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.
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-
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.
Table of Contents for the Digital Edition of EDNE February 2013
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
Tales from the Cube
EDNE February 2013