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Design Article

MCU-based LED drivers inspire designs

Alex Zaretsky, Renesas

12/3/2012 11:56 AM EST

Outlook
It is being observed that the market is moving towards LED drivers operating directly from the mains. The RL78/I1A MCU with its on-chip PFC controller would have a definite advantage in terms of system costs and space for lighting ballasts above the 25W rating. On the output side, though, the higher voltage levels required will depend very much upon what the designer aims to achieve with the application. Here the customers will have to make a compromise between targeted application goals and the driver output specifications at hand. However, with the flexibility of available and forthcoming lighting solutions, Renesas lighting products would be able to cover most of the future application requirements.

One potential factor for efficiency enhancement is to consider special design techniques and features for LED drivers coupled with software – in other words, bringing more intelligence into the drivers. Such intelligent drivers could take over communication tasks, manage sensors, steer dimming, handle enhanced controls etc. Renesas considers the development of such intelligent drivers as very important.

In the mid-term, such intelligent drivers would even be instrumental in improving the brightness and the life cycle of the OLEDs. Intensive work is ongoing at Renesas to further improve the degree of degradation compensation of the LED/OLED lumen output over life cycle, the PWM control (finer dimming), and more precise color mixing suitable for dedicated applications.

All these factors are important in public and domestic lighting applications where not only longevity, brightness and dimming functions play a role but also subjective comfort perception of “color temperature” of the light by people is equally important. Thus besides considering costs and power efficiency issues and the LED driver design, engineers will also have to take into account the target application - such as domestic, production floor, public places, or street-lighting - for which the potential LED light source is required.

Renesas engineers are working incessantly on innovative processes to optimize internal architecture, enabling the design of lighting ballast systems with enhanced intelligence and higher functional integration density. The overall goal is to have lighting ballast electronic components with the best technical, cost efficient, and environmental compromise.

References:
1. RL78/I1A User’s Manual - Hardware
2. RL78/I1A In-Circuit Emulator (IECUBE: QB-RL78I1A)
3. RL78/I1A E1 Emulator
4. RL78/I1A Evaluation board (QB-78F7032-TB)
5. Link: http://www.renesas.com/products/mpumcu/ri78/rl78i1x/rl78i1a/index.jsp

About the author:
Alex Zaretsky spent 7 years at Embedded Systems, working on the development of a variety of medical and industrial applications. In 2007 he joined NEC Electronics (now Renesas Electronics) and worked as a Senior Applications Engineer for lighting. In 2009, he was promoted to Marketing. Since then, he runs all major lighting segment activities at Renesas Electronics Europe. This also includes defining the roadmap for Renesas dedicated lighting products and the strategy for the key lighting accounts. Mr. Zaretsky has authored more than 20 marketing and technical publications and is an active member of the DALI consortium. Furthermore, he works closely with other known lighting industry organizations such as the LIA.

Courtesy of EETimes Europe

See related links:
Power and controlling high brightness LEDs

LEDs tailor automotive lighting, improve safety

LED drivers provide control, circuit-protection design options

Controlling multiple LED strings with C2000 MCUs

LED lighting drives demand for phosphors

Developing smart LED-based lighting systems


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anne-francoise.pele

4/12/2013 8:57 AM EDT

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