The LED driver produces more power. Types and characteristics of drivers for LED light sources. Main characteristics of converters

Each diode, in turn, has a voltage drop at different currents indicated in its description. For example, for a red 660 nm diode at a current of 600 mA it will be 2.5 V:

The number of diodes that can be connected to the driver, the total voltage drop must be within the limits of the driver's output voltage. That is, a 50W 600 mA driver with an output voltage of 60-83 V can connect from 24 to 33 red 660 nm diodes. (That is, 2.5*24 = 60, 2.5*33 = 82.5).

Another example:
We want to assemble a red + blue bicolor lamp. We have chosen a red to blue ratio of 3:1 and want to calculate which driver we need to take for 42 red and 14 blue diodes. We calculate: 42 * 2.5 + 14 * 3.5 = 154 V. This means that we will need two drivers 50 W 600 mA, each will have 21 red and 7 blue diodes, the total voltage drop on each will be 77 V, which gets into its output voltage.

Now some important clarifications:

1) You should not look for a driver with a power of more than 50 W: they are available, but they are less efficient than a similar set of drivers with a lower power. Moreover, they will get very hot, which will require you to spend additional money on more powerful cooling. In addition, drivers with a power of more than 50W are usually much more expensive, for example, a 100W driver can be more expensive than 2 50W drivers. Therefore, there is no point in chasing them. And it’s more reliable when the LED circuits are divided into sections; if something suddenly burns out, not everything will burn out, but only part of it. Therefore, it is beneficial to divide it into several drivers, rather than trying to hang everything on one. Output: 50W - best option, not more.

2) Drivers have different currents: 300 mA, 600 mA, 750 mA - these are the common ones. There are quite a lot of other options.
By and large, it will be more efficient in terms of efficiency per 1 W to use a 300 mA driver; it will also not load the LEDs much, and they will heat up less and last longer. But the main disadvantage of such drivers is that the diodes will work at half capacity, and therefore they will be required approximately twice as much as for an analogue with 600 mA.
A 750mA driver will drive the diodes to the limit, so the diodes will get very hot and will need very powerful, well designed cooling. But even despite this, they in any case degrade from overheating earlier than the average “life” of LED lamps operating, for example, at 500-600 mA current.
Therefore, we recommend using drivers with a current of 600 mA. They turn out to be the most optimal solution in terms of the price-efficiency-service life ratio.

3) The power of the diodes is indicated as nominal, that is, the maximum possible. But they are never powered to the maximum (why - see point 2). It is very simple to calculate the real power of the diode: you need to multiply the current of the driver used by the voltage drop of the diode. For example, when connecting a 600 mA driver to a 660 nm red diode, we get the actual voltage on the diode: 0.6(A) * 2.5(V) = 1.5 W.

One of the conditions for reliable operation of LEDs is a high-quality, stable supply of direct current at a given voltage.

Led-driver is just designed for this.

Let's consider the main purpose and principle of its operation, what main parameters it is characterized by, what types exist, how it differs from a standard power supply, how to choose the right one and what are the basic diagrams for connecting it.

Led-driver is a stabilizing module. Without it, none of the currently produced LED elements can work - from the weakest to the most powerful. It must be strictly selected for the load of the assembled circuit, especially when the luminaires have a serial connection. In this case, the voltage drop in each specific led light source can vary (as it depends on the factory assembly parameters), while the current strength should remain the same for all of them.

The role of the led-driver simply cannot be overestimated. After all, with the slightest increase in power supply parameters, the semiconductor crystal instantly heats up and burns out. On the other hand, when the network characteristics drop, the light output suffers and the aperture ratio declared by the manufacturer decreases. That's why it's so important to choose the right driver for LEDs.

Principle of operation

The main purpose of the led-driver is to maintain the stability of the output current. Drivers for led elements produced today are mostly assembled on the principle of operation of pulse-width converters. They include a pulse transformer and current-stabilizing microcircuits. Such devices are designed to be powered from a household network with a voltage of 220 volts, are characterized by a high efficiency index and have a special fuse against overload and short circuit.

There are also linear type LED-drivers. The principle of its operation is based on stabilizing the current as it passes through a transistor with a p-channel. Unlike the modification described above, it is a cheaper, simpler and less efficient analogue. During operation, such drivers can become very hot, and therefore are not used for circuits with powerful LED elements.

Main characteristics

Among the main characteristics of the led-driver, the following three are of particular importance to its operating parameters:

1. Output voltage.
2. Rated current.
3. Power.

The first factor is influenced by the voltage drop of the ice element itself, as well as the method of its connection. If a parallel circuit is used, then the voltage on all LEDs will be the same. The result will be different when using a sequential circuit. Here the value of this parameter should be equal to the total voltage drop of all elements of the chain.

The value of the rated current of the led-driver is directly dependent on the brightness and power of the led lamps. The driver must supply a current of such strength that their luminous intensity is equal to that declared by the manufacturer.

The power or output load of the led-driver must not be lower than the total value of the same parameter for all participants in the circuit. For example, if there are 10 LEDs of 2 W in a circuit, then their sum will be equal to 20 W. In this case, a buffer of 20-30% (power reserve) must be added to the calculated load. In this case it will be: 20 W + (20 x 0.3) 6 W = 26 W.

Important! When calculating the power of a led-driver, it is also necessary to take into account the color of the led element, since crystals of different color rendering with equal brightness and current strength have different voltage drops, and therefore power. For example, two 359 mA LEDs, red and green, draw 1.9–2.4 V and 3.3–3.9 V, respectively, and therefore have 0.75 and 1.25 W, respectively.

Types of LED Drivers

There are two main types of led-driver - pulse and linear type. The difference between them is the principle of stabilization electric current, which is expressed in the main characteristics, areas of application and service life. Let's look at them in more detail.

Linear stabilizer

A linear led-driver performs the function of a simple automatic resistor. At the slightest change in current strength, it instantly restores its set value at the output. The role of such a device is performed by a transistor. Regardless of how the characteristics of the external power supply network change, its internal value remains constant.

Read also The design and principle of operation of a diode with direct and reverse connection

The advantage of such a system is its simplicity of design, low cost and stability. However, the main disadvantage of a linear stabilizer is the loss of a share of power due to its transition to thermal energy. In this case, there is a direct relationship between the absolute value of the incoming voltage and the flow rate. Therefore, linear type led-driver is suitable for low-power LEDs. It is not used on LED elements with high current parameters, since the drivers themselves will consume more energy than the semiconductor crystals themselves.

Pulse stabilization

A pulse led-driver is a pulse capacitor with a automatic device turning on/off electric current. As soon as the voltage in it reaches the operating value and the LED bus or lamp lights up, the switch is triggered and the current stops - to avoid further potential growth and to avoid burnout of the crystal in the lamp.

Subsequently, as the potential is gradually consumed, a current is turned on in the storage capacitor to recharge it so that the lantern does not fade. The recharge time and the shutdown period may vary depending on the voltage in the external network. The role of such a regulator-switch, operating in an automatically programmed mode, is performed by a pulse led-driver.

Its coefficient useful action close to 100%. That’s why it is used even on very powerful spotlights. At the same time, the LED-driver in its circuit is so efficient that its housing does not even require special radiators to remove heat. Among their main disadvantages are the complexity of the device and the high price. On the other hand, a number of advantages such as high performance, small dimensions and weight and high quality the provided current stability easily levels them out.

What are the differences between a driver for LEDs and a power supply for LED strip?

The question is whether led-drivers differ from each other for LED lamp and ribbons, excites all those who want to make lighting with their own hands from Supplies. You can answer this only by first understanding what an led strip is, what elements it consists of, and how it all works.

A regular ice strip is a set of LEDs connected to each other in one or several rows according to an electrical circuit and mounted on a special elastic substrate. In turn, inside they are divided into groups of 3 or 6 crystals. All of them are connected through a current limiting resistor in a series chain. In this case, the groups have a parallel connection to each other.

The operating voltage for ice strips is 12 or 24 volts. In this case, the entire tape is divided into sections. Each of them has its own resistor - to limit and stabilize the current. Thus, the task of the power supply is to convert the output voltage strictly to 12 or 24 volts - no more and no less. This is precisely the difference from a regular led-driver, which can be designed for any other operating voltage (as a rule, this is a range, for example, from 8 to 13 volts). At the same time, the ice strip driver does not monitor the parameters of the output current at all - this is the task of the resistors in each group of LEDs.

How to choose

The correct selection of led-driver for powering an LED should take into account the following parameters:

• Input voltage value.
• The magnitude of the output voltage.
• Output current.
• Output power.
• Moisture and dust protection.

The basic principle of choosing the right driver for an LED is to begin calculating its characteristics only after the number of light sources and their main parameters (primarily power) in the planned circuit are known exactly. In addition, it is necessary to know in advance the operating conditions of electrical equipment - indoors or outdoors, what are the parameters of temperature and humidity fluctuations, as well as the effect of precipitation.

Important! When choosing a led-driver, you need to know exactly from which source it will be powered. This could be a 220-volt household network, or a car battery, or a diesel power plant, etc. The voltage range from them must fit within the operating input voltage of the ice driver. You also need to know in advance the nature of the incoming current - whether it is constant or alternating.

Next, you need to correctly calculate the output parameters for the led-driver. First of all there is tension. It is calculated as follows: it is necessary to sum up the value of all ice elements in the chain. For example, if there are 5 diodes of 3 volts in the circuit, the total will be 5x3 = 15 volts. It should be taken into account that the connection of the lamps will be serial. There is one more quantity in the input characteristics - current strength. It will be the same for all lamps.

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In recent years, it has become increasingly popular. This is due to the fact that the LEDs used in the lamps, also called light-emitting diodes (LEDs), are quite bright, economical and durable. Using LED elements, interesting and original lighting effects are created that can be used in a wide variety of interiors. However, such lighting devices are very demanding on the parameters of electrical networks, especially on the current value. Therefore for normal operation LED drivers must be included in the lighting circuit. In this article we will try to figure out what LED drivers are, what are their main characteristics, how not to make a mistake when choosing, and whether it is possible to make one yourself.

Without such a miniature device, the LEDs will not work

Since LEDs are current devices, they are accordingly very sensitive to this parameter. For normal lighting operation, a stabilized current with a nominal value must pass through the LED element. For these purposes, a driver for LED lamps was created.

Some readers, when they see the word driver, will be at a loss, since we are all accustomed to the fact that this term refers to some software that allows you to manage programs and devices. Translated from in English driver means: driver, driver, leash, mast, control program and more than 10 more values, but they are all united by one function - control. This is the case with drivers for, only they control the current. So, we’ve sorted out the term, now let’s get to the point.

LED driver – electronic device, at the output of which, after stabilization, a direct current of the required magnitude is generated, ensuring normal operation of the LED elements. In this case, it is the current, not the voltage, that is stabilized. Devices that stabilize the output voltage are called, which are also used to power LED lighting elements.

As we already understood, the main parameter of the driver for LEDs is the output current, which the device can provide for a long time when the load is turned on. For normal and stable glow of LED elements, it is required that a current flow through the LED, the value of which must coincide with the values ​​​​specified in the technical data sheet of the semiconductor.

Where are LED drivers used?

As a rule, LED drivers are designed to operate with voltages of 10, 12, 24, 220 V and a constant current of 350 mA, 700 mA and 1 A. Current stabilizers for LEDs are produced mainly for specific products, but there are also universal devices compatible with LED elements from leading manufacturers.

LED drivers in AC networks are mainly used for:

In electrical circuits with direct current, stabilizers are needed for the normal operation of on-board lighting and car headlights, portable lights, etc.

Current stabilizers are adapted to work with control systems and photocell sensors, and due to their compactness can be easily installed in distribution boxes. Also, using drivers, you can easily change the brightness and color of the LED elements, reducing the current through digital control.

How do stabilizing devices for LEDs work?

The principle of operation of the converter for and tapes is to maintain a given current value regardless of the output voltage. This is the difference between a power supply and an LED driver.

If we look at the diagram presented above, we will see that the current, thanks to resistor R1, is stabilized, and capacitor C1 sets the required frequency. Next, the diode bridge is switched on, as a result of which a stabilized current is supplied to the LEDs.

Device Features You Need to Pay Attention to

When choosing an LED driver for LED lamps, it is necessary to take into account the main parameters, namely: current, output voltage and power consumed by the connected load.

The output voltage of the current stabilizer depends on the following factors:

• number of LED elements;
• LED voltage drop;
• connection method.

The current at the output of the device is determined by the power and. The power of the load affects the current it consumes depending on the required glow intensity. It is the stabilizer that provides the LEDs with the required current.

The power of an LED lamp depends directly on:

• power of each LED element;
• total number of LEDs;
• colors.

The power consumed by the load can be calculated using the following formula:

P N = PLED × N , Where

• P N – total load power;
• P LED – power of an individual LED;
• N – number of LED elements connected to the load.

The maximum power of the current stabilizer should not be less than PH. For normal operation of the LED driver, it is recommended to provide a power reserve of at least 20÷30%.

In addition to the power and number of LEDs, the power of the load connected to the driver also depends on the color of the LED elements. The fact is that LEDs of different colors have different voltage drops at the same current value. So, for example, for a red CREE XP-E LED, the voltage drop at a current of 350 mA is 1.9÷2.4 V, and the average power consumption will be about 750 mW. For a green LED element at the same current, the voltage drop will be 3.3÷3.9 V, and the average power will be almost 1.25 W. Accordingly, a current stabilizer designed for a power of 10 W can power 12÷13 red LEDs or 7-8 green LEDs.

Types of stabilizers by device type

Current stabilizers for light-emitting diodes are divided according to the type of device into pulsed and linear.

For a linear driver, the output is a current generator that provides smooth stabilization of the output current when the input voltage is unstable, without creating high-frequency electromagnetic interference. Such devices have simple design and low cost, but not very high efficiency (up to 80%) narrows the scope of their use to low-power LED elements and strips.

Pulse-type devices allow you to create a series of high-frequency current pulses at the output. Such drivers operate on the principle of pulse width modulation (PWM), that is, the average output current is determined by the ratio of the pulse width to their frequency. Such devices are more in demand due to their compactness and higher efficiency, which is about 95%. However, compared to linear PWM drivers, stabilizers have a higher level of electromagnetic interference.

How to choose a driver for LEDs

It should be immediately noted that a resistor cannot be a full replacement for a driver, since it is not able to protect the LEDs from power surges and impulse noise. Also, using a linear current source would not be the best option due to its low efficiency, which limits the capabilities of the stabilizer.

When choosing an LED driver for LEDs, you should adhere to the following basic recommendations:

• It is best to purchase a current stabilizer at the same time as the load;
• take into account the voltage drop across the LEDs;
• a high current rating reduces the efficiency of the LED and causes it to overheat;
• take into account the power of the load connected to the driver.

It is also necessary to pay attention that the stabilizer case indicates its power, operating ranges of input and output voltage, rated stabilized current and the degree of moisture and dust protection of the device.

Recommendation! How powerful and high quality will the driver be for LED strip or LED, the choice is, of course, up to you. However, it should be remembered that for the normal operation of the entire lighting system being created, it is best to buy a proprietary converter, especially if we're talking about O LED spotlights and other powerful lighting devices.

Connecting current converters for LEDs: driver circuit for a 220 V LED lamp

Most manufacturers produce drivers on integrated circuits (ICs), which allow them to be powered from a reduced voltage. All converters for LED lighting that currently exist are divided into simple ones, created on the basis of 1÷3 transistors, and more complex ones, made using PWM microcircuits.

The above is an IC based driver circuit, but as we mentioned, there are connection methods using resistors and transistors. In fact, there are many connection options and it is simply impossible to consider them all in detail in one review. On the Internet you can find almost any scheme suitable for your situation.

How to calculate a current stabilizer for LED lighting

To determine the output voltage of the converter, it is necessary to calculate the ratio of power and current. So, for example, with a power of 3 W and a current of 0.3 A, the maximum output voltage will be 10 V.Next, you need to decide on the connection method, parallel or serial, as well as the number of LEDs. The fact is that the rated power and voltage at the driver output depend on this. After calculating all these parameters, you can select the appropriate stabilizer.

It is worth noting that converters designed for a certain number of LED elements have protection against emergency situations. This type of device is characterized by incorrect operation when connecting a smaller number of LEDs - flickering is observed or does not work at all.

Dimmable driver for LED elements - what is it?

The latest models of converters for LEDs are adapted to work with dimmers of semiconductor crystals -. The use of these devices allows for more efficient use of electricity and increases the life of the LED element.

Dimmable converters come in two types. Some are included in the circuit between the stabilizer and LED lighting elements and operate via PWM control. Converters of this type are used to work with LED strips, ticker tape, etc.

In the second option, the dimmer is installed at the gap between the power source and the stabilizer, and the operating principle consists of both controlling the parameters of the current passing through the LEDs and using pulse-width modulation.

Features of Chinese current converters for LEDs

The high demand for drivers for LED lighting has led to their mass production in the Asian region, particularly in China. And this country is famous not only for high-quality electronics, but also for the mass production of all kinds of counterfeits. Chinese-made LED drivers are pulsed current converters, usually designed for 350÷700 mA and in a packageless design.

The advantages of Chinese current converters are only low cost and the presence of galvanic isolation, but there are still more disadvantages and they consist of:

• high level of radio interference;
• unreliability caused by cheap circuit solutions;
• vulnerability to network fluctuations and overheating;
• high level of ripple at the output of the stabilizer;
• short service life.

Typically, Chinese-made components operate at the limit of their capabilities, without any reserve. Therefore, if you want to create a reliably operating lighting system, it is best to buy a converter for LEDs from a well-known, trusted manufacturer.

Service life of current converters

Like any electronic device, the driver for an LED current source has a certain service life, which depends on the following factors:

• network voltage stability;
• temperature changes;
• humidity level.

Well-known manufacturers guarantee their products for an average of 30,000 hours of operation. The cheapest, simplest stabilizers are designed to operate for 20,000 hours, average quality - 20,000 hours, and Japanese ones - up to 70,000 hours.

LED driver circuit based on RT 4115

Due to the emergence of a large number of LED elements with a power of 1–3 W and a low price, most people prefer to use them to make home and car lighting. However, this requires a driver that will stabilize the current to the nominal value.

For correct operation of the converter, it is recommended to use tantalum capacitors. If you do not install a capacitor on the power supply, then integrated circuit(IC) will simply fail when the device is connected to the network. Above is a driver circuit for an LED on the PT4115 IC.

How to make your own LED driver

Using ready-made microcircuits, even a novice radio amateur can assemble a converter for LEDs of various powers. This requires the ability to read electrical diagrams and experience with a soldering iron.

Collect current stabilizer for 3-watt stabilizers, you can use a chip from the Chinese manufacturer PowTech - PT4115. This IC can be used for LED elements with a power of more than 1 W and consists of control units with quite powerful transistor at the exit. The converter, based on PT4115, has high efficiency and a minimum set of components.

As you can see, if you have experience, knowledge and desire, you can assemble an LED driver according to almost any scheme. Now let's consider step by step instructions creating a simple current converter for 3 LED elements with a power of 1 W each, from a charger for mobile phone. By the way, this will help you better understand the operation of the device and later move on to more complex circuits designed for a larger number of LEDs and strips.

Instructions for assembling a driver for LEDs

Image	Description of the stage
	To assemble the stabilizer, you will not need an old mobile phone charger. We took them from Samsung, they are so reliable. Charger with parameters 5 V and 700 mA, carefully disassemble.
	We also need a 10 kOhm variable (tuning) resistor, 3 1 W LEDs and a cord with a plug.
	This is what the disassembled charger looks like, which we will redo.
	We unsolder the 5 kOhm output resistor and put a “tuner” in its place.
	Next, we find the output to the load and, having determined the polarity, solder the LEDs, pre-assembled in series.
	We unsolder the old contacts from the cord and connect the wire and plug in their place. Before checking the functionality of the driver for LEDs, you need to make sure that the connections are correct, that they are strong, and that nothing creates a short circuit. Only after this can you start testing.
	We start adjusting with a trimming resistor until the LEDs start to glow.
	As you can see, the LED elements are lit.
	Using a tester, we check the parameters we need: output voltage, current and power. If necessary, adjust with a resistor.
	That's all! The LEDs burn normally, nothing sparks or smokes anywhere, which means the conversion was successful, for which we congratulate you.

As you can see, making a simple driver for LEDs is very simple. Of course, experienced radio amateurs may not be interested in this scheme, but for a beginner it is perfect for practice.

LEDs occupy the leading position among the most effective sources of artificial light today. This is largely due to the high-quality power sources for them. When working in conjunction with a properly selected driver, the LED will maintain stable light brightness for a long time, and the service life of the LED will be very, very long, measured in tens of thousands of hours.

Thus, a correctly selected driver for LEDs is the key to long and reliable operation of the light source. And in this article we will try to cover the topic of how to choose the right driver for an LED, what to look for, and what they generally are.

An LED driver is a stabilized constant voltage or constant current power supply. In general, initially, an LED driver is a , but today even constant voltage sources for LEDs are called LED drivers. That is, we can say that the main condition is stable DC power characteristics.

An electronic device (essentially a stabilized pulse converter) is selected for the required load, be it a set of individual LEDs assembled in a series chain, or a parallel set of such chains, or maybe a strip or even one powerful LED.

A stabilized constant voltage power supply is well suited for LED strips, or for powering a set of several high-power LEDs connected one at a time in parallel - that is, when the rated voltage of the LED load is precisely known, and it is only necessary to select a power supply for the rated voltage at the corresponding maximum power .

Usually this does not cause problems, for example: 10 LEDs at 12 volts, 10 watts each, will require a 100 watt 12 volt power supply, rated for a maximum current of 8.3 amperes. All that remains is to adjust the output voltage using the adjusting resistor on the side, and you’re done.

For more complex LED assemblies, especially when several LEDs are connected in series, you need not just a power supply with a stabilized output voltage, but a full-fledged LED driver - an electronic device with a stabilized output current. Here, current is the main parameter, and the supply voltage of the LED assembly can automatically vary within certain limits.

For an even glow of the LED assembly, it is necessary to ensure rated current through all the crystals, however, the voltage drop across the crystals may differ for different LEDs (since the current-voltage characteristics of each LED in the assembly are slightly different), so the voltage will not be the same on each LED, but the current should be the same.

LED drivers are produced mainly for power supply from a 220 volt network or from a 12 volt vehicle on-board network. The driver output parameters are specified in the form of voltage range and rated current.

For example, a driver with an output of 40-50 volts, 600 mA will allow you to connect four 12-volt LEDs with a power of 5-7 watts in series. Each LED will drop approximately 12 volts, the current through the series chain will be exactly 600 mA, while the voltage of 48 volts falls within the operating range of the driver.

A driver for LEDs with stabilized current is a universal power supply for LED assemblies, and its efficiency is quite high and here's why.

The power of the LED assembly is an important criterion, but what determines this load power? If the current were not stabilized, then a significant part of the power would be dissipated on the equalizing resistors of the assembly, that is, the efficiency would be low. But with a current-stabilized driver, equalizing resistors are not needed, and the resulting efficiency of the light source will be very high.

Drivers from different manufacturers differ in output power, protection class and used element base. As a rule, it is based on current output stabilization and protection against short circuit and overload.

Powered by 220 volt AC or 12 volt DC. The simplest compact drivers with low-voltage power supply can be implemented on a single universal chip, but their reliability, due to simplification, is lower. Nevertheless, such solutions are popular in auto tuning.

When choosing a driver for LEDs, you should understand that the use of resistors does not protect against interference, nor does the use of simplified circuits with quenching capacitors. Any voltage surges pass through resistors and capacitors, and the nonlinear I-V characteristic of the LED will certainly be reflected in the form of a current surge through the crystal, and this is harmful for the semiconductor. Linear stabilizers are also not the best option in terms of immunity to interference, and the efficiency of such solutions is lower.

It is best if the exact number, power, and switching circuit of the LEDs are known in advance, and all LEDs in the assembly will be the same model and from the same batch. Then select the driver.

The range of input voltages, output voltages, and rated current must be indicated on the case. Based on these parameters, a driver is selected. Pay attention to the protection class of the housing.

For research tasks, for example, packageless LED drivers are suitable; such models are widely represented on the market today. If you need to place the product in a housing, the user can make the housing independently.

Andrey Povny

LEDs, which have seriously displaced all other light sources in recent years, can be found everywhere today. They are used in apartments and offices, illuminate streets, decorate buildings and interiors. But for proper operation of a semiconductor light source, a high-quality and reliable driver for LEDs is required. Today we will talk about this extremely important unit and figure out why this driver is so necessary, how it works, and even try to make a led driver with our own hands.

What is a driver and why is it needed?

If you look into the English-Russian dictionary, you can find out that a driver is literally a “driver” (driver - driver, English). Where does this strange name come from and what does he drive? In order to understand this, let’s digress a little and talk about LEDs.

A light-emitting diode (LED) is a semiconductor device capable of emitting light under the influence of voltage applied to it. Moreover, for proper operation of the semiconductor, the voltage that provides the optimal current through the crystal must be constant and strictly stabilized. This is especially true for powerful LEDs, which are extremely critical of all kinds of drops and surges in the supply current. As soon as the diode's power supply decreases slightly, the current will drop and, as a result, the light output will decrease. At the slightest excess of the normal current value, the semiconductor instantly overheats and burns out.

The main purpose of the driver is to provide the light-emitting diode with the current necessary for its normal operation. Thus, an LED driver is, in fact, a power supply for LEDs, their “driver”, which ensures long-term and high-quality operation of the semiconductor illuminator.

Expert opinion

Alexey Bartosh

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You will not find a single lighting device that contains a powerful LED that does not have a driver. Therefore, it is so important to understand what drivers are, how they work and what characteristics they should have.

Types of LED Drivers

All drivers for LEDs can be divided according to the principle of current stabilization. Today there are two such principles:

1. Linear.
2. Pulse.

Linear stabilizer

Suppose we have a powerful LED at our disposal that needs to be lit. Let's collect the simplest scheme:

Diagram explaining the linear principle of current regulation

We set resistor R, which acts as a limiter, to the desired current value - the LED lights up. If the supply voltage has changed (for example, the battery is low), turn the resistor slider and restore the required current. If it has increased, then we reduce the current in the same way. This is exactly what the simplest linear stabilizer does: it monitors the current through the LED and, if necessary, “turns the knob” of the resistor. Only he does this very quickly, managing to react to the slightest deviation of the current from the specified value. Of course, the driver does not have any knob; its role is played by a transistor, but the essence of the explanation does not change.

What is the disadvantage of a linear current stabilizer circuit? The fact is that current also flows through the regulating element and uselessly dissipates power, which simply heats the air. Moreover, the higher the input voltage, the higher the losses. For LEDs with a small operating current, this circuit is suitable and successfully used, but it is more expensive to power powerful semiconductors with a linear driver: the drivers can consume more energy than the illuminator itself.

The advantages of such a power supply include the relative simplicity of the circuit design and the low cost of the driver, combined with high reliability.

Linear driver for powering an LED in a flashlight

Pulse stabilization

We have the same LED, but we’ll assemble a slightly different power circuit:

A diagram explaining the operating principle of a pulse-width stabilizer

Now, instead of a resistor, we have a KH button and a storage capacitor C has been added. We apply voltage to the circuit and press the button. The capacitor begins to charge, and when the operating voltage is reached, the LED lights up. If you continue to hold the button pressed, the current will exceed the permissible value and the semiconductor will burn out. Let's release the button. The capacitor continues to power the LED and gradually discharges. As soon as the current drops below the permissible value for the LED, press the button again, energizing the capacitor.

We sit like this and periodically press the button, maintaining the normal operation of the LED. The higher the supply voltage, the shorter the presses will be. The lower the voltage, the longer the button will have to be pressed. This is the principle of pulse width modulation. The driver monitors the current through the LED and controls a switch assembled on a transistor or thyristor. He does this very quickly (tens and even hundreds of thousands of clicks per second).

At first glance, the work is tedious and difficult, but not for electronic circuit. But the efficiency of a pulse stabilizer can reach 95%. Even when powered, energy losses are minimal, and key driver elements do not require powerful heat sinks. Certainly, pulse stabilizers somewhat more complex in design and more expensive, but all this pays off with high performance, exceptional quality of current stabilization and excellent weight and size characteristics.

This pulse driver is capable of delivering current up to 3 A without any heatsinks.

How to choose a driver for LEDs

Having understood the operating principle of led drivers, all that remains is to learn how to choose them correctly. If you haven't forgotten the basics of electrical engineering you learned in school, then this is a simple matter. We list the main characteristics of the converter for LEDs that will be involved in the selection:

• input voltage;
• output voltage;
• output current;
• output power;
• degree of protection from the environment.

First of all, you need to decide from what source your LED lamp. This can be a 220 V network, a car’s on-board network, or any other source of both alternating and direct current. The first requirement: the voltage that you will use must be within the range specified in the driver passport in the “input voltage” column. In addition to the magnitude, you need to take into account the type of current: direct or alternating. After all, in a socket, for example, the current is alternating, but in a car it is constant. The first is usually denoted by the abbreviation AC, the second DC. Almost always this information can be seen on the body of the device itself.

This driver is designed to operate on AC power from 100 to 265 V

Next we move on to the output parameters. Let's assume you have three LEDs with an operating voltage of 3.3 V and a current of 300 mA each (indicated in the accompanying documentation). You decided to do table lamp, the diode connection diagram is sequential. We add up the operating voltages of all semiconductors, and we get the voltage drop across the entire chain: 3.3 * 3 = 9.9 V. The current with this connection remains the same - 300 mA. This means you need a driver with an output voltage of 9.9 V, providing current regulation at 300 mA.

Expert opinion

Alexey Bartosh

Specialist in repair and maintenance of electrical equipment and industrial electronics.

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Important! All semiconductors operating from the same driver must be of the same type and preferably from the same batch. Otherwise, a scatter in the parameters of the LEDs is inevitable, as a result of which one of them will shine at full intensity, and the second will quickly burn out.

Of course, it will not be possible to find a device for this particular voltage, but this is not necessary. All drivers are designed not for a specific voltage, but for a certain range. Your task is to fit your value into this range. But the output current must exactly correspond to 300 mA. In extreme cases, it can be slightly less (the lamp will not shine so brightly), but never more. Otherwise, your homemade product will burn out immediately or in a month.

Go ahead. We find out what power driver we need. This parameter should at least match the power consumption of our future lamp, and it is better to exceed this value by 10-20%. How to calculate the power of our “garland” of three LEDs? Remember: the electrical power of a load is the current flowing through it multiplied by the applied voltage. We take a calculator and multiply the total operating voltage of all LEDs by current, having first converted the latter to amperes: 9.9 * 0.3 = 2.97 W.

Finishing touch. Design. The device can be either in a housing or without it. The first one, naturally, is afraid of dust and moisture, and in terms of electrical safety it is not the best option. If you decide to build a driver into a lamp whose housing is good protection from the environment, then it will do. But if the lamp body has a bunch of ventilation holes (the LEDs need to be cooled), and the device itself will be in the garage, then it is better to choose a power source in its own housing.

So, we need an LED driver with the following characteristics:

• supply voltage – 220 V AC;
• output voltage – 9.9 V;
• output current – ​​300 mA;
• output power – at least 3 W;
• The housing is dust and waterproof.

Let's go to the store and take a look. Here he is:

Driver for powering LEDs

And not just suitable, but ideally suited to the needs. A slightly reduced output current will extend the life of the LEDs, but this will have absolutely no effect on the brightness of their glow. Power consumption will drop to 2.7 W - there will be a reserve of driver power.

Expert opinion

Alexey Bartosh

Specialist in repair and maintenance of electrical equipment and industrial electronics.

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If you have a very large number of LEDs, then when you turn them on in series total voltage may exceed the maximum possible for existing drivers. In this case, refer to the section Diagram for connecting the driver to the LEDs, which is located at the end of this article.

What are the differences between a driver for LEDs and a power supply for LED strip?

There is an opinion that power supplies are something different than a regular LED driver. Let’s try to clarify this issue, and at the same time learn how to choose the right driver for the LED strip. An LED strip is a flexible substrate on which the same LEDs are located. They can stand in 2, 3, 4 rows, it’s not that important. It is more important to understand how they are connected to each other.

All semiconductors on the tape are divided into groups of 3 LEDs, connected in series through a current-limiting resistor. All groups, in turn, are connected in parallel:

Electrical diagram one section (left) and the entire LED strip

The tape is sold in reels, usually 5 m long, and is designed for an operating voltage of 12 or 24 V. In the latter case, each group will have not 3, but 6 LEDs. Let's assume you bought a 12 V tape with a specific power consumption of 14 W/m. Thus, the total power consumed by the entire bobbin will be 14 * 5 = 70 W. If you don't need such a long one, you can cut off the unnecessary part, provided that you cut it between sections. For example, you cut off half. What characteristics will change? Only power consumption: it will be halved.

Expert opinion

Alexey Bartosh

Specialist in repair and maintenance of electrical equipment and industrial electronics.

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Important! Do not forget that you can cut the LED strip only between sections of 3 LEDs (for 24-volt there will be 6), which are clearly visible. In the picture below I have marked them with arrows.

The places where sections separate are clearly visible and are even marked with scissor icons

Is it necessary to limit and stabilize the current through a regular LED? Of course, otherwise it will burn. But we completely forgot about the resistor installed in each section of the tape. It serves to limit the current and is selected in such a way that when exactly 12 volts are supplied to the section, the current through the LEDs will be optimal. The task of the LED strip driver is to keep the supply voltage strictly at 12 V. The rest is taken care of by the current-limiting resistor.

Thus, the main difference between the LED strip power supply and a conventional LED driver is a clearly fixed output voltage of 12 or 24 V. Here it is no longer possible to use a conventional driver with an output voltage, say, from 9 to 14 V.

The remaining criteria for choosing a power supply for an LED strip are as follows:

• input voltage. The selection method is the same as for a conventional driver: the device must be designed for the input voltage and the type of current with which you will power the LED strip;
• output power. The power of the power supply must be at least 10% higher than the power of the tape. At the same time, you should not take too much stock: the efficiency of the entire structure decreases;
• environmental protection class. The technique is the same as for the LED driver (see above): dust and moisture should not get into the device.

A driver for an LED strip is nothing more than a high-quality, but ordinary voltage stabilizer. It produces a strictly fixed voltage, but does not monitor the output current at all. If you wish and for experimentation, you can use, for example, a power supply from a PC (12 V bus) instead. The brightness and durability of the tape will not be affected by this.

Diagram of connecting the driver to the LEDs

Connecting the driver to the LEDs is simple, anyone can do it. All markings are applied to its body. You apply input voltage to the input wires (INPUT), and connect a line of LEDs to the output wires (OUTPUT). The only thing is that it is necessary to maintain polarity, and I will dwell on this in more detail.

Input Polarity (INPUT)

If the voltage supplying the driver is constant, then the pin marked “+” must be connected to the positive pole of the power source. If the voltage is alternating, then pay attention to the markings of the input wires. The following options are possible:

1. Marking “L” and “N”: a phase must be applied to the “L” terminal (located using an indicator screwdriver), and a zero must be applied to the “N” terminal.
2. Marking “~”, “AC” or absent: polarity does not need to be observed.

Output polarity (OUTPUT)

Polarity is always observed here! The positive wire is connected to the anode of the first LED, the negative wire to the cathode of the last. The LEDs themselves are connected to each other: the anode of the next one to the cathode of the previous one.

Diagram of connecting the driver to a garland of three LEDs connected in series

If you have a lot of LEDs (say, 12 pieces), then they will have to be divided into several identical groups, and these groups will have to be connected in parallel. Please note that the total power consumed by the luminaire will be the sum of the powers of all groups, and the operating voltage will correspond to the voltage of one group.