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Figure 3. 22W LED Driver Circuit with LF77944.
typically needs to be less than 20
percent. There are cur-rently no
standards governing flicker. Most
manufacturers and cus-tomers accept
the US ENERGY STAR recommended
spec for calculat-ing the flicker index.
It suggests a figure of 0.15 or lower
to be opti-mal since values below 0.15
are considered imperceptible. As a
con-sequence, lighting manufacturers
typically aim to achieve or improve on
this limit.
Direct AC Driver for
Superior Performance
All these problems are now being
addressed, as Fairchild, a leading
global supplier of high-performance
semiconductor solutions, recently
introduced its new FL77944 LED Direct
AC Drive family of solid-state LED
lighting solutions. The FL77944 and
the IP provided by Fairchild enable
a tunable flicker index below 0.10
while maintaining PF > 0.9 and THD
as well as analog and PWM dimming,
which is key for wirelessly connected
lighting.
•
Scaling for higher power
applications. The Fairchild FL77944
can scale upwards to suit higher
power applications well above
120W. This is simply done by wiring
products in parallel. It also reduces
the number of different ICs that
lighting manufacturers need to keep
in inventory.
•
Elimination of electrolytic
capacitors. System designs with the
FL77944 can eliminate the electrolytic
caps, transformers and inductance
coils. This reduces both the bill-of-
materials (BOM) costs and the overall
complexity compared to designs using
SMPS.
•
Reduced board space.
Locating the controller IC on the same
PCBs as the LEDs, aided by the absence
of electrolytic caps, transformers
and inductance coils enables more
< 20%. LED lighting manufacturers
can use these integrated driver circuits
to easily scale power conditions. This
will enable them to create smart
and scalable LED systems that are
smaller, have higher performance
and reliability, offer size advantages
and a lower component count as well
as longer lifetimes compared to the
traditional SMPS approach.
The FL77944 is a cost-effective
integrated circuit with everything
manufacturers need for smart
LED lighting products so they can
accelerate time-to-market and focus
on differentiating features, rather
than spending precious time cobbling
together disparate components.
The new Fairchild FL77944 DACD
solution offers:
•
Comprehensive dimming
capabilities. It enables all the dimming
capabilities required for smart lighting
products, including phase-cut dimming
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