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Harmonized Two-Stage LED Driver Systems

neurological problems, fatigue, headaches, etc. One may not visibly Dual-stage architecture: PFC boost followed by a constant-current
see the light source’s modulation, but its effects may be felt. IEEE- flyback or LLC converter
1789, a standard that addresses light modulation, is becoming the + Cost
dominant standard for light-modulation limitations within lighting ++ Dimming performance
products. It will be a requirement in some form over the next couple ++ Efficiency
of years. ++ Ease of regulatory compliance
Finally, no article on lighting is complete without the mention
of intelligent lighting systems. The adoption of intelligent lighting
systems has not matched the pace of SSL adoption, but there are
signs of life as the market settles on common ground.
Considering the challenges, it has become problematic to satisfy
all design and regulatory specifications with a single-stage power-
conversion architecture. Today’s hardware electronics engineers
are resolving the requirements by developing multiple-stage driver
designs. With two power-conversion stages, the design engineer can
split the performance and regulatory requirements between the two Dual-stage architecture: PFC/flyback with a constant-voltage
conversion stages and optimize accordingly. Let’s review a few output followed by a DC/DC secondary-side post regulator
common LED driver architectures for LED drivers with sub-100-W (constant current)
loads and rate them on the discussed metrics: ++ Cost
+++ Dimming performance
Single-stage architecture (PFC/flyback) ++ Efficiency
+++ Cost +++ Ease of regulatory compliance
+ Dimming performance
+ Efficiency
+ Ease of regulatory compliance

For designs with output power less than 100 W, the topology that
satisfies all requirements is the single-stage PFC/flyback followed by a

Simplified illustration of XDPL8219 + BCR601

www.eetimes.eu | NOVEMBER 2021