MICROSEMI LXM1597-01

P
A T E N T
P
LIN D O C #: 1597
E N D I N G
LXM1597-01
5V
T
H E
I
N F I N I T E
P
O W E R
O F
I
CCFL
I
N V E R T E R
DESCRIPTION
K E Y F E AT U R E S
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.
IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.
PRODUCT HIGHLIGHT
BA C K L I G H T I N V E R T E R L I G H T O U T P U T E F F I C I E N C Y C O M P A R I S O N
■ 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
50
45
■ Narrow, Low-Profile Standard Modules Fit
Into Most LCD Enclosures
40
Eff (Nits / Watts)
O D U L E S
Not recommended for New Designs
N N O VA T I O N
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 pending Current Synchronous, Zero Voltage
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
three tasks consisting of line voltage regu-
M
■ Single Sided PCB Saves Expensive High
Voltage Insulating Tapes
35
30
25
20
15
10
5
Linfinity
0
Computer 1
Stock
Computer 2
Computer 3
MODULE ORDER INFO
5V I N P U T
LXM1597-01
Copyright © 1998
Rev. 0.6a 10/00
LINFINITY MICROELECTRONICS INC.
11861 W ESTERN A VENUE, G ARDEN G ROVE, CA. 92841, 714-898-8121, F AX: 714-893-2570
1
P AT E N T P E N D I N G
PRODUCT DATABOOK 1996/1997
LXM1597-01
5V
CCFL
I
N V E R T E R
M
O D U L E S
Not Recommended for New Designs
A B S O L U T E M A X I M U M R AT I N G S
(Note 1)
Input Supply Voltage (VIN) ............................................................................................................................................................................... -0.3V to 7.0V
Output Voltage, no load ........................................................................................................................................................ Internally Limited to 1900VRMS
Output Current ......................................................................................................................................................................... 8.0mARMS (Internally Limited)
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.
R E C O M M E N D E D O P E R A T I N G C O N D I T I O N S (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
Output Power
Brightness Control Input Voltage Range
Lamp Operating Voltage
Lamp Current - Full Brightness
Operating Ambient Temperature Range
VIN
PO
VBRITE
VLAMP
IOLAMP
TA
Recommended Operating Conditions
Min.
R.C.
Max.
4.5
0.8
240
5
2.5
Units
7
4.0
2.5
650
7
60
500
5
0
V
W
V
VRMS
mA RMS
°C
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
Min.
LXM1597
Typ.
Max.
Units
Output Pin Characteristics
Full Bright Lamp Current
Minimum Lamp Current
Lamp Start Voltage
Operating Frequency
IL (MAX)
IL (MIN)
VLS
fO
VBRITE = 2.5 V DC, SLEEP = Logic High
VBRITE = 0.8 V DC, SLEEP = Logic High
0°C < TA < 60°C
VBRITE = 2.5VDC, SLEEP = Logic High, VIN = 5V
6.2
6.6
2.6
7.0
mA
mA RMS
VRMS
KHz
-1000
2.6
nADC
VDC
VDC
50
5.5
0.8
100
VDC
VDC
µADC
2.50
2.60
VDC
µADC
3
90
10
µADC
%
1300
50
Brightness Control
Input Current
Input Voltage for Max. Lamp Current
Input Voltage for 50% Lamp Current
IBRITE
VC
VC
VBRITE = 0V DC
IO (LAMP) = 100%
IO (LAMP) = 50%
2.4
-200
2.5
1.25
SLEEP Input
Input Logic 1
Input Logc 0
Input Current
VIH
VIL
IIN
2.2
0
VSLEEP = 0 - 5VDC
Voltage Reference
Output Voltage
Output Current
V REF
IREF
0 < IREF < 500µA
2.40
500
Power Characteristics
Sleep Current
Electrical Efficiency (calculated values)
2
IIN (MIN)
η
VIN = 5VDC , SLEEP = Logic 0
LXM1597, VIN = 5VDC, IO (LAMP) = 5mARMS
Copyright © 1998
Rev. 0.6a 10/00
PRODUCT DATABOOK 1996/1997
P AT E N T P E N D I N G
LXM1597-01
5V
CCFL
I
N V E R T E R
M
O D U L E S
Not Recommended for New Designs
FUNCTIONAL PIN DESCRIPTION
Conn.
CN1
Pin
Description
CN1-1
CN1-2
VIN
Input voltage. (+4.5 to +7VDC)
CN1-3
CN1-4
GND
Power supply return.
CN1-5
SLEEP
Logical high on this pin enables inverter operation. Logical low removes power from the module and
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 VIN or directly to any voltage between 2.5 and 5.5V.
CN1-6
BRITE
Brightness control input. Apply 0.8 to 2.5 volts DC to control lamp brightness. Lamp current varies
linearly with input voltage. 2.5V gives maximum brightness.
CN1-7
AGND
Brightness control signal return. For best results do not run 5V power supply current return through this pin.
CN1-8
VREF
Reference Voltage Output. 2.5V @ 500µA max. For use with external dimming circuit.
CN2-1
LAMP LO
High voltage connection to low side of lamp. Connect to lamp terminal with longer lead length. Do not
connect to ground.
CN2-2
LAMP HI
High voltage connection to high side of lamp. Connect to lamp terminal with shortest lead length. Do not
connect to ground.
CN2
MECHANICAL OUTLINE
.40
(10.16)
4.79 (121.6)
3.88 (98.55)
2-2
1-1
.72
(18.29)
.160 (4.06)
.400 (10.16)
2-1
1-8
Connector CN-1
0.125 (3.18) Diameter Hole, 2 places
No other holes on board.
Connector CN-2
.315 Max. (8)
Warning!!
High Voltage
Present
.031 (0.8)
All dimensions in inches (mm)
Connectors:
CN-1 = MOLEX 53261-0890
Recommended Mate:
Pins: 50079-8100*, Housing: 51021-0800
CN-2 = JST SM02(8.0) B-BHS-TB
Pins: 5BH-001T-P0.5, Housing: BHR-03VS-1
* Loose (-8000, Chain) Recommended #26 AWG wiring
Note: All samples are equipped with connector mates and cable.
Copyright © 1998
Rev. 0.6a 10/00
3
P AT E N T P E N D I N G
PRODUCT DATABOOK 1996/1997
LXM1597-01
5V
CCFL
I
N V E R T E R
M
O D U L E S
Not Recommended for New Designs
CONNECTION DIAGRAM
CMOS or TTL gate
From Power
Management
Logic
VIN
SLEEP
VREF
R1
100k
BRITE
Lamp Current (%) =
LAMP HI
LXM1597-01
R2
51k
AGND
CFL
TUBE
LAMP LO
VBRITE
x 100
VREF
R1 = 100k typical, 5k minimum
R2 = Value optional to determine lowest
brightness setting
R2 = 0.5 R1 minimum
GND
Longest Lead
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)
2)
3)
4)
5)
6)
Two DVM's with 0.1% or better accuracy.
A lab power supply. (0 - 20V, 0 - 2A)
The target notebook or LCD panel.
A Tektronix J1803 Luminance Head.
A Tektronix J17 Luminance Color Photometer.
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
4
the end of the 30 minute period read the light output in cd/m 2
(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:
Eff =
Light Output (in Nits)
Nits
=
VIN (DC) * IIN (DC)
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 =
Eff1 - Eff 2
Eff 2
* 100
The result of the above shows how much more efficient module #1 is than module #2.
Copyright © 1998
Rev. 0.6a 10/00
PRODUCT DATABOOK 1996/1997
P AT E N T P E N D I N G
LXM1597-01
5V
CCFL
I
N V E R T E R
M
O D U L E S
Not Recommended for New Designs
EFFICIENCY MEASUREMENT SETUP
DC
Power Supply
DC
Amp Meter
(continued)
DC
Volt Meter
PIN = VDC * IDC
Dimming
Control
Inverter
Module
Sleep Control = Logic "1"
CCFL
J1803
Luminance
Head
J17
Photometer
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.
Copyright © 1998
Rev. 0.6a 10/00
5