
D
IGITAL
D
IMMING
D
UAL
L
AMP
CCFL I
NVERTER
M
ODULE
P
R E L I M I N A R Y
D
A T A
S
H E E T
LXM1621-xx
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
Copyright 2000
Rev. 0.6 2/00
8
P
A T E N T
P
E N D I N G
RangeMAX
TM
1 0 0 0 : 1 D I M M I N G A P P L I C AT I O N
The following application defines techniques capable of deliver-
ing dimming ranges in the 250:1 and 1000:1 range. As is widely
understood, hese echniques will provide general capabilities and actual
system performance will vary with panel design, CCFTs, ambient tem-
perature and a number of other variables outside the control of the
inverter. These methods can be used in conjunction with other tech-
niques such as amp heating and matching.
FIGURE 9
— Average Lamp Current vs. V
BRITE
Voltage
(per Lamp)
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).
2) By making a resistor value change on the module. If this
option is preferrable, please contact the factory for applica-
tion 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
BRITE
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.
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.
RangeMAX
and
Direct Drive
are trademarks of Linfinity Microelectronics Inc.
RangeMAX INVERTERS
Also available in Single
Output
LXM1611-01
,
LXM1612-xx
or Quad Output
LXM1641-01
versions for
multiple lamp applications.
0V
2.5V
-100mV
7
0.7
.14
.070
V
BRT ADJ
(V)
I
O