Specifications

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9
With the proliferation of high-luminosity LEDs, the lighting industry
is now moving towards compact Switch Mode Power Supplies
(SMPS) to provide efficiency. ON Semiconductor power
regulators offer a simple and economical way to design power
supplies that comply with stringent energy-saving
requirements. The proprietary high-voltage technology includes
a 700V power MOSFET with a start-up current source, all
directly connected to a bulk capacitor.
To quote Pirelli’s tyre
advertisment,
‘Power is nothing
without control’.
Equally, the same
analogy can be
drawn with lighting:
the end user is
unlikely to care how
many lumens of light their
luminaire radiates, compared to visible lux
or candela in the area of illumination.
Producing the required values of lux
means controlling and directing light
output and, in the same way, it means
keeping light away from other areas.
To help designers make the most of
their LUXEON Rebel LEDs, Carclo has
developed a range of optimised 20mm-
diameter secondary optics. These include
optics capable of producing beam widths
between 9° and 35° Full Width Half
Maximum (FWHM), as well as an optic
capable of producing an elliptical beam
measuring 10
° by 40°, and two frosted
variants with integrated diffusers suitable
for architectural
applications.
All of these
optics boast
upwards of
85% efficiency,
allowing users to
make the most
of the LUXEON
Rebel LEDs. When
mounting secondary
optics it should be remembered that
positioning optics at the correct height
relative to the LED is critical to achieving
the best efficiency
and the correct
beam width.
The alignment of
the optic axis to the
LED chip also plays a part. If incorrectly
positioned, the output beam will become
uneven and offset. The placement
accuracy required is dependent on the
beam width of the optic. Generally the
wider the beam divergence of the optic
the more tolerant it will be of axial
displacement. As a general guide, an
accuracy of ±0.25mm is required for
optics that produce the narrowest beams.
To help users mount their optics at the
correct focus height and to align them with
the LUXEON Rebel LED chip, Carclo can
supply a general-purpose optic holder that
mounts on the PCB and locates the optics
correctly above the LUXEON Rebel.
Further details of Carclo’s optics and
holders are available from Future
Lighting Solutions.
Secondary optics harness the LUXEON Rebel
As an example, they’ve designed an isolated, universal-
input LED ballast, operating with LUXEON LEDs and
providing a wide input-voltage range from 85VAC to
265VAC. The NCP1013 low-cost, monolithic controller
minimises peripheral circuitry by integrating functions such
as start-up and current limit. A patented Dynamic Self-
Supply (DSS) function, for example, eliminates the need for
a transformer auxiliary winding by allowing the integrated
circuit to bias itself directly from a high-voltage input rail.
The board includes an input filter, a bridge rectifier,
smoothing capacitors, a power stage and a rectifier diode,
as well as bulk capacitors and line inductor in a Pi-filter
arrangement. There is a constant current drive feedback
topology for the LEDs with a constant voltage in the event
of an open circuit output.
Efficient
LED-ballast design
with
power regulators
The circuit delivers 5W of output power and can drive one or
two LEDs. The output current can be adjusted to 350mA,
750mA or 1,000mA to match with the requirements of the
LUXEON LED range. More information on low-cost 1N4007
diodes and NCP1013 monolithic controllers is available from
Future Lighting Solutions.
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When responding to
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