LED-downlight reference design achieves high-performance dimming while reducing component count

February 27, 2013 // By Paul Buckley
Power Integrations has introduced an LED-downlight reference design that offers high-end dimming performance from a single-stage LED driver together with all the associated efficiency, space and cost benefits that the single-stage approach brings.

The RDR-347 12 W reference design, based on the LYT4313E, delivers a power factor greater than 0.95 and reduces total harmonic distortion (THD) to less than 10% - easily meeting EN61000-3-2C requirements. Efficiency is greater than 86% at 120 VAC – industry-leading performance for an isolated solution capable of operating with a wide range of dimmers. This performance is possible because

LYTSwitch ICs use one combined PFC and CC power conversion stage which minimizes losses and cuts component count, which in turn increases reliability and decreases cost.
TRIAC dimming is challenging, especially deep-dimming where TRIAC asymmetry between half-cycles can have a significant effect. RDR-347 shows that Power Integrations’ LYTSwitch driver IC works excellently, even at very low output currents, without any shimmer or flicker.

The design also demonstrates system start-up without noticeable hysteresis (so-called 'pop-on effect'), even in deep-dimming. The IC features a very fast start-up time (under 500 ms) even when dimmed to 10% output current, achieving the ‘instant-on' condition that many customers want, but that many designs in the market cannot provide.

More information about the RDR-347 LED-downlight reference design at