LXM1641-02 View Datasheet(PDF) - Microsemi Corporation
Part Name
Description
Manufacturer
LXM1641-02 Datasheet PDF : 11 Pages
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RangeMAXTM
PRODUCT DATABOOK 1996/1997
LXM1641-01/-02/-03
DIGITAL DIMMING QUAD LAMP CCFL INVERTER MODULE
HOW RANGEMAX WORKS
LAMP VOLTAGE & LAMP CURRENT — Burst Mode Operation
(770VRMS)
(7.6mARMS)
(760VRMS)
(6.7mARMS)
FIGURE 6 — 50% Burst Duty Cycle
FIGURE 7 — 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
full brightness.
As can be seen in Trace 4 of Figure 8, careful design
consideration was given to controlling lamp start voltage
to softly start current flow. This eliminates current over-
shoot that can result in premature cathode wear and re-
duce lamp life.
(760VRMS)
(6.7mARMS)
FIGURE 8 — 2% Burst Duty Cycle (Expanded Time Base)
High Voltage
VBRITE
Comparator
Transformer
VHI1
0-2.5V
DC
Ramp
Transformer
Driver
Ramp
Gen.
VSENSE
VSYNC
ISENSE
VLO
FIGURE 9 — RangeMAX Block Diagram
Copyright © 1999
Rev 0.9 12/03
9
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