
PP
PL
LI
IC
CA
AT
TI
IO
ON
NS
S
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 10
Copyright © 2000
Rev. 1.0a, 2005-02-07
WWW.Microsemi .COM
RangeMAX
™
LXM1621-xx
D
IGITAL
D
IMMING
D
UAL
L
AMP
CCFL
I
NVERTER
M
ODULE
P
RODUCTION
D
ATA
S
HEET
INTEGRATED PRODUCTS
NOTES
Preliminary Data – Information contained in this document is pre-production data and is
proprietary to LinFinity. It may not be 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.
N
NO
OT
TE
ES
S
