As LED light quality and performance continue to improve, solid-state lighting (SSL) solutions are expanding into large general lighting markets, such as household downlighting, and thereby creating new opportunities for lighting designers, the companies they represent, and even some solid-state-savvy general lighting contractors.
Although it is likely that SSL will dominate general lighting applications in the not-too-distant future, replacing incumbent technologies, including incandescent or halogen lamps in downlights, and fending off rival technologies such as compact fluorescents, demands very high-quality white light production and the ability to deliver a desirable luminous flux.
Figure 1: LMR4-1000 package drawing.
Recently, using what it calls TrueWhite Technology, Cree has been able to take advantage of light's additive color properties to blend light from unsaturated yellow and saturated red LEDs, thereby producing warm white (2,700 K) light competitive in color temperature with incandescents.
One of the most recent products to use TrueWhite Technology is Cree's LMR4-1000 modules, which integrate thermal management, optics and LED driver electronics. These new, high-output LED modules are able to deliver 700-1,000 lumens with a color-rendering index (CRI) of 90 or above. The LMR4-1000 module is a viable replacement for 100-W incandescent fixtures because of performance in terms of light output and color rendering.
The LMR4-1000 is housed in a durable machined aluminum case that includes an integrated thermal-management system, making it a good potential candidate for downlighting applications.
According to Cree, the LMR4-1000 modules offer four color options, including 2,700 K, 3,000 K, 3,500 K, and 4,000 K correlated color temperatures (CCT), matching the CCT for incandescent light bulbs with the first two options and reaching a CCT similar to studio lamps with the latter options. These modules require a power input of 120 V/60 Hz or 230 V/50 Hz. The LMR4-1000 module supports dimming to five percent and has an estimated usable life of at least 35,000 hours.
The Cree LMR2 module is similar in terms of light quality, efficiency and purpose to the LMR4-1000 module. The LMR2 produces a nominal 650 lumens with a greater-than 90 CRI. It also includes thermal management, driver electronics and optics, but aims to replace lower-wattage incandescent or halogen fixtures.
Heat can have a significant effect on LED performance and color quality, and both the LMR4 and LMR2 go a long way to ensure that heat is being removed from the module electronics as quickly as possible. Ultimately, a completed design using one of these modules should not exceed 70 degrees Celsius at thermal equilibrium.
Cree Lighting has also developed the CR6, a downlighting solution that features capabilities similar to both the LMR4 and LMR2 LED modules. The CR6 produces 525 lumens with a CRI of 90 and has an estimated useful life of at least 50,000 hours. According to published reports, Cree Lighting had shipped significant numbers of the CR6, indicating some market demand.
A systems approach
Simplifying the design process for luminaire manufacturers requires an integrated approach for SSL systems. The ideal systems-design approach should provide manufacturers of lighting fixtures with a plug-and-play solution, including all the components required to convert from incandescent or fluorescent lighting to SSL designs. In addition to the components and design methodology, a complete systems approach should include a toolbox to allow lighting fixture suppliers of any size to easily design the latest, high-efficiency solid-state lighting fixtures with confidence and the ability to bridge the technology gap.
The TE Connectivity Nevalo system combines the many new components and disciplines of SSL systems into one simple, coherent solution that provides application flexibility. The Nevalo system includes:
- more than 60 LED Light Modules (LLM) options, ranging from 300 to 3,400 lumens, in form factors for popular lighting applications
- optics in total internal reflection and reflector styles
- drivers with constant current output, dimming-control capabilities and temperature monitoring
- a new ribbon-based, four-wire configuration wiring system that is physically keyed and color coded for polarity, accurate power connections and ease of manufacturing
Other components included in the system are heat sinks matched to the LLMs to help provide appropriate thermal management and life-expectancy and circuit-protection devices.
Figure 2: Components of TE’s Nevalo system.
Additional design and budgeting tools are incorporated into the Nevalo SSL system to help lighting manufacturers bring products to market faster while gaining cost savings. These tools include a thermal test instrument to help designers instantly test a system’s thermal performance and an SSL system budget calculator to help mix and match Nevalo drivers and LLMs. The NEVALO product configurator – a Web-based tool that aids designers in specifying a system and producing a bill of materials and a drawing – is also included in the package with a full system and cable assembly configurator to facilitate rapid system design.
To assist in lighting fixture designs, Nevalo also offers product development kits for down lights, wall sconces and track lights.