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LXM1597-01
5V CCFL INVERTER MODULES
1597
THE INFINITE POWER OF INNOVATION
DESCRIPTION
LXM1597-01 CCFL (cold cathode florescent
lamp) Inverter Modules are specifically designed for driving LCD back light lamps in
applications where dimmability, ultra-high
efficiency, high light output, low noise emissions, reliable fail safe design, and small form
factors are critical parameters. Both monochrome and color displays are supported.
The modules convert unregulated DC
voltage from the system battery or AC
adapter directly to high-frequency, highvoltage sine waves required to ignite and
operate CCFL lamps. The module design is
based on a proprietary Linfinity IC that provides important new performance advances.
Remarkable improvements in efficiency
and RF emissions result from its single stage
resonant inverter featuring a patent pend-
Current Synchronous, Zero Voltage
ing
Switching (CS-ZVS) topology. CS-ZVS produces nearly pure sine wave currents in the
lamp enabling maximum light delivery while
reducing both conducted and radiated noise.
This topology simultaneously performs
lation, lamp current regulation, and lamp
dimming in a single power stage made up
of two pairs of low loss FET's. The FET's
drive an LC resonant circuit that feeds the
primary of a high voltage transformer with
a sinusoidal voltage.
Required L and C values in the resonant
circuit are such that very low loss components can be used to obtain higher electrical efficiency than is possible with previous
topologies.
The full bridge LXM1597-01 is optimized
to efficiently operate with up to 4 watt lamps
at input voltages of 5 volts. This module
will operate over the full 4.5V to 7V input
voltage range.
The modules are equipped with a dimming input that permits full range brightness control from an external potentiometer, and a sleep input that reduces module
power to a few microwatts in shut down
mode.
All modules feature output open and short
circuit protection.
three tasks consisting of line voltage regu-
IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.
PRODUCT HIGHLIGHT
BACKLIGHT INVERTER LIGHT OUTPUT EFFICIENCY COMPARISON
50
45
40
35
30
25
20
Eff (Nits / Watts)
15
10
5
0
Not recommended for New Designs
KEY FEATURES
■ 15 to 30% More Light Output
■ Closed Loop, Fully Regulating Design
■ 4.5V To 7V Input Voltage Range
■ Versatile Brightness Control Input
■ 3 MicroAMP Sleep Current
■ Output Short Circuit Protection And
Automatic Over-Voltage Limiting
■ 8mm Max. Height, Narrow Footprints
■ Single Sided PCB Is Self Insulating
APPLICATIONS
■■
■ Notebook And Sub-Notebook Computers
■■
■ Personal Digital Assistants
■ Portable Instrumentation
■ Automotive Displays
■ Desktop Displays
■ Airline Entertainment Centers
BENEFITS
■ Ultra-High Efficiency, Line Voltage
Regulation And Sleep Mode Extend
Computer Battery Life
■ Cool Operation PermitS Close Proximity
To LCD Panel Without Display Distortion
■ Smooth, Full-Range Brightness Control
Gives Your Product A High Quality Image
■ Low EMI / RFI Design Minimizes Shielding
Requirements
■ Narrow, Low-Profile Standard Modules Fit
Into Most LCD Enclosures
■ Single Sided PCB Saves Expensive High
Voltage Insulating Tapes
Linfinity
Copyright © 1998
Rev. 0.6a 10/00
Computer 1
Computer 2
Computer 3
Stock
MODULE ORDER INFO
5V INPUT
LXM1597-01
L INFINITY MICROELECTRONICS INC.
11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: 714-893-2570
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PRODUCT DATABOOK 1996/1997
LXM1597-01
5V CCFL INVERTER MODULES
Not Recommended for New Designs
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage (VIN) ............................................................................................................................................................................... -0.3V to 7.0V
Output Voltage, no load ........................................................................................................................................................ Internally Limited to 1900V
Output Current......................................................................................................................................................................... 8.0mA
Output Power .................................................................................................................................................................................................................. 4.2W
Input Signal Voltage, (SLEEP and BRITE Inputs)............................................................................................................................................ -0.3V to 6.5V
Ambient Operating Temperature, zero airflow .................................................................................................................................................. 0°C to 60°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
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 V
Output Power P
Brightness Control Input Voltage Range V
Lamp Operating Voltage V
Lamp Current - Full Brightness I
Operating Ambient Temperature Range T
IN
O
BRITE
LAMP
OLAMP
A
Recommended Operating Conditions
Min. R.C. Max.
4.5 5 7 V
2.5 4.0 W
0.8 2.5 V
240 500 650 V
57mA
060°C
(Internally Limited)
RMS
RMS
Units
RMS
RMS
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, these specifications apply over the recommended operating conditions and 25°C ambient temperature for the LXM1597.
Parameter
Symbol
Test Conditions Units
LXM1597
Min. Typ. Max.
Output Pin Characteristics
Full Bright Lamp Current I
Minimum Lamp Current I
Lamp Start Voltage V
Operating Frequency f
L (MAX)VBRITE
L (MIN)VBRITE
LS
O
= 2.5 VDC, SLEEP = Logic High
= 0.8 VDC, SLEEP = Logic High
0°C < TA < 60°C
V
= 2.5VDC, SLEEP = Logic High, VIN = 5V
BRITE
6.2 6.6 7.0 mA
2.6 mA
1300 V
50 KHz
RMS
RMS
Brightness Control
Input Current I
BRITEVBRITE
Input Voltage for Max. Lamp Current VCI
Input Voltage for 50% Lamp Current V
CIO (LAMP)
= 0V
O (LAMP)
DC
= 100%
= 50%
-200 -1000 nA
2.4 2.5 2.6 V
1.25 V
DC
DC
DC
SLEEP Input
Input Logic 1 V
Input Logc 0 V
Input Current I
IH
IL
V
IN
= 0 - 5V
SLEEP
DC
2.2 5.5 V
0 0.8 V
50 100 µA
DC
DC
DC
Voltage Reference
Output Voltage V
Output Current I
0 < I
REF
REF
< 500µA
REF
2.40 2.50 2.60 V
500 µA
DC
DC
Power Characteristics
Sleep Current I
IN (MIN)VIN
Electrical Efficiency (calculated values) η LXM1597, V
= 5VDC , SLEEP = Logic 0
= 5VDC, I
IN
O (LAMP)
= 5mA
RMS
310µA
DC
90 %
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Copyright © 1998
Rev. 0.6a 10/00
Page 3
PRODUCT DATABOOK 1996/1997
5V CCFL INVERTER MODULES
Conn. Pin Description
CN1
CN1-1
CN1-2
CN1-3
CN1-4
CN1-5
CN1-6
CN1-7
CN1-8
CN2
CN2-1
CN2-2
V
IN
GND Power supply return.
SLEEP Logical high on this pin enables inverter operation. Logical low removes power from the module and
BRITE Brightness control input. Apply 0.8 to 2.5 volts DC to control lamp brightness. Lamp current varies
AGND Brightness control signal return. For best results do not run 5V power supply current return through this pin.
V
REF
LAMP LO High voltage connection to low side of lamp. Connect to lamp terminal with longer lead length. Do not
LAMP HI High voltage connection to high side of lamp. Connect to lamp terminal with shortest lead length. Do not
Input voltage. (+4.5 to +7VDC)
the lamp. A floating input is sensed as a logical low and will disable inverter operation. If not used,
connect SLEEP through a 33kΩ resistor to V
linearly with input voltage. 2.5V gives maximum brightness.
Reference Voltage Output. 2.5V @ 500µA max. For use with external dimming circuit.
connect to ground.
connect to ground.
Not Recommended for New Designs
FUNCTIONAL PIN DESCRIPTION
or directly to any voltage between 2.5 and 5.5V.
IN
PATENT PENDING
LXM1597-01
MECHANICAL OUTLINE
.40
(10.16)
1-1
.72
(18.29)
1-8
Connector CN-1
.160 (4.06)
0.125 (3.18) Diameter Hole, 2 places
4.79 (121.6)
3.88 (98.55)
No other holes on board.
.400 (10.16)
2-2
2-1
Connector CN-2
Warning!!
High Voltage
.315 Max. (8)
.031 (0.8)
All dimensions in inches (mm)
Present
Connectors: Recommended Mate:
CN-1 = MOLEX 53261-0890 Pins: 50079-8100*, Housing: 51021-0800
* Loose (-8000, Chain) Recommended #26 AWG wiring
CN-2 = JST SM02(8.0) B-BHS-TB Pins: 5BH-001T-P0.5, Housing: BHR-03VS-1
Note: All samples are equipped with connector mates and cable.
Copyright © 1998
Rev. 0.6a 10/00
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LXM1597-01
PRODUCT DATABOOK 1996/1997
5V CCFL INVERTER MODULES
Not Recommended for New Designs
CONNECTION DIAGRAM
CMOS or TTL gate
From Power
Management
Logic
100k
51k
SLEEP
V
R
1
R
2
REF
BRITE
AGND
V
IN
LXM1597-01
GND
LAMP HI
LAMP LO
FIGURE 1 — Recommended Connection Diagram
EFFICIENCY MEASUREMENT SETUP
INTRODUCTION
The best method for evaluating high voltage, high frequency
inverters is by directly measuring light output versus power
input. This method is highly recommended when evaluating
inverter modules.
The following sections outline the recommended method
for testing these modules.
EQUIPMENT REQUIRED
1) Two DVM's with 0.1% or better accuracy.
2) A lab power supply. (0 - 20V, 0 - 2A)
3) The target notebook or LCD panel.
4) A Tektronix J1803 Luminance Head.
5) A Tektronix J17 Luminance Color Photometer.
6) A non-contact infrared temperature sensor
(i.e. Fluke 80T-IR) with a mV meter.
MEASUREMENT SETUP
Figure 2 shows the connection diagram for light output measurements. The photometer luminance head (J1803) is positioned directly in the center of the LCD screen. For best results open an application such as the Paintbrush program and
choose the maximized view so that the entire screen is "white".
After application of the power to the CCFL wait at least 30
minutes to allow for the lamp and light output to stabilize. At
V
V
BRITE
REF
Longest Lead
CFL
TUBE
Lamp Current (%) = x 100
R1= 100k typical, 5k minimum
= Value optional to determine lowest
R
2
brightness setting
= 0.5 R1 minimum
R
2
the end of the 30 minute period read the light output in cd/m
(1 cd/m2 = 1 Nit), as well as input voltage and current. Typical
applications require about 70 to 100 Nits out of the screen.
With the temperature probe record the temperature rises of
critical components such as the high voltage transformer and
the inductor.
The light output efficiency of the module can be calculated
by the following equation:
Light Output (in Nits)
Eff = =
V
IN (DC)
*
I
IN (DC)
Nits
Watt
For competitive evaluation with another module from Linfinity
or another manufacturer repeat the above steps for the second
module.
After taking the data on the second module, compare the
temperature rises on the transformer and inductors. The main
figure of merit comparison is done between the two Eff numbers as follows:
Percent More Efficient = * 100
Eff1 - Eff
Eff
2
2
The result of the above shows how much more efficient module #1 is than module #2.
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Copyright © 1998
Rev. 0.6a 10/00
Page 5
PRODUCT DATABOOK 1996/1997
5V CCFL INVERTER MODULES
Not Recommended for New Designs
EFFICIENCY MEASUREMENT SETUP (continued)
PATENT PENDING
LXM1597-01
DC
Power Supply
Amp Meter
Sleep Control = Logic "1"
Dimming
Control
DC
Volt Meter
Module
Inverter
CCFL
DC
P
= V
IN
DC * IDC
J1803
Luminance
Head
FIGURE 2 — Light Output Measurement Setup
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.
J17
Photometer
Copyright © 1998
Rev. 0.6a 10/00
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