Ultra-bright LEDs. Selection, application and characteristics of LEDs: useful information and professional recommendations. LED connection diagrams

Light sources based on diodes previously could not compete with other lighting devices due to their low brightness, low power, and low light output. The development of semiconductor technology has led to the creation of ultra-bright LEDs. They are widely used in household appliances, computers, electronics, lighting, cars, advertising signs, construction equipment; as light sources and indications. In addition, ultra-bright semiconductor lighting devices can be used in harsh weather conditions.

Power LED design and light dispersion angle

Powerful, ultra-bright LEDs are designed almost the same as standard ones. The only difference is the arrangement of the crystals. In a standard diode they are installed on a special base; in an ultra-bright diode, the installation platform is equipped with a heat sink. For this reason, the device can generate a luminous flux of 100 lm.

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Components that make up a high-power semiconductor lighting device:

The body base is a metal-ceramic substrate with high thermal conductivity. Due to this, a minimum of thermal resistance is achieved and the crystal body is electrically isolated from the heat sink.
Carborundum crystals.
Substrate. It is made on the basis of carborundum and aluminum nitride. As a result, mechanical stresses do not arise in the crystal when the temperature changes.
Reflector. This function is performed by a metal case.
The lens is floating. The material from which it is made is quartz glass. The lens is not rigidly fixed in the body. Its position is maintained due to adhesion to the jelly-like sealant. Thanks to this, the occurrence of mechanical stress is eliminated and autofocus is performed over a wide temperature range.

Semiconductor lighting devices differ from standard ones in the dispersion angle.

The latter emit light evenly in all directions of space. The LED can have a dispersion angle of 15-120?. To increase this parameter, a diverging lens is used. Collective is used to narrow the angle, for example, to create spot lighting.

The brightness of the diode's light flux varies within an angle. The maximum illumination is achieved in the center, the minimum - at the edges of the scattering angle. This characteristic affects the cost of the LED. For example, a device with an angle of 180 degrees has a higher price than an LED with a parameter of 60 degrees.

Light diffusion from a high-power LED

The luminous intensity of an ultra-bright LED depends on the beam angle and color. To select the right ultra-bright LEDs, you need the following characteristics:

Operating current. This is an important parameter, because its erroneous increase contributes to the destruction of the device. Most often, the operating current of a powerful LED reaches 1 A.
Operating voltage. It is equal to the voltage drop across the device. Minimum value voltage is 1.5 V, maximum - 4 V. This characteristic depends on the color of the diode.
Average power rating. Reaches 1 W.
Emission color.
Illumination. This value is calculated for one square meter.

Power LED Polarity

A powerful LED, like a standard one, has 2 terminals: plus and minus. When connecting, polarity must be observed. There are several methods to determine it:

measurement;
connection to IP;
external examination;
searching for information in the technical passport.

For the first method, a tester is used in ohmmeter mode. The second method requires a constant voltage source. Many high-power, ultra-bright LEDs have marked leads, i.e. they have “+” and “-” written on them, which simplifies the task of determining the polarity. Also necessary information can be found in the technical data sheet of the device. However, retailers do not always provide technical documentation. In this case, you can use the Internet to search for a description of the device by its brand.

Power LED connection diagram

There are two schemes for connecting ultra-bright semiconductor devices:

without driver;
with driver.

When several diodes are connected in series, the voltage is summed. When connected in parallel, the voltage is the same. The driver is used to increase the service life of devices when the LED voltage does not match the power supply voltage.

Color characteristics

Color is the main parameter of a lighting device. Semiconductor technology does not lag behind in in this case, because powerful LEDs are capable of pleasing the eye with a wide range of colors: red, yellow, green, white, blue.

In addition, some colors have several shades: from cool to warm white, and an ultra-bright white LED will cost the same. The color of SMD LEDs affects the dispersion angle.

At the dawn of the era of LEDs, even a slight glow of an element seemed like a breakthrough, because even several pieces combined together consumed practically no energy. Time passed, and similar products developed along with it. Today you won’t surprise anyone with super-bright LEDs, which have become used everywhere. But despite their prevalence, people know little about such LED elements. Today's article will correct this omission.

High brightness LEDs: general information

Such elements can be formally divided into 2 categories. Some have increased power, others are designed in such a way that, with low electricity consumption, they are capable of producing a luminous flux that is several times greater than that of conventional analogues.

One of the representatives of such super-bright LEDs are products from Cree. The cost of such chips is quite high, which leads to the appearance of many fakes. Chinese manufacturers have especially distinguished themselves in this field. Often their products initially shine even brighter than the original, but the counterfeit quickly degrades. After only 10-15 hours of continuous operation, the diode dims until it completely fails.

If we talk about SMD components, you can also find super-bright LEDs among them, but their power consumption will be much higher, as will their dimensions. But small-sized elements can be found under the Epistar brand. Pretty good quality and long term services are the reasons for the popularity of these LEDs.

Types of such elements and their characteristics

In the manufacture of such LEDs, certain semiconductors are used. If we divide them by type, we can distinguish 2 main ones:

AlInGaP - elements of yellow, green, orange and red colors are made from it.
InGaN - white, blue, green and blue-green LED elements.

The characteristics of ultra-bright LEDs allow them to be used in completely various areas. They are used for lighting workshops, streets, and apartments. Such elements are also installed on cars as daytime running lights, side markers or low beam headlights. However, the latter option is increasingly losing popularity.

The fact is that ultra-bright LEDs get very hot during operation. After they are installed in the headlight housing, they have to work almost constantly, which leads to an increase in temperature and rapid degradation. But as dimensions that are turned on only at night, when it is much cooler outside, they have proven themselves to be quite good.

But the most common area of application for super-bright LEDs is in flashlights. Such a device with elements installed in it, for example Cree, is capable of piercing the darkness with a beam at a distance of up to 2-3 km. At the same time, its energy consumption will remain at a fairly low level. Most often, head-mounted options are used by fishermen when fishing at night - the light flux reaches the bottom through a water thickness of 3-4 meters.

Application of LEDs in the automotive industry

Not all LED elements are suitable for cars. Many species require only 2-3 V power, while on-board network cars - 12 V. That is why the manufacturer offers specialized LED elements for cars. The main thing here is to understand where super-bright 12-volt LEDs can be placed, and where they should not be mounted. After all, if such elements are placed on brake lights, there is a high probability that they will blind the driver of the car behind, and this will not lead to anything good. Also, you should not install them in the panel illumination - driving in the dark with such “tuning” will be impossible.

It is acceptable to install super-bright 12-volt LEDs in reversing lights, side lights, and also as interior lighting. In these cases, the installation of such equipment will be justified. It is possible to include LEDs in the circuit as low beams, but in this case it is necessary to organize high-quality air cooling. An example of this use of ultra-bright elements is Lexus cars.

Operating voltage of LED elements

Many people pay too much attention to this parameter great value without understanding its essence. The point here is this. If, for example, it is written that the rating of a super-bright LED is 3 volts, this figure only means the voltage drop across it. A more important parameter is the operating current of the element, which can reach 1 A.

What to consider when choosing and installing

When choosing super-bright LEDs for a car or other application, you should pay attention not only to the characteristics declared by the manufacturer, but also to appearance product, quality of its manufacture. Often a fake can be detected even by visual inspection with the naked eye. Counterfeit LEDs may have uneven edges, and the chip under the lens is often located asymmetrically.

A lower price compared to the market average should also alert the buyer. Before going to the store, it is better to familiarize yourself with the prices on the official websites of manufacturers of such products - this will protect you from purchasing low-quality goods.

Installation of ultra-bright LEDs also requires compliance certain rules. Even with good ventilation, if there is an option for an additional radiator, it is worth doing. Thermal paste should be used to connect the chip to the cooler.

Pros and cons of using super bright elements

Like any equipment, such LEDs have supporters and opponents. According to surveys conducted by an independent company, about 30% of respondents were “against” the use of such LED elements. The most interesting thing is that the reason for the occurrence negative attitude began the use of super-bright LEDs for flashlights. People said that it is very harmful when such a beam is shined into the eyes. A strange opinion came from residents of the United States of America, where surveys were conducted on this topic.

Basically, the use of such elements in lighting devices has more positive than negative qualities. Of course, if you purchase a high-quality, branded product, its cost will be high, but it will last much longer than a low-quality cheap diode. The main thing in this matter is to compare your capabilities with the level of need for such an acquisition.

To summarize the above

Ultra-bright LEDs are truly the pinnacle of LED element development today. Don't complain that their cost is quite high. Like any other device, they will fall in value over time. Although it is possible that engineers will develop some other new product that will outshine the ultra-bright LED. Based on the pace of progress in all technical fields, this cannot be ruled out.

If it were unprofitable for humanity to use LEDs, then only a limited circle of scientists would know about them. But the source with a fundamentally new type of radiation turned out to be very effective. Over time, small crystals began to be combined several times in one case, and they also learned to grow super crystals of increased sizes. The result is ultra-bright LEDs, or, as they are also called, super-bright LEDs, with the widest possible application possibilities.

The elementary LED itself is designed for a voltage of more than 3-5 Volts. Its characteristics make it possible to use such an element for display purposes and for decorative lighting. However, scientists managed to develop more powerful devices using a number of tricks. This is how super-bright 12-volt super LEDs were born. Using a driver, a 12 Volt device can be connected to a higher voltage, including a 220 Volt network.

Pulse brightness change

The main advantage of an ultra-bright 12-volt super LED is its low energy consumption and at the same time bright light. An additional advantage is a controlled change in the brightness of the LEDs, for which a controller is used. It turns out that a device that uses ultra-bright LEDs can reduce or increase the intensity of its radiation.

To control the brightness of LEDs, pulse width modulation is used. With this method, you can reduce the brightness by periodically turning off the light bulb. The lamp pulsates, and the pulsation parameters will determine the intensity of its glow.

This operating principle allows you to expand the capabilities of high-brightness LEDs. As a result, we get functional ones:

flashlights;
car headlights;
light alarm;
home lamps.

Note that the alarm uses a flashing LED of 5, 12 and even 14 volts, which helps to draw attention to the display cases, counter or cash register window. Low voltage devices are also used. A flashing LED is designed slightly differently than a regular indicator light. A pulse generator chip is placed in the housing where the crystal is located.

Most often, super-bright 12-volt LEDs replace halogen lamps, which provide directional light. That is why, when producing lamps using LEDs, they are made with a standard base E14, GU10 and some others.

Important Features

All super bright sources have the same light characteristics as conventional LEDs:

luminous flux;
brightness;
light output;
illumination

When installing a 12-volt LED lamp on a particular device, you need to understand that its effectiveness depends on the wavelength of the radiation or, more simply, on the color. Here is a table showing the dependency.

But by studying these characteristics, not every person will be able to understand which device is right for him. It is much easier to decide by looking at the electrical parameters: voltage, maximum forward current, device power.

In addition to this, there are other characteristics. Super-bright LEDs can be created on the basis of a single crystal or be multi-chip. Characteristics such as wavelength and color temperature are responsible for the color of the glow. Important parameters are the beam angle, body size and the number of LEDs in one lamp.

The development of new models has led to the emergence of another distinguishing feature– body shape. A popular package for ultra-bright 12-volt LEDs is the “piranha”, which has four terminals. There are also dual terminal and surface mount models available.

Each device model has its own parameter table, by looking into which you can find out the operating features of this device.

A few caveats

The main problem in the production of super-bright LEDs is the problem of heat dissipation. The LED must not overheat, otherwise the light intensity will irreversibly decrease. Super-bright, high-power devices are especially susceptible to overheating, so when installing them yourself, it is necessary to ensure their cooling using a radiator.

Pay special attention to the electrical parameters, avoiding connecting to a voltage that is higher than that specified in the instructions, and providing only the permissible current. Thus, super-bright sources will be able to shine for as long as possible.

Handle the copper leads with care, as kinking or severe deformation will cause the signal strength to change.

Lighting devices that use super-bright LEDs as light sources will no longer surprise anyone. The demand for such devices is constantly growing, this is directly related to the low power consumption of these devices. Considering that about 25-35% of consumed electricity is spent on lighting, the savings will be very noticeable.

But given the relatively high cost of ultra-bright LEDs, due to their design features, it is not yet timely to talk about a complete transition to this type of lighting. According to experts, this process will take from 5 to 10 years, which is exactly how long it will take to debug and implement new technologies.

Briefly about efficiency

The efficiency of a lighting device is generally considered to be the ratio of the luminous flux produced (measured in lumens) to the electricity consumed (watts). High quality lamp with an incandescent filament it has an efficiency of about 16 lumens per watt, fluorescent (energy saving) is four times more (64 lm/W), for long daylight lamps this figure is around 80 lm/W.

The efficiency of ultra-bright LEDs currently produced in large quantities is approximately the same as that of fluorescent lamps. Please note that we are talking about mass production. As for the theoretical limit for ultra-bright LED sources, it is determined by a threshold of 320 lm/W.

As many manufacturers promise, in the next few years the efficiency can be increased to 213 lm/W.

Impact of design features on cost

To produce super-bright LED light sources, one of two methods can be used:

To obtain light close in spectrum to white, three crystals are used installed in one housing. One is red, the second is blue and the third is green;
a crystal is used that emits in the blue or ultraviolet spectrum; it illuminates a lens coated with a phosphor, as a result the radiation is converted into light that is close in spectrum to natural light.

Despite the fact that the first option is more effective, its implementation is somewhat more expensive, which negatively affects its prevalence. In addition, the spectrum of light emitted by such a source differs from natural light.

Devices manufactured using the second technology are less efficient. It is also worth considering that the phosphor contains a complex composite based on cerium and yttrium, which themselves are not cheap. Actually, this explains the relatively high cost of ultra-bright white light LEDs. The design of such a device is shown in the figure.

Designations:

A – printed conductor;
B – base with increased thermal conductivity;
C – protective housing of the device;
D – solder paste;
E – LED crystal emitting ultraviolet or blue light;
F – phosphor coating;
G – glue (can be replaced with a eutectic alloy);
H – wire connecting the crystal and the output;
K – reflector;
J – heat-dissipating base;
L – power output;
M – dielectric layer.

Installation features

The operation of ultra-bright LEDs is influenced by the degree of heating of the crystal and the p-n junction. The life of the device directly depends on the first, and the level of luminous flux depends on the second. Therefore, for long-term service of ultra-bright LEDs, it is necessary to organize a reliable heat sink, this is done using a radiator.

It should be taken into account that the thermally conductive bases of these semiconductors tend to conduct electricity. Therefore, when several elements are installed on one radiator, care should be taken to ensure reliable electrical insulation of the bases.

The remaining installation rules are almost the same as for conventional diodes, that is, polarity must be observed both when installing the part itself and when connecting the power.

Nutritional Features

Considering the relatively high cost of ultra-bright LEDs, it is very important to use reliable and high-quality power supplies for their operation, since these semiconductor elements are critical to current overload.

After an abnormal operation, the device may remain operational, but the power of the emitted light flux will be significantly reduced. In addition, such an element is likely to cause damage to other LEDs connected together.

Before talking about drivers for ultra-bright LEDs, let's briefly talk about the features of their power supply. First of all, the following factors need to be taken into account:

the power of the light flux emitted by these elements directly depends on the amount of electric current flowing through them;
Ultra-bright LEDs are characterized by a nonlinear current-voltage characteristic (volt-ampere characteristic);
temperature has strong influence on the current-voltage characteristics of these semiconductor devices.

Below is shown the change in the current-voltage characteristic at the temperature of the semiconductor element (ultra-bright SMD LED) of 20 ° C and 70 ° C.

As can be seen from the graph, when a stable voltage of 2 V is applied to a semiconductor, the electric current passing through it changes depending on the temperature. When the crystal is heated to 20°C, it will be equal to 14 mA, when the temperature rises to 70°C, this parameter will correspond to 35 mA.

The result of such a difference will be a change in the power of the light flux at the same supply voltage. Based on this, it is necessary to stabilize not the voltage, but the electric current passing through the semiconductor.

Such power supplies are called LED drivers, they are ordinary current stabilizers. This device can be purchased ready-made or assembled yourself; in the next section we will provide several typical driver circuits.

Homemade LED driver

We will present to your attention several driver options based on specialized microcircuits from Monolithic Power System, the use of which significantly simplifies the design. The circuits are given as an example; a full description of the typical connection can be found in the datasheet for the microcircuits.

Option one is based on the MP4688 step-down converter.

This driver can operate with voltages from 4.5 to 80 V, the maximum output current threshold is 2 A, which allows you to power the lamp with ultra-bright high-power LEDs. The level of electric current passing through the LEDs is regulated by resistance R FB. The implementation of PWM dimming with a frequency of 20 kHz allows you to smoothly change the electric current flowing through the LED.

The second version of the driver is based on the MP2489 chip. Its compact housing (QFN8 or TSOT23-5) makes it possible to place the driver in the MR16 socket used by halogen lamps, which allows replacing the latter with LED lamps. A typical MP2489 connection diagram is shown in the figure.

The above circuit allows you to connect two parallel LEDs, each of which has an operating current of 350 mA.

The latest version of the driver based on the MP3412 chip, which can be used in portable flashlights. Distinctive feature Such a circuit allows operation from a AA AA battery.

Founded in 1987 in the United States of America (USA), Cree set a course for creating semiconductor devices based on silicon carbide (SiC) and gallium nitride (GaN). Collaboration with Japanese colleagues contributed to rapid development new technology and as a result, the appearance of the first powerful LEDs XLamp series. In 2006, the developers set a milestone of 100 lm/W, in 2010 – 200 lm/W, and in 2012 – 250 lm/W, breaking the next theoretical maximum for crystals of this type. Today, Cree regularly manages to prove to theorists the inexhaustible possibilities in improving solid-state light sources.

In addition to the world-famous XLamp, the American corporation holds a leading position in the production of low-current, ultra-bright High-Brightness LEDs, which are no less in demand in the design electronic technology. Cree's products are not limited to light-emitting diodes. Her laboratories successfully implement projects to create high-voltage Schottky diodes and microwave field-effect transistors.

Powerful LEDs

Having made several groundbreaking discoveries over the past 5 years and introduced new LED and COB LEDs to the world, Cree continues to improve the power and efficiency of its products. The first group of LEDs is represented by powerful samples of the XLamp series, which consists of several families that differ in production technology, form factors and some technical parameters. In the XLamp series there are two large groups light-emitting diodes: single-chip and multi-chip.

Single-chip

Cree single-chip LEDs are the smallest members of the XLamp family. Possessing high density and luminous intensity, the geometric dimensions of the XQ series LEDs are 1.6x1.6 mm. The LEDs in this series have changed the concept of the standard luminous flux distribution pattern, directing it closer to the edges. This innovative approach makes it possible to implement luminaires with a wide beam angle using fewer LEDs. The XQ series LED beam angle ranges from 100° to 145°. One of the latest developments from Cree is the XQ-E High Intensity LEDs. American engineers managed to squeeze 3 W of power out of a tiny crystal, converting it into a luminous flux of 334 Lm.

The entire line of light-emitting diodes, built on a single chip, has excellent color rendering (CRI 70–90).

Multichip

Having reached the 3000 mA mark, manufacturers of solid-state light sources began to increase power by increasing the voltage. The American company Cree has achieved great results in this direction, offering the world new LED supply voltage standards. Cree offers several series of multi-chip LEDs rated from 6 to 72 volts. All multi-chip SMD LEDs with white light from Cree can be divided into three large subgroups: high voltage power supply, power up to and above 4 W. Separate subgroups of multi-chip light-emitting diodes include high-power COB matrices, color and Royal Blue LEDs.

Up to 4 W

The line of LEDs on several chips, with a total power of up to 4 W, is represented by 6 light-emitting diodes in packages: MX and ML. By technical parameters they are united by a glow angle of 120° and two possible color shades: cold and warm white. The MX series has found a compromise between light output and power consumption. By increasing the supply voltage, the developers managed to achieve high reliability without reducing the quality of light.

LEDs of the ML and MX series are positioned on the market as devices with an average price.

Over 4 W

Not stopping there, Cree continued the “race for lumens” and presented a new generation of multi-chip LEDs with a power of more than 4 W. Crystals of the MT-G series are the largest representatives of the group, with a power of up to 25 W.
A new product from Cree is the XHP (Extreme High Power) series LEDs, which are presented in 4 models. The largest representative is made in a 7x7 mm case and, consuming 12 W, produces 1710 lm. The advent of XHP gave impetus to the development of new lighting designs with lower costs for secondary optics and cooling systems.

High voltage supply (12–46 V)

High-voltage LEDs HVW (High-Voltage White) from Cree are a tandem of a huge luminous flux and a small housing size. Having compact dimensions, they are an order of magnitude superior to LED assemblies, thanks to which they began to be used in the production of retrofit lamps. Lamps with E14 and E27 sockets based on HVW have high efficiency, smaller dimensions of the driver and radiator than their counterparts with low-voltage light-emitting diodes.

Colored

In parallel with the modernization of white LEDs, Cree is increasing the potential of color LEDs, which are in demand in decorative lighting of interiors, external lighting of architectural objects and artificial lighting of plants. The XP-E series, with a wide choice of colors, features high light output in a 3.45 x 3.45 mm housing. The XQ-E series has even smaller dimensions of 1.6x1.6 mm, which attracted the attention of plant growers. The XQ-E HI's compact design and lack of a dome lens provide the focused beam of light needed for efficient growth of greenhouse plants. LED series MC-E RGB+W and XM–L RGB+W have adjustable color temperature and brightness, as well as the ability to emit cool white light.

XLamp Royal Blue LEDs from Cree are included in a separate group due to their design features, namely, “remote phosphor” technology. Its essence is to apply a phosphor not to the crystal, but to the inner surface of the secondary optics. The result is a highly efficient beam of light with a narrow “deep blue” emission spectrum. XLamp Royal Blue is produced in standard housings XP, XR, XQ, XB, XT, ML and has a lower cost.

COB (Chip-on-Board) technology continues to improve, increasing power through improved technology and increased LED density. Cree's COB line is represented by the CXA and CXB series. The size of the largest CXA matrix is 34.85x34.85 mm, and its luminous flux is 12,000 lm. Improved CXB dies are manufactured on the new CS5 platform, but are completely interchangeable with CXA. For example, the specialized LED CXB 3590 Studio is a new generation of the COB line with a CRI index greater than 95, intended for building photographic equipment.

High-Brightness LEDs

Cree ultra-bright LEDs make up the second large group - High-Brightness, whose representatives are distinguished by low current values from 20 to 70 mA. The group includes 4 lines of LEDs, which differ in design. Thanks to this unification, manufacturers are able to design structures of different form factors and purposes.

PLCC

Cree's PLCC line consists of LEDs designed for surface mount applications. Regardless of the color of the glow, they are collected on one or more crystals. The line includes large assortment light-emitting SMD diodes of different colors and sizes. Among the new products, it is worth highlighting the CLYBA-FKA RGB diode in the PLCC-6 package, which is used in the formation of a ticker board.

P4

The next representative of super-bright LEDs is SuperFlux, better known as “Piranha”. Epoxy body square shape with a concave, convex or oval lens, evenly distributes the light flux at a given scattering angle. Four metal pins guarantee reliable fastening in conditions of high vibration. LED P4 from Cree is installed in floodlights, car signal lights, etc.

Round

Cree's new generation of round, low current LEDs delivers superior illumination. Their body is made of optical epoxy resin with a diameter of 5 mm. The current consumption is only 20 mA. Colored round LEDs have several modifications, varying in luminous intensity and luminous angle. White C535A-WJN and C503D-WAN are produced without stoppers, other models are equipped with stoppers on the pins.

Oval

The production of oval LEDs is focused on creating large-sized LED screens, which is in demand when creating advertising billboards all over the world. Cree oval LEDs have a housing size of 4 mm. Their unique design allows light to be emitted in two directions: the X-axis and the Y-axis, as shown in technical specifications. Along with their round counterparts, they are designed for a current of 20 mA and are resistant to sunlight, temperature and humidity changes. Oval LEDs have lower luminous intensity due to large angle dispersion.

The American company Cree supplies more than three-quarters of the world's demand for silicon carbide, suitable for the production of semiconductors, including LEDs. Having a full production cycle from growing crystals to creating lamps, the corporation directly or indirectly participates in the technical re-equipment of lighting systems in many enterprises around the world.

Reducing the cost of high-power LEDs and reducing the gap between development and serial production are two indisputable facts that confirm the reliability of cooperation with Cree. The company operates in accordance with the RoHS directive, which limits the content harmful substances in products supplied to the market.