Types and types of LEDs - a complete classification. LED characteristics: current consumption, voltage, power and light output Flat LEDs

Since the invention of electric lighting, scientists have created more and more economical sources. But a real breakthrough in this area was the invention of LEDs, which are not inferior in terms of luminous flux to their predecessors, but consume many times less electricity. Their creation, starting from the first indicator element and ending with the brightest Cree diode to date, was preceded by a huge amount of work. Today we will try to analyze the various characteristics of LEDs, find out how these elements have evolved and how they are classified.

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The principle of operation and the device of light diodes

LEDs are distinguished from the usual lighting devices by the absence of a filament, a fragile bulb and gas in it. This is a fundamentally different element. In scientific terms, the glow is created due to the presence of p- and n-type materials in it. The first accumulate a positive charge, and the second - a negative one. P-type materials accumulate electrons in themselves, while holes are formed in n-type materials (places where electrons are absent). At the moment when an electric charge appears on the contacts, they rush to the p-n junction, where each electron is injected precisely into the p-type. From the side of the reverse, negative contact of the n-type, as a result of such a movement, a glow occurs. It is due to the release of photons. However, not all photons emit light visible to the human eye. The force that makes the electrons move is called the LED current.

This information is of no use to the general public. It is enough to know that the LED has a solid housing and contacts, which can be from 2 to 4, and that each LED has its own nominal voltage required for glowing.

Good to know! Connection is always made in the same order. This means that if a “+” is connected to the “-” contact on the element, then there will be no glow - p-type materials simply cannot be charged, which means there will be no movement towards the transition.

Classification of LEDs according to their field of application

Such elements can be indicator and lighting. The former were invented earlier than the latter, while they have long been used in radio electronics. But with the advent of the first lighting LED, a real breakthrough in electrical engineering began. Demand for lighting devices of this type is steadily growing. But progress does not stand still - more and more new species are invented and introduced into production, which are becoming brighter, without consuming more energy. Let's take a closer look at what LEDs are.

Indicator LEDs: a bit of history

The first such red LED was created in the middle of the 20th century. Although it had low energy efficiency and emitted a dim glow, the direction turned out to be promising and developments in this area continued. In the 70s, green and yellow elements appear, and work on their improvement does not stop. By the 90th year, the strength of their luminous flux reaches 1 Lumen.

1993 is marked by the appearance in Japan of the first blue LED, which was much brighter than its predecessors. This meant that now, by combining three colors (which make up all the shades of the rainbow), you can get any. In the early 2000s, the luminous flux already reaches 100 Lumens. Nowadays, LEDs do not stop improving, increasing the brightness without increasing the power consumption.

Use of LEDs in residential and industrial lighting

Now such elements are used in all industries, whether it is mechanical or automotive, lighting of production workshops, streets or apartments. If we take the latest developments, we can say that even the characteristics of LEDs for flashlights are sometimes not inferior to the old 220 V halogen lamps. Let's try to give one example. If we take the characteristics of a 3 W LED, then they will be comparable to those of an incandescent lamp with a consumption of 20-25 W. It turns out that energy savings are almost 10 times, which, with daily constant use in the apartment, gives a very significant benefit.

What are the advantages of LEDs and what are their disadvantages?

Much can be said about the positive qualities of light diodes. The main ones can be called:

As for the negative sides, there are only two of them:

Operates only with constant voltage;
It follows from the first - the high cost of lamps based on them due to the need to use (an electronic stabilizing unit).

What are the main characteristics of LEDs?

When choosing such elements for a particular purpose, everyone pays attention to their technical data. The main things to pay attention to when purchasing devices based on them:

consumption current;
Rated voltage;
power consumption;
color temperature;
the power of the luminous flux.

This is what we can see on the label. In fact, there are many more features. Let's talk about them now.

LED current consumption - what is it

The current consumption of the LED is 0.02 A. But this only applies to elements with a single crystal. There are also more powerful light diodes, which can include 2, 3 or even 4 crystals. In this case, the current consumption will increase, a multiple of the number of chips. It is this parameter that dictates the need to select a resistor that is soldered at the input. In this case, the resistance of the LED prevents the high current from instantly burning the LED element. This may be due to high mains current.

Rated voltage

The voltage of an LED is directly related to its color. This is due to the difference in materials for their manufacture. Let's consider this dependence.

LED color	Material	Forward voltage at 20 mA
		Typical value (V)	Range (V)
IR	GaAs, GaAlAs	1,2	1,1-1,6
Red	GaAsP, GaP, AlInGaP	2,0	1,5-2,6
Orange	GaAsP, GaP, AlGaInP	2,0	1,7-2,8
Yellow	GaAsP, AlInGaP, GaP	2,0	1,7-2,5
Green	GaP, InGaN	2,2	1,7-4,0
Blue	ZnSe, InGaN	3,6	3,2-4,5
White	Blue/UV diode with phosphor	3,6	2,7-4,3

LED resistance

By itself, the same LED can have a different resistance. It changes depending on the inclusion in the circuit. In one direction - about 1 kOhm, in the other - a few MΩ. But there is a nuance here. The resistance of the LED is non-linear. This means that it can vary depending on the voltage applied to it. The higher the voltage, the lower the resistance will be.

Light output and beam angle

The angle of the light flux of LEDs may vary, depending on their shape and material of manufacture. It cannot exceed 120 0 . For this reason, if greater dispersion is required, special reflectors and lenses are used. This is the quality of "directional light" and contributes to the greatest luminous flux, which can reach 300-350 lm for a single 3 watt LED.

Power of LED lamps

LED power is a purely individual value. It can vary in the range from 0.5 to 3 watts. It can be determined using Ohm's law. P=I × U , Where I is the current strength, and U - LED voltage.

Power is a pretty important indicator. Especially when it is necessary to calculate what is needed for a particular number of elements.

Colorful temperature

This setting is similar to other lamps. The temperature spectrum is closest to that of LED fluorescent lamps. The color temperature is measured in K (Kelvin). The glow can be warm (2700-3000K), neutral (3500-4000K) or cold (5700-7000K). In fact, there are many more shades, here are the main ones.

LED chip size

It will not be possible to measure this parameter on your own when buying, and now it will become clear to the dear reader why. The most common sizes are 45x45 mil and 30x30 mil (corresponding to 1 W), 24x40 mil (0.75 W) and 24x24 mil (0.5 W). If translated into a more familiar measurement system, then 30x30 mil will be equal to 0.762x0.762mm.

There can be many chips (crystals) in one LED. If the element does not have a phosphor layer (RGB - color), then the number of crystals can be counted.

Important! You should not buy very cheap Chinese-made LEDs. They can be not only of low quality, but their characteristics are most often overestimated.

What are SMD LEDs: their characteristics and difference from conventional ones

A clear decoding of this abbreviation looks like Surface Mount Devices, which literally means "mounted on the surface." To make it clearer, we can recall that ordinary cylindrical light diodes on legs are recessed into the board and soldered on the other side. In contrast, SMD components are fixed with paws on the same side where they themselves are. This installation makes it possible to create double-sided printed circuit boards.

Such LEDs are much brighter and more compact than conventional ones and are elements of a new generation. Their dimensions are indicated in the marking. But do not confuse the size of the SMD LED and the crystal (chip) of which there can be many in the component. Let's take a look at some of these light diodes.

LED SMD2835 parameters: dimensions and specifications

Many beginners confuse the marking SMD2835 with SMD3528. On the one hand, they should be the same, because the marking indicates that these LEDs have a size of 2.8x3.5 mm and 3.5 by 2.8 mm, which is the same. However, this is misleading. The technical characteristics of the SMD2835 LED are much higher, while it has a thickness of only 0.7 mm versus 2 mm for the SMD3528. Consider SMD2835 data with different power:

Parameter	Chinese 2835	2835 0.2W	2835 0.5W	2835 1W
Light flux strength, Lm	8	20	50	100
Power consumption, W	0,09	0,2	0,5	1
Temperature, in degrees C	+60	+80	+80	+110
Consumption current, mA	25	60	150	300
Voltage, V	3,2

As you can understand, the technical characteristics of the SMD2835 can be quite diverse. It all depends on the quantity and quality of the crystals.

5050 LED Characteristics: Larger SMD Component

Quite surprisingly, with large dimensions, this LED has a lower luminous flux than the previous version - only 18-20 Lm. The reason for this is the small number of crystals - usually there are only two of them. The most common application of such elements is found in LED strips. The density of the strip is usually 60 pcs/m, which gives a total of about 900 lm/m. Their advantage in this case is that the tape gives a uniform calm light. In this case, the angle of its illumination is maximum and equal to 120 0 .

Such elements are produced with a white glow (cold or warm shade), one-color (red, blue or green), three-color (RGB), as well as four-color (RGBW).

Characteristics of SMD5730 LEDs

Compared to this component, the previous ones are already considered obsolete. They can already be called even super-bright LEDs. 3 volts, which feed both 5050 and 2835, give up to 50 lm at 0.5 watts here. The technical characteristics of the SMD5730 are an order of magnitude higher, which means they need to be considered.

Still, this is not the brightest LED of SMD components. Relatively recently, elements appeared on the Russian market that literally “plugged in the belt” all the rest. About them now and will be discussed.

Cree LEDs: characteristics and technical data

To date, there are no analogues of Cree products. The characteristics of their ultra-bright LEDs are truly amazing. If the previous elements could boast of a luminous flux of only 50 lm from one chip, then, for example, the characteristics of the XHP35 LED from Cree speak of 1300-1500 lm from one chip. But their power is greater - it is 13 watts.

If we summarize the characteristics of various modifications and models of LEDs of this brand, we can see the following:

The strength of the luminous flux of SMD LED "Cree" is called a bin, which must be affixed to the package. Recently, there have been a lot of fakes for this brand, mostly made in China. When buying, it is difficult to distinguish them, but after a month of use, their light dims and they cease to differ from others. At a fairly high cost, such an acquisition will be a rather unpleasant surprise.

We offer you a short video on this topic:

Checking the LED with a multimeter - how to do it

The simplest and most affordable way is "dialing". Multimeters have a separate switch position specifically for diodes. Having switched the device to the desired position, we touch the probes to the legs of the LED. If the display shows the number "1", the polarity should be reversed. In this position, the multimeter's buzzer should beep and the LED should be on. If this does not happen, then it is out of order. If the light diode is working, but does not work when soldered into the circuit, there may be two reasons for this - its incorrect location or the failure of the resistor (modern SMD components already have it built in, which will be clear in the process of “ringing”).

Color marking of light diodes

There is no generally accepted global labeling of such products; each manufacturer designates the color as it suits him. In Russia, LED color marking is used, but few people use it, because the list of elements with letter designations is quite impressive and hardly anyone wants to remember it. The most common letter designation, which many consider generally accepted. But such marking is more common not on powerful elements, but on LED strips.

Deciphering the LED strip marking code

In order to understand how the tape is marked, you need to pay attention to the table:

Position in code	Purpose	Notation	Deciphering the designation
1	Light source	LED	Light-emitting diode
2	Glow color	R	Red
		G	Green
		B	Blue
		RGB	Any
		CW	White
3	Mounting method	smd	Surface Mounted Device
4	Chip size	3028	3.0 x 2.8mm
		3528	3.5 x 2.8 mm
		2835	2.8 x 3.5 mm
		5050	5.0 x 5.0mm
5	Number of LEDs per meter length	30
		60
		120
6	Degree of protection:	IP	International Protection
7	From the penetration of solid objects	0-6	According to GOST 14254-96 (IEC standard 529-89) "Degrees of protection provided by enclosures (IP code)"
8	From liquid penetration	0-6

For example, let's take a specific LED CW SMD5050/60 IP68 marking. From it you can understand that we have a white LED strip for surface mounting. The elements installed on it have a size of 5x5mm, in the amount of 60 pcs/m. The degree of protection allows it to work under water for a long time.

What can be done from LEDs with your own hands?

This is a very interesting question. And if you answer it in detail, then it will take a lot of time. The most common use of light diodes is the illumination of suspended and stretch ceilings, the working area in the kitchen, or even a computer keyboard.

Expert opinion

Engineer-designer of ES, EM, EO (power supply, electrical equipment, interior lighting) ASP North-West LLC

Ask a specialist

“For the operation of such elements, a power stabilizer or controller is required. It can even be taken from an old Chinese garland. Many "craftsmen" write that a conventional step-down transformer is enough, but this is not so. In this case, the diodes will blink.”

Current stabilizer - what function does it perform

An LED stabilizer is a power supply that steps down the voltage and equalizes the current. In other words, it creates conditions for the normal operation of the elements. At the same time, it protects against overvoltage or undervoltage on the LEDs. There are stabilizers that can not only regulate the voltage, ensuring the smooth decay of the light elements, but also control the color or flicker modes. They are called controllers. Similar devices can be seen on garlands. They are also sold in electrical stores for switching with RGB tapes. Such controllers are equipped with remote controls.

The scheme of such a device is not complicated, and if desired, the simplest stabilizer can be made with your own hands. To do this, you only need a little knowledge in radio electronics and the ability to hold a soldering iron in your hands.

daytime running lights for car

The use of light diodes in the automotive industry is quite common. For example, DRLs are made exclusively with their help. But if the car is not equipped with running lights, then their purchase can hit the pocket. Many car enthusiasts make do with cheap LED strip, but this is not a very good idea. Especially if the strength of its luminous flux is small. A good way out can be the purchase of a self-adhesive tape on Cree diodes.

It is quite possible to make DRLs with the help of those that have already failed, by placing new, powerful diodes inside the old cases.

Important! Daytime running lights are designed specifically to ensure that the car was visible during the day, and not at night. It makes no sense to check how they will shine in the dark. DRLs should be visible in sunlight.

Flashing LEDs - what is it for?

A good option for using such elements would be a billboard. But if it is statically glowing, then it will not attract due attention. The main task is to assemble and solder the shield - this requires some skills, which are not difficult to acquire. After assembly, you can mount the controller from the same garland. The result is a flashing advertisement that will clearly attract attention.

Color music on light diodes - is it difficult to do it

This job is no longer for beginners. In order to assemble a full-fledged color music with your own hands, you need not only an accurate calculation of the elements, but also knowledge of radio electronics. But still, its simplest version is quite within the power of everyone.

In electronics stores you can always find a sound sensor, and many modern switches have it (light on cotton). If you have an LED strip and a stabilizer, then by running “+” from the power supply to the strip through a similar cracker, you can achieve the desired result.

Voltage indicator: what to do if it burns out

Modern indicator screwdrivers consist of just a light diode and resistances with an insulator. Most often it is an ebonite insert. If the element inside burns out, it is quite possible to replace it with a new one. And the color will be chosen by the craftsman himself.

Another option is to make a chain continuity. To do this, you need 2 finger batteries, wires and a light diode. Having connected the batteries in series, we solder one of the legs of the element to the plus of the battery. The wires will go from the other leg and from the minus of the battery. As a result, when the diode is closed, it will light up (if the polarity is not reversed).

LED wiring diagrams - how to do it right

Such elements can be connected in two ways - in series and in parallel. In this case, we must not forget that the light diode must be positioned correctly. Otherwise, the circuit will not work. In ordinary elements with a cylindrical shape, this can be determined as follows: a flag is visible on the cathode (-), it is slightly larger than the anode (+).

How to Calculate LED Resistance

Calculating the resistance of a light diode is very important. Otherwise, the element will simply burn out, unable to withstand the magnitude of the network current.

This can be done using the formula:

R \u003d (VS - VL) / I, Where

VS - supply voltage;
VL – rated voltage for the LED;
I - LED current (usually it is 0.02 A, which is equal to 20 mA).

Everything is possible if desired. The scheme is quite simple - we use a power supply from a broken mobile phone or any other. The main thing is that it has a rectifier. It is important not to overdo it with the load (with the number of diodes), otherwise there is a risk of burning the power supply. A standard charger can easily withstand 6-12 elements. You can mount a colored backlight for a computer keyboard by taking 2 blue, white, red, green and yellow elements. It turns out pretty nice.

Helpful information! The voltage that the power supply outputs is 3.7 V. This means that the diodes must be connected in series with switched pairs in parallel.

Parallel and serial connection: how they work

According to the laws of physics and electrical engineering, with a parallel connection, the voltage is distributed evenly over all consumers, remaining unchanged on each of them. With sequential installation, the flow is divided and on each of the consumers it becomes a multiple of their number. In other words, if you take 8 light diodes connected in series, they will work normally from 12 V. If they are connected in parallel, they will burn out.

Connecting 12 V light diodes as the best option

Any LED strip is designed to be connected to a stabilizer that produces 12 or 24 V. Today, a huge range of products from various manufacturers with these parameters is presented on the shelves of Russian stores. But still, 12 V tapes and controllers predominate. This voltage is safer for humans, and the cost of such devices is lower. The independent connection to the 12 V network was mentioned a little higher, but there should be no problems with connecting to the controller - they are accompanied by a diagram that even a schoolboy will understand.

Finally

The popularity that light diodes are gaining cannot but rejoice. After all, it makes progress move forward. And who knows, maybe in the near future new LEDs will appear, which will be an order of magnitude higher in terms of characteristics than the existing ones.

We hope our article was useful to the dear reader. If you have any questions on the topic, please ask them in the discussions. Our team is always ready to answer them. Write, share your experience, because it can help someone.

Video: how to connect an LED correctly

Content:

LED lighting is gaining popularity and is gradually replacing traditional lighting fixtures. Many types of LEDs produced by manufacturers are constantly being improved, their design is getting better every year. Power increases, cases become more optimized for use in various areas. A huge selection of colors makes it possible to create the right lighting in different rooms. Modern LEDs, due to their characteristic features, can be easily classified by type, which greatly facilitates their choice for certain purposes.

What are LEDs

The very first LEDs were used as indicators and continue to be used in this area until now. The most widely used indicator LEDs, which are elements of output wiring. They have a rectangular or round lens and are found from the simplest devices to the most sophisticated modern equipment. They are used not only for indication, but also as a backlight.

The most characteristic representatives of this group have round convex lenses, the diameter of which ranges from 3 to 10 mm. However, the low current of these LEDs makes it impossible to get a large amount of light, making their use as lighting devices impractical. Most of all they are suitable for such devices as a running line and a light board. They require negligible current and voltage and almost do not heat up.

The indicator LEDs can be white or colored according to the standard color spectrum. Some designs are available in multi-color versions. In this case, one lens is equipped with three transitions, and the lower part with four leads. Such elements are more functional, which makes it possible to create colored LED displays.

With the development of technology, more modern bright LEDs began to be used in output wiring. The luminous intensity of these elements is much higher than that of indicator LEDs, so they have become widely used for flashlights.

Surface mounting on a printed circuit board is increasingly performed using LEDs that combine indicator and lighting functions. Known as SMD - Surface Mounted Device. They are enclosed in cases with a standard size range. In terms of power, they can be compared with indicator LEDs. A large number of such LEDs can be mounted on a small PCB area. Due to this, it is possible to obtain LED lamps, and panels of almost any size.

Separately, it is worth noting a group of super-bright LEDs, widely used in outdoor advertising and car tuning. They are known as "Piranha", have a rectangular shape and improved scattering properties. Four outputs allow you to rigidly fix the element on the board or another plane. The main colors are white, red, green and blue, the dimensions are 3-7.7 mm.

At present, LEDs are most widely used indoors. They are represented by the OWL model range, which stands for Ghip On Board. These light sources can be warm and cold, white, yellow and other shades. They are similar in color to ordinary incandescent lamps, fluorescent lamps and even natural sunlight. These parameters directly depend on the characteristics of the semiconductors and the deposited phosphor. For coating, mainly blue LEDs are used, which makes it possible to obtain red, green, yellow and other colors. Light qualities are as close as possible to fluorescent lighting.

Structurally, COB LEDs consist of many crystalline semiconductors mounted on a common substrate and coated with a phosphor. Thus, it is possible to achieve high brightness due to the total luminous flux created by several light sources located very closely together. If necessary, these LEDs can be used as indicators.

During operation, these elements necessarily need heat removal, and devices with increased and high power are equipped with radiators. Otherwise, under the influence of heat, the LED crystals will be destroyed. If they are found to be partially destroyed, the entire substrate will need to be replaced. Therefore, it is recommended to take care of cooling in advance.

Today, Filament light sources are becoming more and more popular, the LEDs of which resemble a conventional filament. The light properties of this type of LEDs are noticeably superior to any OWL models. This is achieved by a large number of crystals mounted on a glass substrate. Further, the entire structure is filled with a fluorescent composition. This technology is called Chip On Glass, which means a chip on glass.

The visible solid angle is 3600, so the light output is higher than that of flat matrices. A 6W LED lamp has the same light output as a conventional 60W incandescent lamp.

LED parameters

One of the main characteristics of LEDs is the operating current. The fact is that these elements can only work at a certain current strength, which ensures normal performance. Therefore, even a slight excess of the set current value will quickly lead to the failure of the LED - it will simply burn out.

The operating current is different for each type of light source. More powerful cells require a correspondingly higher current. To adjust the required current value, special drivers are installed in each LED lamp and luminaire. If the LED is connected separately, knowledge of its technical characteristics is necessary to limit the current using the desired driver, capacitor or resistor.

An equally important parameter of LEDs is the operating voltage. Its value depends on the semiconductors themselves and other materials used in the manufacture. Thus, LEDs with different colors have different operating voltages. That is, the value of the operating voltage can be set by the color of a particular LED.

In most cases, fixtures and LED strips are powered by drivers with an output constant current of 12 V. That is, there can only be 4 LEDs in a series circuit with an operating voltage of 3 V. If you turn on an additional fifth LED, such a circuit will not work. This characteristic is also called the voltage drop, which in this case is 3 volts.

We must not forget about such a parameter as the power of the LED. Its performance is influenced by two previous characteristics - operating current and voltage drop. High current for high-power LEDs must be combined with a high-quality cooling system. For this, aluminum and copper radiators are used, as well as forced air coolers.

The power of any LED is determined by multiplying the voltage value by the current strength. When calculating the LED assembly, all elements used are taken into account. For example, the total power of an LED that includes 100 1 watt crystals will be 100 watts.

Emitted by lighting LEDs, it has a higher power compared to other sources - incandescent lamps, fluorescent and other lamps with the same or higher power. Consequently, they also have a higher luminous efficiency per watt of power of a particular LED. However, these superior qualities will vary markedly, depending on the type and workmanship of a particular item.

The angle of dispersion is of no small importance. For LEDs, it is smaller than for other lamps. To expand it, special diverging lenses are used. If it is necessary to create a narrow scattering angle, converging lenses are used to narrow the light beam. The brightness of the LED beam of light will be uneven within the limits of the scattering angle. The bright glow in the center gradually decreases as the light flux approaches the edges of this corner.

Classification

LEDs are small luminous light bulbs made from semiconductor materials. In the past, they were used as an indicator that showed that the device was on. Now developers provide innovative devices that can be used in various fields. The power of the LED allows you to use them not only as a decor, but also for lighting rooms.

Manufacturing process

LEDs are small crystals, they are grown from chemical components. Each of them is installed in a special case. By what process the crystal will be made depends on the type of LED. Work order:

Before manufacturing LED lamps or other devices, LEDs are checked for serviceability. They are tested on special stands.

Variety of LEDs

Before purchasing a product, you need to figure out what LEDs are, where they are used and how the indicated marking is deciphered. They are divided not only by the method of application, but also by installation on the circuit board. They can be indicator, lighting and laser. Types of LEDs:

Main characteristics

Before choosing the right lamp for lighting, you need to know the basic characteristics of LEDs. This will help to achieve the necessary illumination in the room. The main characteristics include operating current, power and voltage, luminous flux level, color temperature, angle and range of glow. What these characteristics depend on:

Advantages and disadvantages

LED lamps are a new and widely used technology. To determine whether such products are needed in the house, you need to know their advantages and disadvantages. Advantages of diodes:

The biggest disadvantage of LED lamps is the high cost. If we compare them with conventional lamps, then their price is 2 times higher. But it pays off quickly.

Despite the fact that the manufacturer gives a 10-year warranty, this period can be much shorter. This is influenced by the manufacturing technology and the materials used. Another disadvantage of LED lamps is that they are not suitable for simple dimmers and indicator switches. To eliminate this problem, purchase special lamps.

In order not to get lost among the variety of types and types of LEDs, we need a single standard, according to which all light emitting diodes can be divided into groups according to certain parameters. But as it turned out, there is no such standard, and each LED manufacturer classifies products at its own discretion. The reason for this approach is obvious. Optoelectronics is developing rapidly, new models of LEDs are appearing, made using more advanced technologies.

Unfortunately, it will also not work to list the main and then the secondary characteristics first. This division is highly subjective. Therefore, we will have to proceed to a detailed consideration of the issue so that the reader can clearly get acquainted with all the most common types and types of light emitting diodes.

Color classification

Current technologies make it possible to obtain an LED crystal with any color of radiation in the visible range. For this, chemical compounds of semiconductor materials of indium and gallium with different elements are used. For the purpose of unification, in addition to color, one more characteristic is indicated on the packaging with the product: the radiation wavelength. It helps to identify the shade as accurately as possible. For example, any light-emitting crystal with a wavelength from 500 to 570 nm can be attributed to a green LED. In this case, an instance with λ = 500-520 nm will have the color of a sea wave, and with λ more than 550 nm - a salad shade. Intermediate colors are obtained by the method of close arrangement of three crystals: blue, red and green, followed by control of the power of their glow. These are the so-called RGB LEDs. There are also two-color types, used mainly in indicator lighting.

A separate paragraph should mention the white types of LEDs. They have a wide emission spectrum and are formed, as a rule, on the basis of an ultraviolet LED coated with a phosphor. White LEDs have their own gradation in shades (warm, neutral, cold), which is expressed as a parameter such as .

UV and IR types of emitting diodes, although they do not work in the visible spectrum, but with their practical benefits also deserve a place in the list of LED varieties.

Power differences

Depending on the purpose, the power consumption can range from units of mW to tens of watts. The first, smallest types of LEDs are bare crystals. They are used to create COB matrices using the latest technology. The second type can conditionally include products with a power of 60 mW to 1 W (ultra-bright in a transparent case, SMD 3528 and their derivatives). The third group will include LEDs with a dissipation power of more than 1 W, requiring the use of an additional cooling system. COB matrices are considered to be the most powerful. One such module measuring 35x35 mm is capable of dissipating up to 180 watts.

The power of light

This characteristic is directly related to such parameters as power, glow angle and production technology. The smaller the angle, the greater the brightness at the measurement point. Super-bright LEDs with a beam dispersion angle of 110° have a luminous intensity of about 1000 mcd, and with an angle of 15° - a light intensity of 35,000 mcd.

In an American corporation, each generation of powerful white LEDs is listed in a separate group (S5, T6, U3 ...). Thus, the manufacturer is trying to highlight each new type of LED, which has an increased luminous flux at the same power consumption.

It should be noted that obsolete diffuse LEDs of the type with a light intensity of 0.4-6 mcd have ceased to be in demand and have been practically replaced by super-bright counterparts with a light output thousands of times greater.

Voltage classification

The voltage drop of single-chip LEDs is determined by their power and emission color and has a fixed frame. For example, a white light emitting diode might have a voltage drop of 3.3 to 3.6 volts.

Increasing the current through the crystal in order to increase the brightness could not continue indefinitely. As a result, the companies launched the production of multi-chip LEDs, which are designed for voltages of 9, 12, 18, 24, 48, 72 volts. A bright representative of this family is COB-matrices of white glow.

It is impossible not to mention the filaments, which are powered by a constant voltage of about 70 V. These specific rods are used in lamps with imitation filament.

Type of performance and purpose

If you go into details, this section will become very extensive. After all, each manufacturer produces hundreds of types of LEDs that differ in geometric dimensions. And yet there are signs by which they can be ordered. We list the main types of LEDs.

Low current. Ultra-bright two-terminal LEDs in a 3, 5 or 10 mm round transparent housing. Most often, this type of LEDs is used as indicators, advertising and information modules or traffic lights. The second sub-type of low-current LEDs are components in a rectangular or square SMD package up to 3x3.5 mm in size. SMD variants are most often used in the construction of tickers and display systems.
Powerful SMD. Assembled on a single chip without a lens, this type is used in LED lamps and consumer tapes. There are also options assembled on several crystals with a common lens. Multi-chip types of LEDs are used for industrial and decorative lighting.
COB modules. Products of white glow can reach a size of 38x38 mm in the form of squares and 50x6 mm in the form of rulers. Due to the increased luminous flux, they are in demand in the design of searchlights and street lighting lamps.
Filament LED. Made in the form of a rod about 30 mm long with many crystals on the surface. Currently, the possibilities of filament lamps are only being revealed. So far, Filament LEDs are massively used only to create 220V.
OLED. This type of thin-film organic light-emitting diodes is applied to construction of organic displays.
Emitting diodes in the IR and UV range. They are produced both in a case with leads and in SMD version. Among consumer goods, they can be seen in remote controls and lamps for drying nails.

In conclusion, it is worth noting that the above classification of LEDs is not complete and can be further supplemented by subspecies and groups. The same goes for the ever-expanding scope. But the general concept put forward by the leaders in the production of optoelectronics Nichia, Cree and Philips is described in this article in as much detail as possible.

Color

LEDs vary in the wavelength of the light emitted. Different colors (radiation of different wavelengths) are obtained by using different semiconductor materials at the base of LEDs. To date, it is possible to manufacture LEDs of any visible color (wavelengths of the visible spectrum from 400 to 760 nm), as well as infrared and ultraviolet. Special attention should be paid to white LEDs. They are obtained by applying a special phosphor to blue LEDs (less often ultraviolet). The phosphor converts blue light to white, while the efficiency of the LED naturally decreases.

Different types of white LEDs are conventionally classified according to the type of shades of white light: warm, neutral and cold. The characteristic of color in this case is the correlated color temperature, which is measured in Kelvin [K]. For warm diodes, it is 2600-3700 K, for neutral 3700-5000 K, for cold diodes - 5000-10000 K. It is important to note that, with other crystal parameters being the same, the warmer the shade of the LED, the lower its efficiency. Accordingly, the colder (the greater the proportion of blue light in the total flux), the more efficient the diode. It is believed that warm-colored LEDs are better suited for indoors, and cold-colored LEDs for street lighting.

Power

The power range of industrially produced LEDs starts from a few milliwatts and ends with tens of watts. The most powerful single-chip XML LED is produced by CREE and has a maximum operating current of 3 A, while the package dimensions are only 5x5 mm. The main scope of such diodes is street and industrial lighting, because. they have a very large overall brightness and, at a low suspension height, will create a strong glare effect.

Among lighting LEDs, one-watt LEDs with a rated current of 350 mA and three-watt LEDs with a current of 700 mA have gained the most popularity, because. they are suitable for most applications and have the largest selection of off-the-shelf power supplies. Moreover, the division of the types of LEDs by watts is rather arbitrary: as a rule, the same LED can be used in different power modes by choosing an operating current value of 350 or 700 mA (in this case, the passport value of the maximum operating current should naturally be > 700 mA). However, by increasing the current, we must take care of heat dissipation, otherwise the LED will begin to degrade quickly. It is better not to use LEDs at maximum current, but to leave a margin of at least 30% (for example, set 700 mA at I max = 1000 mA). You also need to remember that as the current increases, the light output decreases. Therefore, in cases where it is necessary to obtain maximum efficiency, it is better to reduce the current.

Many manufacturers combine LEDs into powerful matrices: crystals, usually connected in series-parallel circuits, are placed on the same base and are filled with a common phosphor layer. This technology is called Chip-On-Board or COB for short.

COB modules can have a power of up to several hundred watts and are used for lighting.

Low power LEDs (0.05 ... 0.5 W) are mainly used to illuminate the displays of various devices, including mobile devices.

This is the biggest niche in the LED market. Also, low-power LEDs can be used for lighting: in the case when it is required to obtain a uniformly luminous surface with low overall brightness, LED modules are made from tens or even hundreds of low-power LEDs. Best of all, such light sources are suitable for indoor lighting.

LEDs used for indication purposes or simply indicator ones have the smallest power. They are very diverse in shape and size, some types are shown in the figure below.