FAN7171_F085 Datasheet, PDF (11/12 Pages) Fairchild Semiconductor – New Products, Tips and Tools for Power and Mobile Applications

ENGINEERING CONNECTIONS
Advances in LED and LED Driver Technology Pave the Way for Significant
Reductions in Global Power Usage and Cleaner Environment
The following article is a condensed version of Fairchild’s backgrounder on solutions to LED driver challenges.
The global demand for highly efficient LED products has
grown dramatically over the past 10 years, to the extent
that today’s products are rapidly encroaching on the $100
billion fluorescent light market which has flourished over
the past 130 years⁽¹⁾. Recent improvements in this 40-year
technology have resulted in “clean,” reliable and highly
efficient products which are already dominating in many
rapidly growing applications. LEDs are now the preferred
lighting source for mobile phones, full-motion signs,
traffic signals, automotive dashboards, digital
cameras, backlighting units for displays in notebook
computers, desktop monitors, flat-panel televisions, and
stadium signage.
100
10
1
0.1
0.01
0.001
Low Power Designs (<20W), include applications such as
light strips (1.5-5.0W), R-Lamps (5-10W), bulbs (3-20W)
and down lights (10-20W). The specific implementation
challenges with these applications include: (1) small lamp
size which limits component selection to the smallest
available packages, (2) small design volume, which requires
the use of low profile components and (3) cost.
Mid-Power Designs (20-50W), include applications in
the range of 20-50W, such as down lights, and L-lights.
The designer’s challenges with these applications include:
(1) limited board space, (2) available topologies that are
inherently low-efficiency, (3) need for high reliability
components and (4) power factor correction (PFC)
is required, which then increases component count.
Fairchild’s solutions for mid-power designs address these
challenges by utilizing a single-stage PFC flyback topology.
High-Power Designs (50-400W), include applications in
the range of 50-400W such as flat lights, street, stadium,
stage lighting, wall washing and signage. The designer’s
challenges with these applications include: (1) high
component count, (2) cost, (3) low overall system efficiency
and (4) increased complexity. Fairchild offers two highly
integrated high-power solutions: two-stage PFC flyback
and Quasi-Resonant (QR) flyback topology and the two-
stage PFC flyback and LLC half-bridge topology.
0.0001
1970
1975
1980
1985
1990
1995
2000
Year
The light output of LEDs has essentially doubled every 36 months since 1960.
Design Challenges for LEDs and LED Drivers
As LED capabilities improved, so too did the importance
of driver technology. Performance criteria such as LED
color temperature and shifting, efficacy and flickering,
and overall operating efficiency all became associated with
the LED driver. Legacy LED driver topologies that had
used older solid state designs and voltage regulators cannot
support new LED design performance targets. Continuous
advancements in LED performance have the effect of
requiring new topologies and more LED driver choices for
specific output power ranges and applications.
Applications and Design Support
Fairchild’s constantly expanding product portfolio,
combined with manufacturing process enhancements,
innovative topologies and our deep systems expertise
allow circuit designers to develop the most advanced
solution to their present and future needs.
Learn more about Fairchild’s total LED solutions.
(1) CFL Market Profile, March 2009, U.S. Department of Energy