Differentiating Your LED Design - Embedded.com

Differentiating Your LED Design

As the light emitting diode (LED)market continues to grow, pressure increases for lighting manufacturersto stay ahead of the curve, especially with hundreds of new playersjumping in to take advantage of the $2 billion dollar potential.

Many have little experience with electronics, being more familiarwith standard florescent and incandescent bulbs. The literally milliondollar question for these companies becomes how to set their lightingdesign apart from all the other competitors out there.

Currently, when most lighting customers think about differentiation,they think about using color LEDs for mixing light. These RGB, RGBA,etc. applications fit an interesting niche in both architectural andstage lighting designs.

 However, a lack of imagination has gripped the market in termsof taking many of these same principles and attacking the substantiallylarger White Light market.

Most engineers are currently creating “me-too” white light designsby taking “x” number of white LEDs from a manufacturer such as Lumileds, adding up the lumenstoequal or surpass that of a fluorescent, hooking it up to a ballast, andcalling it good. This does not appear to be a recipe for long-termsuccess.

There are few technological advances that stop at the replacementlevel, and as customers gain a new perspective on the additionalfeatures of LEDs, it would be unfortunate to assume that there would beno further utilization.

This article will explore several examples of differentiating whatappears at face value to be a simple LED design. Each of these examplesdeserves far more space than can be devoted to here, but should serveas a starting point for additional creativity.

The key to this step is the addition of basic intelligence to thecircuit, generally in the form of a microcontroller. Intelligence isnecessary to take advantage of what LEDs offer as much to white lightdesigns as to color.

Tune to Temperature
The first example of a key differentiating feature is the ability totune color temperature along the black body locus. It is relativelysimple to imagine why one wants to mix color, and still there has yetto be substantial progress made towards the same principles with whitelight.

As lighting customers become more discerning, the option of anyspecific color temperature between 3000K and 6500K is appealing. Thisalso means that designers can maintain a single white light fixturedesign that avoids the need for constant revision dependent on a Correlated Color Temperature (CCT)specification.

What is interesting to note about tuning white light is that itactually is normally done through mixing color LEDs. This originallywas done with a simple RGB interface, but designers quickly noticedthat the ColorRendering Index (CRI)was extremely poor.

CRI is important in order to reproduce an item's color as it wouldbe under natural light, especially vital in such applications asdisplay lighting. A merchant doesn't want good jewelry looking bland.

To alleviate this concern, designers have tried RGBA, RGGB, andRGBW, and each configuration has their advocates. Intelligence canensure that whatever LED configuration a designer selects will have thebest possible CRI by calculating the dimming percentages required todrive the LEDs efficiently. Companies such as Future Electronics havedone excellent work in assisting designers with this often difficultprocess.

Even if a high CRI is not a top design requirement, some sort ofsimple tuning can be beneficial, this time only with two strings ofwhite LEDs, cool and warm white. This approach can provide the samenumber of lumens while also allowing the designer an easy way todifferentiate the product, especially from standard fluorescent bulbs.

Intelligence through Communication
A secondary form of intelligence and differentiation is in the form ofcommunication. Even in static white applications, the process ofretrofitting lighting fixtures in an existing infrastructure givesdesigners the unique ability to introduce networking features withoutthe need for additional wiring.

This last advantage is important, because few designers want torequire that installation, as it is quite cost prohibitive. Yet thedifferentiation potential of communication can be tremendous, as thesetup allows for dimming and color temperature control to be controlledthrough a central hub.

Power Line Communication (PLC)is a technology that takes a carrier signal and routes it throughexisting power wiring, thus saving on installation costs. In oneexample, PLC is a 2.4 kbps FSK modem which can be robust over 100mdistance, suitable for most home/office applications (Figure 1, below ).

Since PLC can be voltage agnostic, it does not require substantialboard redesigns for separate usages. It should be mentioned that PLCcan encompass far higher bandwidths as well, as it is being pushed bysome companies up to the 200 mbps level, which could be over powerlines or also over Ethernet.

Figure1: PowerLine Household Application

The use of various wireless communication technologies can alsoeliminate the need for home/office rewiring. The robustness of RFsolutions has continued to improve, to the point of eliminating theinterference from certain household objects such as the dreadedmicrowave.

Integrating wireless is less of a chore than in the past, assuppliers have introduced module solutions that utilize a simple serialinterface for communication to a main microcontroller, eliminating theneed to go through the challenge of such design steps as FCCcertification.

Wireless options are especially interesting for the entertainmentlighting market, where the light placement can then take full priorityover additional wiring concerns.

Figure2: WUSB Remote for Lighting Control

Peripheral Functionality
Even without turning to tuning or communication techniques, creativedesigners are still finding ways to make their products stand out inthe market through the last discussed differentiating feature;peripheral functionality.

As energy costs continue to rise, companies are searching foradditional ways to find value. One key regulation that has become aselling feature is the EnergyStarrequirement, and has pushed designers to search for uniquewaysto manage energy usage.

Obviously this has been a standard selling feature for LEDs ingeneral, as their efficiency can be up to four times that of standardreplacement bulbs. Adding some peripheral controls to increase thatefficiency can truly help a company stand apart. This can be donecheaply using an ambient light sensor or passive infrared sensor (PIR) (Figure 3 below )..

Figure3: PIR Occupancy Senso

The basic functionality of an ambient light sensor or PIR sensor isfairly well known, so it will not be discussed here. The point is thattracking light or occupancy can dramatically decrease total energyusage of the fixture. Below are a few examples.

The ambient light sensor can track the available light depending onthe time of day and adjust the dimming of an office lighting networkaccordingly. A PIR sensor can act as an occupancy sensor in anautomobile, cubicle, or home, and turn on/off a light depending on thefeedback. Even something as simple as the light on the front of a whitegoods appliance can utilize a simple sensor in order to only turn onwhen needed.

One final peripheral function that can be a key differentiatingfactor is the addition of capacitive control (Figure 4, below ). This refers to thereplacement of mechanical buttons or switches with a capacitive traceinterface that has advantages in aesthetic appeal and in beinghermetically sealed.

The explosion in popularity of this type of interface in the MP3 and cell phone market makesitan intriguing feature for lighting. Also, the number of capacitivesolution providers is rapidly expanding, so the ability of a designerto find the right fit for their solution has improved.

Figure4: Capacitive Lighting Remote from Philips

There are two easy examples of ways this technology can be utilizedin the lighting market. The first is as a simple on/off switch ordimming slider. This is a basic low-pain addition to a company's firstLED wall wash or table lamp. The slider can also be paired with thetuning white lights discussed earlier to select a specific colortemperature.

An on/off switch can also become a proximity switch as thesensitivity of the capacitive loop is increased. Then a hand would onlyhave to be waved near a light to turn it on. Again, this is a greatfeature that doesn't necessarily have to require any additional designwork with the LEDs themselves.

All the options discussed in this article, from tuning white lightto communication to peripheral functionality, can be integrated into acurrent design using existing application notes and firmware frommicrocontroller companies. Adding differentiation does not have to be ahuge headache for a design team unused to semiconductor integration andcan add features and value to an end product.

The LED market is a terrific opportunity for creative designers tocarve a unique niche for themselves against their growing competition,and the features of LEDs means the applications in lighting arevirtually limitless.

Designers who grasp these features will have a large advantage overtheir competition. The above differentiating concepts are the tip ofthe iceberg, and it will be exciting to see what other ideas drive themarket moving forward.

Gavin Hesse received his BSEE fromSeattle Pacific University and is now a Product Marketing Engineer for Cypress Semiconductor. He wouldlike to acknowledge the role “real” engineers play in making him lookgood. When not helping conquer the world for PSoC, Gavin can normallybe found enjoying Seattle Seahawks football in all its glory.

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