EDNE February 2013 - (Page 38)

By Patr ick Ca r n e r • T e x a s I n s t r u m e n ts Add LED intelligence to improve light quality, efficiency, and cost Moving to digital control lets OEMs deploy a single controller to drive a large portfolio of end products, opening up design flexibility and bringing new levels of intelligence and differentiation to lighting installations. A s the lighting industry makes the transition to LED technology, the need increases for more intelligent controllers and drivers. Efficient operation of LEDs can result in substantial savings to homes and businesses as utility costs rise. Many applications need to produce consistent light quality while supporting advanced control functionality, such as dimming, balancing, and accurate color mixing. Remote connectivity is also becoming a regular requirement for applications in which self-diagnostics can reduce maintenance expenses by limiting the need for technician service calls. Bringing intelligence into LED lighting applications may require moving from fixed-function LED drivers to microcontroller-based, or programmable, architectures. Specialized power-electronics microcontrollers can further benefit lighting applications with the ability to control the luminaire power supply, in addition to the lighting control and communications, efficiently and cost-effectively. Moving to digital control opens up flexibility and can bring new levels of intelligence and differentiation to lighting products. Enabling intelligent platforms The lighting industry has been rapidly evolving to capitalize on the many benefits of LED technology (see sidebar, “Benefits of LEDs”). LED lighting applications, however, vary widely in the capabilities they need to support. Residential applications include light-bulb replacement, accent lighting, and small outdoor lighting. In general, only a few LEDs need to be lit, usually in one or two strings. Given the low-cost pressures of this market, advanced controls are generally not common. Commercial applications include fluorescent ballasts, light-bulb replacement, and accent lighting. Only a few LEDs need to be lit, usually in one or two strings. Though concerned about cost, this market is also highly energy conscious. Higher-end applications will require remote connectivity and some controller intelligence. Entertainment applications include high-end display and mood lighting. Full light-intensity control and consistent color quality are essential, as are remote connectivity and support for industry-standard protocols such as DALI (the 38 EDN EUROPE | February 2013 Digital Addressable Lighting Interface) and DMX512. Outdoor and infrastructure applications include street lighting and lighting for factories and large office buildings. Equipment typically has a high number of LEDs and must support many strings; high-brightness LEDs are common, as well. These applications require remote connectivity and a high level of controller intelligence. The simplest LED-based lighting systems use an LED driver, typically a fixed-function device that provides a straightforward and low-cost control method. In general, they offer good power efficiency and do not require software programming. At worst, developers have to make several calculations when selecting a driver or determining which configuration values to use for board-level components. While straightforward to use, many LED drivers lack sufficient flexibility for more advanced systems. Supporting multiple LED types or string configurations within a given application may call for a different solution. In fact, any change in the system, such as in the number of LEDs in a string or the number of strings in an installation, may result in a need to change the driver. Thus, most of the lighting products an OEM offers will likely require a unique analog driver. For a large portfolio of products, this requirement can increase the number of items an OEM or supplier must stock in inventory, possibly leading to lower economies of scale and higher equipment cost. An intelligent controller, on the other hand, lets developers create more flexible lighting systems. In a microcontroller- AC MAINS AC RECTIFIER PFC STAGE DC/DC STAGE .... LED STRINGS CONTROL STAGES � Figure 1 A smart LED-based lighting system has three primary stages—power conversion, LED control, and communications—all requiring intelligent control. With a digital approach to power, controllers can be combined on a single microcontroller to reduce system complexity and cost. COMMS www.edn-europe.com http://www.edn-europe.com

Table of Contents for the Digital Edition of EDNE February 2013

RS Components
Agilent Technologies
Maxim Integrated
Signal Integrity
Mesago SMT 2013
Test & Measurement World
Rohde & Schwarz
Mesago PCIM 2013
Mechatronics in Design
Hot technologies: trends to watch in 2013
Hot 100 products of 2012
Add LED intelligence to improve light quality, efficiency, and cost
Design Ideas
Product roundup
Tales from the Cube

EDNE February 2013