Category Archives: LEDS

Mass Manufacturing Micro-LED Displays

One of the challenges that industries and academic research groups occasionally face is that of transferring semiconductor devices of micrometer-scale from their native substrate to their respective receiving platforms. Now, researchers at the University of Strathclyde have successfully demonstrated a continuous roller printing process for picking up and transferring over 75,000 micrometer-scale semiconductor devices with very high accuracy, in a single roll. With this new method, the team has paved the way to creating a large-scale array of optical components that could be used for rapid manufacturing of micro-LED arrays.

According to the team, their unique printing process based on rollers is a way to tackle the above obstacle, and do so in a scalable manner, all the while meeting the stringent accuracy necessary for such an application. They claim their new roller technology is capable of matching the design of the device layout and has an accuracy of one micron or less. While the setup is inexpensive, it is also simple enough for users to construct it in locations with limited resources.

Large displays are made up of thousands to millions of tiny semiconductor devices. The real challenge was to manipulate these devices, such as taking them from their native substrate and placing them on the target substrate or circuit with high precision. The next hurdle was to inspect these devices, to ascertain their positional accuracy. For mass-manufacturing these displays, it is essential to not only effectively transfer them but also to find a way to look at them to assess their position and to effectively monitor the accuracy and yield.

As to how the transfer process works, the team explained that placing different materials in close proximity or in contact, develop interacting forces between them, generating adhesive forces between different material. The team uses this adhesion to pick up the devices and place them on the target surface. They use optical or adhesive coatings to enhance this adhesion, which makes the process easier.

Right now, the team is working to improve the accuracy of the printing process. At the same time, they are also trying to scale up the number of devices that the operation can transfer at a time. As the process works in terms of accuracy and yield, the team must further improve its scale and accuracy to be commercially viable.

The team is also working on a printing process for active devices. They intend to address individual microelectronic devices that they want to transfer and test such that they do not have any issues from the printing, either in the electrical or optical properties.

One of their biggest challenges is to effectively transfer a three-color display while maintaining good accuracy. The researchers feel their work will have an impact on the market and on the industry in general. By going ahead and overcoming the challenges, the researchers will need to find a method that is to a great extent compatible with the existing industry and manufacturing processes.

Micro-LED displays are making their way into cars for navigation systems, into AR and VR, in gaming monitors, and in the military for training purposes.

Nanomaterial for Improving LED Brightness and Efficiency

LEDs are a ubiquitous presence in our lives. They have replaced almost all forms of lighting devices we were using earlier, replacing incandescent lamps, fluorescent lamps, compact fluorescent lamps, mercury vapor lamps, and sodium vapor lamps. This has been possible primarily because of the efficiency and long life of LED lamps. Now there is new research to suggest ways to improve their efficiency and brightness further. This could lower their cost, leading to a further lowering of the cost of scientific tools and consumer goods.

A huge team of researchers, including engineers from the Academia Sinica in Taiwan, the SLAC National Accelerator Lab, Brookhaven, National Laboratory, Los Alamos, and the Center of Nanoscale Materials, Argonne, have managed to make stabilized perovskite nanocrystals. They will use these nanocrystals in LEDs to improve their brightness and stability substantially.

Perovskite crystals have a singular crystalline structure, giving them properties for absorbing and emitting light. This characteristic is helpful in making energy-efficient devices including gamma detectors, consumer devices, and solar cells.

Although scientists have long considered perovskite nanocrystals as a prime candidate material for LEDs, the unstable nature of the perovskites prevented them from actual implementation. The research team stabilized the crystals by embedding them in a porous structure of MOF or a framework of metal and organic substances.

Such an intriguing concept of stabilization has been accomplished earlier also. But scientists could demonstrate that only in powder form. Earlier attempts to create LEDs from perovskite nanocrystals failed as the nanocrystals degraded back to their bulk phase. This led to a loss of their nanocrystal advantages in building LEDs. In the bulk form, the perovskite is in the nanophase, and it behaves differently.

The team managed to solve the problem by creating the perovskite crystals in the emission layer in an LED, for the first time. They have demonstrated that it is possible to manufacture light-emitting diodes at a low cost with perovskite nanocrystals by embedding them in a framework of metal and organic substances. Embedding the perovskite nanocrystals in a MOF framework stabilizes them for the working conditions of the LED.

For making the MOF, the team used a framework of lead nodes as the metal precursor, and for the organic material, they used halide salts. The methylammonium bromide in the halide salts reacted with the lead in the framework, forming nanocrystals around the lead core, and trapping them in the matrix.

As the matrix isolates the nanocrystals, they cannot interact and degrade. The researchers used this method as a coating, as it is substantially cheaper than vacuum processing. Almost all inorganic LEDs in wide use today require vacuum processing.

The team claims it is possible to create bright red, green, and blue LEDs with the MOF-stabilized technique. According to them, it is also possible to create them in various shades of the three colors. They have demonstrated, for the first time, that by stabilizing perovskite nanocrystals in MOF, they can create bright and stable LEDs in a full range of colors. It is possible to create LEDs of different colors, and improve their color purity while enhancing their ability to generate light.

Driving LED Arrays

Digital signage, area illumination, and display back-lighting require large numbers of LEDs, especially of the high-brightness types. A simple arrangement is adequate for driving a single or a few LEDs. However, driving large numbers of LEDs presents a different challenge. There are issues like the optimum overall interconnection topology, the options for powering them, and then the control of the array.

A drive current from 20 to 60 mA is adequate for most single LEDs with a voltage drop of 1.8 to 4 VDC. For instance, a red LED has a nominal voltage drop of 1.8 VDC, and a white LED as high as 4.0 VDC, with other colors in between. Therefore, driving LEDs means changing over to constant-current supplies or drivers rather than using the more common constant-voltage supplies. Most designers are often less familiar with constant-current modes of supplies and their implications.

In concept, the power supply and the driver chain for LEDs are fairly simple. However, driving an array of LEDs is both simple and difficult. While driving a single LED is simple as it is a low voltage and low current load, and the driver has to operate at an efficient dc-to-dc conversion frequency of between 100 kHz and 1.5 MHz. The difficult part is the driver has to supply a constant current, which places new and difficult demands on the design of the circuitry.

Typically, the LED driver for a multi-LED array is the final stage in the power-supply chain, beginning with the AC input. There are optional low-voltage dc-to-dc conversion stages between the two, and ultimately the final DC voltage-to-current conversion immediately before the actual LED drive.

For creating an array of multiple LEDs, it is necessary for the designer to first decide the optimum combination of series, parallel, and series-parallel topology they must use. It is possible to wire up arrays of multiple LEDs as series-only, parallel-only, or as a combination of series and parallel. Each combination brings its own trade-offs for deciding the driver, its cost, reliability, physical layout options, and failure/fault handling. They must also consider the unavoidable thermal considerations and heat dissipation.

In a series-only configuration, a single power rail of the power supply supplies all the LEDs. Therefore, the current flowing through each LED is the same, allowing more or less equal brightness from the LEDs. However, an open-mode failure in any LED serves to shut down the operation for the entire chain. To prevent this from happening, most designers add a small value resistor across each LED, thereby adding to cost and space requirements.

The series-only combination has another issue, that of compliance voltage. As the chain grows longer, so must the voltage go up to deliver the current to the chain, as this voltage is the sum of the drops across all the LEDs. Regulating 20 to 60 mA at a high voltage of 150 VDC is difficult.

A parallel combination of LEDs means the driver must supply only a low compliance voltage, equal to the voltage drop across one LED. However, the power supply now has to supply a fairly large amount of current, equal to the sum total of currents of all the LEDs.

Back-Lighting with LEDs

Liquid crystal displays require back-lighting. This is because liquid crystal displays do not generate any light, and their visibility depends on light passing through the display. Opaque sections in the display become visible when they block light from behind the display. To make the display readable, manufacturers resort to providing them with light from behind the display.

The back-lighting in liquid crystal display panels may come from sources like incandescent, fluorescence, electroluminescence, woven fiber optics, or LEDs. Appearance, cost, and features consideration decide the ultimate choice for the selection of source for the back-lighting. The most popular is solid-state lighting using LEDs, as these devices offer better luminance and power efficiency, as compared to all other sources. Another advantage of LED back-lighting for LCD panels is the long life of LEDs.

Earlier, LED back-lighting typically used direct lighting, with large numbers of LEDs mounted behind the display. This arrangement provided excellent image quality along with the ability of local dimming. However, the high cost of this method did not allow it to gain market share. Rather, back-lighting technology changed over to edge-mounted LED back-lighting. An added advantage of edge-mounted LED back-lighting was that the edge-lit LCD panels could be made in extremely thin designs.

By using edge-lit LED back-lighting, manufacturers could reduce the number of LEDs necessary, by concentrating them along the edges. Initially, manufacturers used LEDs on all four edges. Very soon, they placed the LEDs along two shorter edges only, and eventually, they were placing the LEDs on only a single short edge of the LCD panel.

LEDs are a good choice for back-lighting. They are compact, operate in a wide temperature range, offer a good color selection, have a low operating voltage, and have a long operating life of at least 50 thousand hours. Over a specified range of drive current levels, LEDs offer a predominantly fixed voltage drop. However, LED back-lighting also offers some challenges. For instance, the light provided by the LEDs is uneven, which improves with a suitable light pipe or diffuser. Another challenge is the current through the LEDs depends on the ambient temperature, and requires close monitoring to allow safe operation over a wide range of temperatures.

The driver for such constant-current devices requires building up the drive voltage until it is supplying the desired current level. It reaches a stabilization point when the drive voltage equals the sum of the forward drops of all the LEDs in series. The maximum voltage of the driver limits the number of LEDs in series that it can drive at a time. However, even the simplest of drivers requires holding some voltage in reserve, for dropping across a current limiting resistor. This means a driver will never be able to apply the entire power supply voltage across a chain of LEDs.

The number of LEDs required depends on the size of the LCD panel, and its brightness. High-brightness and ultra-high-brightness LCD panels require a larger number of LEDs. Driving large numbers of LEDs requires sophisticated constant current drivers and high-efficiency power supplies.

Solderless CoB LED Holders

CoB or Chip-on-board LEDs are very popular for producing high-power lights. Many connector manufacturers provide easier and faster methods for setting and mounting the CoB LEDs in lighting fixtures. One of them is the solderless LED holders, focusing on easy and fast assembly, secure attachments, and lower costs. Numerous companies are now offering solderless CoB LED holders.

An LED holder typically holds the CoB LED before mounting on the heat sink. As the operator screws the holder on to the heat sink, the holder pushes the LED on the heat sink to allow good heat transfer. The holder also allows making electrical connection to the LED. In addition, the holder provides isolated landing zones for secondary optics such as lenses and reflectors.

TE Connectivity is one of the major producers of solderless holders for CoB LEDs. Their Z50 connector from the LUMAWISE family, conforming to the Zhaga consortium specifications, is the latest. The specifications stress on the interchangeability of light-sources and simplify general LED lighting arrangements.

Assembling the Z50 takes only five easy steps:

  • Snap the CoB into the base
  • Apply thermal grease to the LED
  • Fit cables into the Z50 base
  • Screw the assembly on to the heat sink
  • Attach secondary optics

The Z50 is available in various designs compatible with LEDs from different manufacturers. These include the SOLARIQ array, Nichicon CoB, OSRAM Opto, Philips LUMEDS, and the CXA series from Cree. One can use the holder in different ways such as for stage lights, wall washers, downlights, architectural lighting, and spotlights.

Molex offers PSI or plastic-substrate interconnect suitable for LED CoB arrays. Molex has designed these holders such that users can achieve a secure connection very fast. The interconnects are customizable as they address space constraints. Lighting designs often demand low-profile harness interfaces that the PSI addresses very well. A simple connection to the holder delivers power to the array.

Ideal for area lighting and down-lighting, the PSI system from Molex is available in custom shapes including the more common rectangular and circular as well. Other low-profile receptacles and headers are also available from Molex.

Solderless LED connectors are also available from VCC, such as their CNX 460 and CNX 440 series. The receptacles are unique as they require no tools for assembly, offering an easy and quick threaded connection. It is possible to configure the CNX 440 series to make it support up to 6 leaded IR, UC, or RGB LEDs at a time. On the other hand, it is possible to use the CNX 460 for standard 10 mm LED packages or high-flux LEDs. Both series can work with LED brands from all major manufacturers. For increased brightness, VCC offers HMC 461 and CMC 441, with Fresnel ring lens style. NEMA 4 applications can use HMC 4661 and CMS 442, also from VCC.

Providing extra stability to the leads of the LED, the CNX 460 and CNX 440 series of LED connectors have unique interconnectors. VCC has designed the connectors to easily integrate them within standalone assemblies or custom cable assemblies providing wire ends stripped for PCB connection. No crimping or soldering is necessary, as the modular panel mount from VCC offers easy and superior connection and stability.

Future of LEDs

LEDs have much to offer—small size, high efficiency, and incredible versatility—no wonder they are the most popular electronic products in the market today. Their versatility allows us to use them in horticulture, as status indicator lights, and displays with high definition. Although we are so familiar with LEDs that we hardly notice them anymore, new applications keep appearing, and engineers are forever making newer breakthroughs. That is why the LED market is still growing at a stupendous rate, especially in Europe, India, and Southeast Asia. We have listed some new technologies here:

Multicolor LEDs

After several tries, scientists have recently been able to achieve an LED that produces a blue color. This has completed the entire spectrum of LED arrays. Now, scientists have a technique that allows a single LED to produce all three primary colors. So far, rendering a full spectrum required placing three to four tiny LEDs near one another. The new technique has a big implication of making multicolored displays with color-tuned LEDs.

Furthermore, the new process dopes gallium nitride with europium, a rare earth element, and the process is compatible with current technologies involving GaN. Commercial solid-state lighting commonly uses GaN LEDs, which means we will see the new technology working in the commercial sector very soon.

Cooling with Reversed LEDs

LED physics has another significant new development. Running LEDs in reverse creates a cooling effect. A research team has demonstrated that by running LEDs backward, it is possible to achieve a tiny cooling effect of the order of 6W/m2. This is contrary to the situation in a reverse connected diode, where the diode does nothing.

Researchers are of the opinion they can improve the cooling capacity to 1000W/m2. Although the idea is not yet ready for practical implementation, wearables and mobile devices may benefit from the improved performance from using LEDs to remove heat from processors.

Lighting for Horticulture

Horticulture is benefitting from LED temperature effects and color-tuned lighting. Tomato growers in Belgium have used LEDs to stimulate plant growth. Rather than high-pressure sodium vapor (HPSV) lamps, as is the industry standard, the farmers used LED lighting for their entire 13.3-acre indoor tomato farm.

Although the light from the LEDs appears pink to human eyes, it is actually a mix of red, infra-red, blue, and white LED lights, which the farmers have mixed perfectly for stimulating tomato plant growth. Using Hyperion fittings, the farmers have used new LEDs from Cree. Now, farmers in the UK and the Netherlands are also using these new horticultural LED lamps.

The Belgian farmers were initially skeptical about using LEDs, as these have high efficiency and produce greater amounts of light than heat. They felt LED lights will not provide adequate heat during winter to keep the plants warm. However, they did not need their back-up heating system in the first winter. This proves developments in lighting is effectively reducing payback periods.

The future for LEDs looks bright, with new sources of innovation and recent technological development bringing increasingly superior practical use. Expect more new and improved products in our daily lives with these new LEDs, especially those in color tuning.

Role of LEDs in Horticulture

While LEDs have revolutionized indoor and exterior lighting methods, they have been revolutionizing operations involving indoor grow facilities. This is mainly because LEDs are highly flexible in their spectral output, while their efficiency is very high. That means they emit much lower heat.

A new standard from ASABE specifies the performance of LED lighting products for horticulture applications. The standard spells out the test methods to measure the optical radiation from LEDs in the range 280-800 nm. Note the visible spectrum covers about 390-700 nm.

According to the Standards and Technical director of ASABE, Scott Cedarquist, in horticultural applications, LED lighting has generated very high levels of interest in their projects in the last 20 years. Therefore, horticultural lighting makes use of several terminologies that are primarily focused on plants. Two of them are PPFD or Photosynthetic Photon Flus Density and PPF or Photosynthetic Photon Flux.

While PPFD measures the number of active photons falling on a surface per unit area per unit of time, PPF is the number of photons created by a lighting system per second.

Horticultural lighting primarily focuses on delivering photons that initiate photosynthesis and other processes in plants. These spur plant development as they excite electrons. Horticultural applications use LED products that are different from those used for general illumination. The difference is primarily that the former has a wider spectral output typical for horticultural applications. This is necessary as different plants respond differently to various wavelengths.

According to academic and industry research, each type of plant has a specific light recipe that helps the plant to yield higher growth in the shortest period. The recipe holds the variation in optical spectra for optimizing the overall growth of the plant, thereby improving desirable plant characteristics. For instance, increasing the potency of cannabis or the flavor of vegetables.

The light output from LEDs has another characteristic. Not only do LEDs provide a precise output spectrum, but this spectrum can also be tuned to optimize the spectrum for different plants and the phases of their life.

LED lighting products are primarily used in horticulture as vertical farms. This is due to the far lower heat output from LEDs as compared to that from other light sources. This allows the LEDs to be interspersed very close to the plants without damaging them. Therefore, facility managers are able to maximize the use of available space. This has made vertical farming very popular in urban areas. Horticulturists are making use of abandoned buildings which they are converting to grow food, thereby making new products available at cheaper rates.

The high efficiency of LEDs also helps considerably in energy savings. However, grow facility managers are more interested in the yield of the crop, and use of LEDs for high-value crops such as cannabis offer revenue increase from higher yield and shorter life cycle, rather than from energy savings. Similarly, more traditional crops such as flowers and leafy vegetables also use LED lighting not for energy savings, but rather for the ability to produce more crops in a shorter period.

Lighting for Illumination and Indication

In our industries, lights play several important roles. Primarily, industries tend to use lights for two fundamental purposes—illumination and indication. Smart visual factories use lighting intelligently. They carefully differentiate between using it for illuminating devices and for indicating them.

Fixtures for illumination light up a space in the industry, improving productivity, worker ergonomics, and enhancing safety. For instance, in huge storerooms, low bay lights illuminate areas blocked by structures shielding ceiling or high bay lights. Another example is the use of task lights that offer bright and focused light required to perform finer tasks at workstations, such as inspection or assembly. Furthermore, operators can visually monitor machine processes and examine interiors of enclosures using heavy-duty machine lights.

On the other hand, the industrial use of indication devices provides visual status updates. For instance, an indicator light at a station lets a manager know he or she is needed there. A machine alerts an operator with an indicator light regarding material refilling or a jam. Indication devices often use stack or tower lights, with each segment indicating a different status when it lights up. A change of colors and/or a flash in domed indicator lights often indicates a change in status.

So far, industries had managed to keep the two categories distinct. However, with the advent of LED lights, manufacturers are trying to combine illumination with indication and merging them into a single flexible device. For instance, strip lights for illumination purposes so far, were using only white light. Now they use RGB LED lights that normally give off a white color, but they can also modify the lights to show different statuses by giving off multiple colors. The device therefore, is suitable for ambient or task lighting with white light, but can also indicate status with colored light.

Industries are now using multicolored LED strips in the sightline of operators to provide them with unambiguous status indication, while using the same in tower lights to offer the supervisors an indication at a glance.

By combining illumination with indication, machine builders not only enhance the visual appeal of their machine, and improve its functionality, but the sleek and colorful lights also offer tangible benefits to their customers. Advantages include faster response to status change promotion, improved ergonomics and limited waste movements, ensuring the addressing of critical status updates in a timely fashion, and reducing the risk of expensive accidents and mistakes.

The combination of illumination and indication devices is convenient for not only OEMs but their customers as well. As the combined devices fit easily into the framework of the machine, which protects them, they are effective in their function. Retrofitting an existing machine with a combined indication and illumination device is easy, as only a single device needs setting up, and fitting only a few wires achieves both the functions. The industry is using such combined devices in applications involving machine lighting, workstations, intersections shared by foot traffic and mobile equipment, automatic gates, overhead doors, and for collaborative robots.

The combined indication and illumination devices are providing both OEMs and end users with exciting new possibilities. Although started as a trend, the combined devices are proving their worth in industrial applications.

How Efficient are Light Emitting Diodes – LEDS?

Almost all commercial and residential establishments are moving over to light emitting diode (LED) illumination, as they are guaranteed to be more efficient compared to other forms of lighting such as incandescent and fluorescent. Unless designed with care, LEDs can suffer from premature failure due to thermal issues. Under thermal stress, LEDs can permanently lose their brightness, while degrading much quicker than the manufacturer intended. That means designers and engineers need to balance the additional cost of emitters with the thermal design for providing not only an elegant design solution, but also the long life that solid state lighting promises.

With roughly 50% of the electrical energy produced worldwide being used for lighting, and the world population growing, the only two alternatives to meet the growing needs of energy are to either generate more or to make more efficient use of what we already have. Generating more energy can take several years to plan and install power plants, but improving the efficiency of lighting can effectively mitigate the rising trend of power consumption.

Providing over 100 lumens per watt, LEDs are being increasingly used for a large selection of general applications. When converting fixture designs for incandescent bulbs to those for LEDs, engineers faced issues because of the difference of their thermal characteristics. For instance, manufacturers publish the life curves for LEDs as a function of temperature, while fixture designers do not know how to handle the information.

Incandescent bulbs were actually heaters that emitted some visible light. Nearly 90% of the light emitted by incandescent bulbs fell into the region beyond 700 nanometers—the infrared region—invisible to the human eye, but perceptible as heat. This would often cause problems in the kitchen, with waste IR light promoting premature spoilage in food illuminated by incandescent bulbs.

LEDs produce light via a different mechanism. When electrons in the LED junction cross over a forbidden energy zone called band-gap and combine with holes, they produce light because the electrons lose energy. Physicists tailor the energy by adjusting the width of the band-gap, thereby producing various frequencies of light. For instance, a white LED actually generates intense blue or Ultra Violet light, which then excites a phosphor placed in its optical path, thereby turning it into white light.

However, the process of converting electrons to light photons within the junction of the LED is not a perfect one. A vast majority of the photons created within the junction is never emitted and ultimately recombine to produce waste heat. Additionally, Stokes Shift, the phenomenon that shifts the frequency of the LED emission in the phosphor to produce white light, also generates waste heat. Waste heat from both of these mechanisms must be removed from the LED junction to prevent severe damage.

Unlike their incandescent predecessors, LEDs rarely fail catastrophically. Their slow degradation affects the photon emission mechanism, resulting in a dimming effect. Engineers use two industry end-of-life metrics for measuring the life of LEDs. One is the L70 or time taken to reach 70% of original emission, and the other is L50 or time taken to reach 50% of the original emission. The industry uses the L70 point as the useful life of an LED fixture or bulb.

Intelligence in LED Lighting

Apart from illuminating dark spaces there is much more to LED lighting than otherwise thought of. LEDs can be connected in an intelligent network with a low-voltage IP-based infrastructure, and they become a part of a powerful network of systems. Such a system can cooperatively collect, analyze, manage, control, and respond to specific objectives based on real-time sensor feedback.

The building lit up by these LEDs now behaves as a smart building, offering better operational performance. It responds dynamically to operating issues related to power consumption and cost, increasing efficiency and efficacy. Moreover, such integrated intelligent lighting works smoothly with the other systems in the building.

The major issue confronting LED networks is decoupling from the relatively universal approach of a centralized lighting control. It makes more sense to change over to a solution that caters to the specific requirements of smaller segments across a large area within the building. Moreover, as lighting is a part of the intelligent network, it can integrate with and respond to other components on the network. Such an approach works very well for commercial office buildings, warehouses, healthcare facilities, manufacturing and industrial facilities, and other similar large or multipurpose areas, where a centralized approach will be inefficient and ineffective.

As an example, buildings are very commonly controlled through automated heating, ventilation, and air conditioning−also called the HVAC system. The HVAC has the task of monitoring and adjusting the temperature to make the building suitable for human comfort and machine performance. Moreover, it does this at optimal efficiency and cost. An intelligent LED lighting network connected to the system would allow lighting to synchronize into the same set of objectives. Now, the lighting couples actively and responds to environmental climate control.

This gives the lighting network the intelligence to increase the ability of users to adjust the light within the building to increase human productivity, concentration, positive mood, and well-being. Moreover, by adjusting light synchronized to the natural circadian cycle and adjusting the amount of light required depending on the amount of sunlight filtering through external windows, additional potential advantages can be achieved.

All intelligent LED lighting networks need power, and the key technology behind this is Power over Ethernet (PoE). This brings the equipment and low-voltage cabling necessary to connect the assets of Internet of Things (IoT) to LED fixtures. The success of IP-based infrastructure platforms makes PoE simple and available. Therefore, by using PoE as the arteries of the LED lighting systems for power and control, lighting also becomes a part of the building’s IoT asset.

PoE provides an infrastructure that is less expensive compared to copper cables, while offering a single layer for transferring power and data. Typically, the PoE system architecture consists of the PoE gateways, LED light fixtures, LED lights, smart drivers for LEDs, cable harnesses, sensors, wireless switches and dimmers. In general, PoE gateways are configured to use any one source from unregulated 48 VDC, constant voltage 24 VDC/48 VDC, or constant current.

There may be wireless PoE gateways as well, conforming to IEEE 802 standards. Usually, they run at standard frequencies such as 902 MHz in the North Americas, and at 868 MHz in Europe.