LXM1598-01 Ver la hoja de datos (PDF) - Microsemi Corporation
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LXM1598-01 Datasheet PDF : 5 Pages
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P ATENT P ENDING
LXM1598-01
PRODUCT DATABOOK 1996/1997
12V CCFL INVERTER MODULES
Not Recommended for New Designs
100K
VCC
ON /
OFF
CONNECTION DIAGRAM
12VDC
13k
12VDC
VREF
VIN
BRITE
LAMP HI
AGND LXM1598
SLEEP
GND
LAMP LO
CCFL
TUBE
CMOS PWM
LOGIC SIGNAL
ON/OFF
CMOS LOGIC
BRITE
VIN
LAMP HI
LXM1598
SLEEP
LAMP LO
GND
PWM
Period
CMOS
FIGURE 1 — Potentiometere Brightness Control
PULSE
WIDTH
10µsec £ Period £ 100µsec
0 £ Pulse Width £ Period
FIGURE 2 — PWM Brightness Control
CCFL
TUBE
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 mea-
surements. The photometer luminance head (J1803) is posi-
tioned directly in the center of the LCD screen. For best re-
sults 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
the end of the 30 minute period read the light output in cd/m2
(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
V * I IN (DC) IN (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 num-
bers as follows:
Eff - Eff
Percent More Efficient =
1
Eff
2 * 100
2
The result of the above shows how much more efficient mod-
ule #1 is than module #2.
4
Copyright © 1998
Rev. 0.8a 10/00
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