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Building Blocks

Issue 54 Apr / May 2010

In the run up to Light + Building, Dr Geoff Archenhold is excited to see some of the latest developments in LED technology

The main companies within the lighting industry are rapidly aligning their long term development strategies to LEDs and this month’s Light + Building exhibition will see a positive explosion of new LED lighting fixtures from MR16s and street lights through to fluorescent tube replacements and improved LED downlights.

As I will discuss later, even global conglomerates that are new to the lighting sector such as Mitsubishi Chemicals, are now entering the European market tempted by the significant growth prospects of the energy efficient lighting market within Europe. Such immense activities of both traditional lighting companies and serious new entrants will inevitably lead to high quality LED lighting systems whilst enabling customers with choice. Such choice will lead to a highly competitive LED lighting market that will in-turn reduce costs and increase market adoption rates faster than expected.

The rate of LED emitter improvement still continues with both Cree and Bridgelux announcing large increases in lumens per watt performance of individual and LED arrays.

This month’s article will also cover how further advantages in cost effective electronics is enabling high efficiency, long-life LED drivers to be constructed utilising Digital Signal Processing (DSP) techniques.

LED technology update – Quarter 1 - 2010

Bridgelux Inc., unveiled in February 2010 three new LED array product families that deliver high-quality, energy-efficient light sources. These new products are designed to replace incandescent, halogen, high intensity discharge (HID) and compact fluorescent lighting. The low power consumption, long lifetime, and high quality light of the Bridgelux LED Arrays deliver ideal options for indoor and outdoor applications ranging from retrofit light bulbs to street and wide area lighting.
The Bridgelux LED Array product portfolio now features light output performance that ranges from 240 to 4500 operational or ‘hot’ lumens (lumens under normal operating conditions).

• The Bridgelux ES Array Series enables lamp and luminaire manufacturers to cost-effectively meet rapidly increasing global regulatory standards for general lighting such as Energy Star and Title 24 in the United States and Part L in the United Kingdom. The series delivers between 400 and 2000 ‘hot’ lumens in a compact high flux density light source, enabling the replacement of incandescent, halogen and fluorescent conventional light sources. These new arrays are 30-60% more energy-efficient than previous product generations while dramatically reducing the price per lumen.

• The Bridgelux RS Array Series delivers high light output for applications including retail, street, wide area, high bay, and commercial lighting, replacing conventional light sources such as 50-70 watt metal halide (HID) and high wattage compact fluorescent (CFL) lamps. These arrays produce between 3100 and 4500 ‘hot’ lumens, enabling clean and uniform lighting effects without pixilation and excellent beam control for precision lighting. In retail lighting installations, these arrays have delivered a return on investment of less than two years while delivering the high quality of light proven to positively influence product turnover and customer experience in this environment.

• The Bridgelux LS Array Series is a new set of miniaturised LED arrays that enable both diffuse and directional light sources for applications including landscape lighting, home luminaires, white goods and retrofit light bulbs. Delivering between 240 and 360 lumens, these products are ideal replacement options for low wattage halogen, incandescent and CFL lamps.

Cree have again raised the bar in terms of lumens and lumen per watt from a single LED die with the launch of the XLamp XP-G LED in Warm White (CCT 3000K) as shown in figure 2. The typical CRI is 80 for Warm White and 75 for Neutral White versions. The latest XP-G devices are capable of being driven at 1.5A and have a thermal resistance of just 6°C/W.

The XP-G enables a level of efficacy in indoor lighting applications never before possible whilst opening up the possibility of reducing LED system costs. Figure 3 highlights the impressive performance of the XP-G with both efficiency and luminuous flux plotted against LED current for both the Cool white and Warm White versions of the XP-G LEDs.

As figure 3 shows, the XP-G can deliver 100 lumens and 100 lumens per watt in warm white (3000K) light meaning that with quality system design the XLamp XP-G enables systems that could deliver 60 or even 70 lumens per watt of “wall-plug” efficiency – taking all the electrical, thermal and optical loss into account. State of-the-art warm white LED systems today are around 40 to 50 lumens per watt, so this represents a significant breakthrough in delivered efficacy.

Another key feature is that the XLamp XP-G can be driven to high drive current and still maintain good efficacy. For example the 3000K XP-G will deliver an impressive 319 lumens at 1.4A providing an overall efficacy of 64.6 lumens per watt or 250 lumens at 1A and 73.5 lumens per watt. This performance enables LED systems to use much fewer LEDs and maintain the same efficacy level. Generally, one XP-G LED can replace three to four high power LEDs with no drop in light output or increase in power level. Using fewer LEDs means fewer optics and a smaller overall system, and ultimately a potential reduction in system cost.

Seoul Semiconductor has also increased the performance of its Acriche A4 (see figure 4) AC driven LED emitter to 100 lumens per watt for its cool white version and 90 lumens per watt for its Warm White product.
Interestingly Verbatim, a Mitsubishi Chemical company, will announce its entry into the European LED and OLED lighting markets at Light + Building 2010. Verbatim is a global consumer brand best known for Optical, External Hard Drives and Flash Memory data storage and will be used by Mitsubishi Chemical to introduce its entry into the lighting market at Light + Building. Verbatim’s forthcoming LED lighting products include the company’s unique approach to the design of high colour rendering index LED and colour tunable lighting systems available later this year.  They will also demonstrate the world’s first dimmable/tone adjustable OLED prototype that has been developed through the recently announced Mitsubishi Chemical Corporation and Pioneer Corporation OLED alliance.

Further details on Verbatim‘s exciting new LED and OLED products will be covered in the next LED article along with the details of my interview with Mitsubishi Chemical’s CEO and President, Dr. Kobayashi.  

New DSP LED driver platforms
The latest LED drivers are moving towards the adoption of Digital Signal Processing to improve LED driver performance and lifetimes. Two LED driver companies have adopted DSP technology within new driver products including DLED Illumination Technologies of Israel and IST from the UK.

DLED launched the DR-SD6 and DR-SD12 Din rail DC/DC DMX driver which utilises up to 6 and 12 channels respectively in multiple current source configurations. The DR-SD6 driver caters for up to 172W (6x12x3W LEDs) and the DR-SD12 caters for up to 435W (12x12x3W LEDs). Both drivers are capable of high efficiency DC/DC conversion up to 95% and the system is driven in a standard DC mode to reduce system flicker.

IST will also be announcing at Light + Building the launch of its new eco-DSP LED driver technology platform based upon its patented Pulse Amplitude Modulation technique. The first two drivers to be launched include the iDrive-Quad a 120W four channel DMX/RDM driver and a single channel DALI and 1-10V 45W LED driver for the LED downlighter market. The eco-DSP platform offer DC/DC efficiencies up to 98% (see figure 5) and both LED drivers incorporate new green driver technology to provide AC/DC efficiency in excess of 90% along with a PFC of 0.95.
The new eco-DSP platform is easily configurable into various driver powers and is capable of working with various LED forward currents and voltages without compromising overall driver efficiency as shown by figure 5. A patented in-built power monitor enables each eco-DSP driver to operate safely at maximum power across all system channels. For example, the 120W iDrive-QUAD has 4-channels capable of driving up to a maximum of 50V and 1A per channel however the eco-DSP system continuously monitors the power used across each of the 4 channels and directs any spare power to those channels that request more power. The patented power monitoring technique enables RGB or RGBA systems to operate at higher forward currents than normally found with standard LED drivers as shown below:      

Standard 120W 4-Channel driver = 30W per channel

Therefore, if an LED array has a forward voltage of 38V per channel the maximum current per channel would be 30/38A or 789mA.
However, with the eco-DSP system each channel can be set to a maximum of 1000mA per channel and depending on the dimming level for each channel the maximum current will be achieved enabling a much brighter light output from the LED system to be achieved. Similarly the same eco-DSP system can be used on a 350mA system to deliver a 700mA output when being used in colour changing scenes.

IST claim that the new eco-DSP technology not only saves energy but also extends driver lifetimes as the system does not require electrolytic capacitors on the LED channel outputs and is more efficient than majority of LED drivers so offer a significantly smaller driver footprint. For example, the AC mains powered 120W 4-channel LED driver has dimensions of only 210mm x 90mm x 45mm.
In the next edition of the mondo*arc I will cover all the latest LED news and discover the vast array of LED products being launched at the Light + Building exhibition in Frankfurt. If you would like me to visit your stand at L+B please email me at


Figure 1: The Bridgelux RS and LS high power LED arrays

Related Articles

  • Figure 2: The new 3000K XP-G LED from Cree

  • Figure 3: The lumen and lumen per watt performance of the Cree XP-G

  • Figure 4: The new Acriche 100lm/W AC LED

  • Figure 5: The eco-DSP DC/DC LED driver channel efficiency verses LED forward voltage


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