Nov 24 2009 11:14AM | Permalink | Email this | Comments (5)

Last week a reader posted a question on the article, Power-converter IC targets dimmable LEDs, needs no optoisolator, asking, “Can anyone explain why LED lighting needs isolation from the AC line? Incandescents require no such isolation; why burden LEDs with this?” My understanding was that it was aUL rule, but before I pushed the “submit” button on my reply, I decided to ask the folks at iWatt. Here’s iWatt’s reply:

"The US Department of Energy's Energy Star program does not mandate the use of isolated or non-isolated LED drivers for offline LED lamps. The LED lamp manufacturers are free to use isolated or non-isolated LED driver designs. [However, a] heat sink is often used to take away heat from the LEDs. The heat sink is generally made of metal and i... + read more

Nov 23 2009 10:11AM | Permalink | Email this | Comments (2)

After seeing the role played by electrolytic capacitors in the lifetime of solar inverters and the importance of accurately derating them,, I asked the technical folks at AVX to talk about ceramic capacitors appropriate for another application that requires long lifetimes: LED lighting. Ron Demcko, application engineering manager at AVX, got back to me. Here’s Ron’s reply.

The perceived disparity between the life of LEDs (60,000 hours) and that of capacitors (perceived as 8000 hours) is a hot topic within the Solid State Lighting (SSL) world.

Many different types of capacitor technologies already exist that yield very reliable capacitors. Power film capacitors for example, have internal fuses with... + read more

Nov 18 2009 7:51PM | Permalink | Email this | Comments (1)

There’s an emerging market for power supplies in LED lighting and signage. IC vendors are salivating over the huge market for LED bulbs to replace incandescent and CFL bulbs, which will all need their own ac/dc power ICs. But the largest bulb replacement market of all, replacing the 60W light bulb, will have razor-thin profit margins and most likely go straight to Asian manufacturers. A more promising market for US technology companies focusing on high-power LEDs is signage, displays, and industrial lighting.

You may have seen the Mitsubishi screen at the Dallas Cowboys’ stadium which is billed as the world’s largest LED video display.

This display uses 22,000 Lambda-TDK power supplies,... + read more

Nov 16 2009 9:27PM | Permalink | Email this | Comments (9)

It turns out it’s possible to trademark a color. For example, T-Mobile owns the color magenta. Really.

Here’s an explanation:

“To clarify, companies like T-mobile can only trademark in the industry sector that they are registered in. So T-Mobile has trademarked the color magenta in telecommunications. The blog ... + read more

Nov 5 2009 10:56AM | Permalink | Email this | Comments (0)

Do you have a good topic for a technical paper for the 2010 “Designing with LEDs” Workshop to be held March 17 at the Santa Clara Convention Center? We’re looking for papers on power control, thermal management, optics, and lighting control and networking. If so, please fire off an abstract summarizing your paper in 300 words or less and send it along with author information (name, title, company, and contact information) to me at mconner@reedbusiness.com. Deadline to submit is December 4.

The LED Workshop, which is the only event of its kind to focus on the HB LED drive and control electronics as well as thermal management, will be a great place to see and discuss the latest advances in this booming technology, and to network with fellow designers and developers. For more in... + read more

Oct 22 2009 1:13PM | Permalink | Email this | Comments (5)

When I saw the headline over at Make magazine, “Eternal flame replaced by LEDs,” I thought I understood immediately what the article would be about. Some monument somewhere which previously had a natural gas flame was “lowering its carbon footprint” by switching to LEDs. Not exactly.

It seems the memorial, located in the Ukraine, was erected after WWII to commemorate the many, many who died there. Natural gas was one of the plentiful commodities under the USSR regime, and for 50 years there was no trouble getting the flame illuminated with its own natural gas line. However, when things started to fall apart in the USSR several years ago, the free natural gas stopped, and it was to... + read more

Oct 20 2009 6:42PM | Permalink | Email this | Comments (14)

Cree is inviting folks to submit their photos of lousy lighting. Each month Cree will give away 5 of Cree’s LED-based  LR6 recessed downlights to some lucky winner. Lest you think that’s not a very big give-away, look at the lights’ current price: $98 ea.

Doug Leeper mentioned a while ago that he had bought a Cree LR6 and wa... + read more

Oct 13 2009 11:09AM | Permalink | Email this | Comments (1)

Lest anyone thought the LED-lit, bubble-themed arena design of the Beijing Sports Cube was a fluke, here’s the winning design for the 2014 Winter Olympic Games in Russia. There are very few details on the design itself, other than, “…the exterior shell of the stadium involves a translucent, crystalline skin which engages with the surrounding landscape during the day, and is illuminated at night.” Sounds like the same infinitely changeable LED-based lighting approach of the Water Cube, and its 496,000 Cree XLamp LEDs in red, green and blue.

Via designboom.

 ... + read more

Sep 30 2009 10:08AM | Permalink | Email this | Comments (7)

In the rush to embrace LEDs as the Great Hope for energy-efficient lighting, it’s easy to forget that LEDs themselves are only part of the design equation: The power control electronics are vital components in ensuring both power efficiency and thermal performance for lighting.

We’re having the lunchtime panel discussion that features many of the significant players in LED power management ICs**. I’d like to lead off with some questions that will both spark a good discussion among the panelists, as well as take advantage of the wide variety of experience and design approaches represented on the panel. For example, a softball question might be, “When designing a triac-dimmable LED light, what are the most important features the driver IC should have?” Or, “Are there any gotchas in driving the LED that will affect the life of the LED or ... + read more

Sep 28 2009 11:16AM | Permalink | Email this | Comments (7)

In spite of their high lighting efficiency, the cost of high-brightness (HB) LEDs for commodity applications is not low enough yet to compete head-on with older forms of lighting such as incandescent and high-intensity discharge (HID). However, certain applications can justify paying a premium for high-efficiency, long life, ruggedness, and light-color temperature control, and these applications are the sweet spot for HB LEDs.

Here’s a good example (pictured in the brochure below): Solar-powered outdoor lighting for off-grid applications. This Solar Vision Pole’s lamp post is especially novel, because rather than use a standard rigid solar panel that requires additional bracing for wind shear (and can attract the attention of scavenging thieves), the pole itself is wrapped with a flexible solar panel that ... + read more

Sep 24 2009 6:02PM | Permalink | Email this | Comments (15)

Philips Electronics has become the first company to submit an entry for the L Prize competition, which is sponsored by the Department of Energy and seeks an LED replacement for the common 80W incandescent light bulb. In addition to bragging rights, the winner will get a significant chunk of the $10M prize fund.

Required metrics for the 60-Watt incandescent LED replacement, as laid out by DOE, include:

• Efficacy of more than 90 lumens per watt, which exceeds the efficiency of all incandescent and most compact fluorescent sources today, which range from 10 to 60 lumens per watt
• Energy consumption of less than 10 watts as compared to a 60 Watt incandescent.
• Output of more than 90

Sep 24 2009 12:09PM | Permalink | Email this | Comments (7)

We now have two OSRAM development kits to give away at the free “Designing with LEDs” workshop in Chicago on October 6. The kits aren’t just a handful of LEDs – they  include a power supply board, an ac adapter, a plastic lens, and heat-sink-mounted versions of OSRAM’s OSTAR Lighting, Observation, and Headlamp devices, which target general lighting, projection, and automotive applications.

The workshop features a keynote by LED visionary Cary Eskow, panel discussions with both LED and power IC manufacturers, technical papers, and three hands-on workshops. As you can see, it’s a lot to pack in one day. It’s free, but attendance is limited so click on over and register now.

Sep 17 2009 9:34AM | Permalink | Email this | Comments (6)

September 1^st marked the beginning of the phase-out of the incandescent bulb in European Union countries. Intrepid reporters at the British newspaper, the Telegraph, decided not to trust the packaging information on CFLs claiming the enclosed 12W CFL had the equivalent light output of a 60W incandescent. The Telegraph reported that, when measured with a hand-held light meter placed half a meter away from the test light bulb in an otherwise-darkened room, that a frosted 60W measured 101 lux, while a 11W CFL made by General Electric and handed out free to a local utility’s customers measured only 79 lux.

(... + read more

Sep 15 2009 11:40AM | Permalink | Email this | Comments (2)

[Are you interested in learning about the latest in designing with HB LEDs? Sign up now for EDN's free "Designing with LEDs Workshop", Oct. 6 in Chicago.]

Last April at Milan Design Week Philips unveiled its OLED-based Lumiblade lighting which it claimed would be the first OLED lighting to reach the mass market. The designs unveiled at Milan were mostly small, lamp-sized devices that did an excellent job of showing off OLEDs’ potential to provide diffused, wide-area lighting, as opposed to the point-source lighting you get from traditional lighting sources.

Philips has announced ... + read more

Sep 8 2009 10:42AM | Permalink | Email this | Comments (5)

Take a look at a couple of comments on the previous post regarding the efficacy of production LEDs, Real-world numbers on production HB LEDs: 32% efficiency . A reader points out that using 683lm/W (from Wikipedia) as the 100% luminous efficacy figure, (theoretical maximum lm/W), then Cree's 114lm/W works out to a luminous efficacy of 114/683=17%, which is the original figure from the first post.

Doug Leeper responds: 

(I’ve posted the comment below to save clicking back and forth.)

 “On the max 100% luminous efficiency numbers, one has to consider the spectrum…which greatly alters that number.

The luminous flux is the part of the power that is perce... + read more