The design and principle of operation of drivers for LED lamps

Драйвер для светодиодных лампПодключение

Drivers are special devices that ensure stable operation of LED lamps. Without them, diodes are unstable and quickly fail. We will learn how drivers are arranged and how they function.

Why LED driver?

LEDs are much more energy efficient and last longer than incandescent bulbs. They can work for years and consume several times less electricity than conventional light bulbs, with a stable power supply, for which the driver is responsible.
Driver for LED lampsLEDs are very sensitive to the power supplied to their inputs. They are not afraid of lower values, but increased voltages and currents can not only significantly reduce the resource of semiconductors, but also disable them. The task of the driver is to provide the LEDs with a stable current. Driver for LED lamps – power supply. It is an electronic circuit, the output of which is a constant current of a given value.

In order for LED elements to work for a long time and efficiently, burn brightly and without flickering, a current of such a value that is indicated in the technical data sheet of the semiconductor element must flow through the LEDs.

LED drivers offered by manufacturers are designed for voltages of 10, 12, 24, 220 V and direct currents of 350 mA, 700 mA, 1 A. Usually, drivers are made for specific fixtures, but there are also universal devices on sale that fit most LED- items from well-known brands. Current stabilizers are used in:

  • street and home lighting systems;
  • desktop office lamps;
  • LED strips and decorative lighting.

Drivers change the brightness and color of the LEDs. This is done using the knobs or the remote control. An LED lamp without a driver is unstable and runs the risk of quickly failing.

Principle of operation

A voltage is applied to the input of the LED driver, which can vary. The current passes through the resistances R1 and R3, acquiring the desired value, and the capacitor C1 sets its frequency. Alternating current, acquiring the set parameters, enters the diode bridge. Passing through this rectifier, the current is converted from alternating to direct. Further, its parameters are adjusted by resistors R2 and R4 and capacitor C2. In this way, the maximum accuracy of the output current parameters is achieved. Electrical circuit diagram of the device:
Scheme

Types of drivers according to the principle of operation

All drivers for LEDs are divided into linear and pulsed. Each group has its pros, cons and recommendations for use. Comparison of linear and pulse current converter:

Type ofprosMinusesApplication
LinearDoesn’t interfereLess than 80% efficiency, heats upLow power LED lights, strips and flashlights
PulseHigh efficiency – 95%Creates electromagnetic pickupsStreet lighting and household

Linear

Based on the linear circuit, the simplest drivers for the LED lamp are created. As a stabilization element, a limiting resistor with a variable resistance is used. In an industrial driver, the “engine” of the resistor is controlled not by a person, but by electronics. If the voltage rises to critical values, the current also begins to grow, and when it reaches an unacceptable value, the LED overheats and is subsequently destroyed. In more complex circuits, transistors are used to regulate the current. The disadvantage of the linear circuit is large power losses, since with increasing voltage, its useless dissipation increases. A similar drawback is permissible except for low-power lamps. For multi-watt LEDs, such schemes are not suitable. Advantages of a linear stabilization scheme:

  • simple design;
  • low cost;
  • sufficient reliability (at low load power).

Linear Stabilizer:
Linear stabilizer

Pulse

The second option is impulse stabilization. After turning on the KH button, the capacitor C is charged. After opening the contacts of the button, it begins to discharge, giving electricity to the semiconductor element. The simplest switching regulator:
The simplest stabilizerWhile the capacitor gives off energy, the diode emits light. The higher the input voltage, the shorter the charging time. Pressing and releasing the button maintains the glow. This principle of operation is called pulse-width modulation. Dozens and even thousands of operations occur per second.

Types of drivers by design type

Drivers for LED elements are a small electronic circuit assembled from resistors, capacitors and semiconductor diodes placed on the board. Devices that stabilize the current for LEDs are available in 2 versions:

  • In the hull. This is the most common option. The cost of such a device is higher. Its main advantage is the protection of structural elements from moisture and dust.
  • Without body. Their use is justified only for hidden installation. They are cheaper than case analogs.

According to the design, converters are divided into three groups.

Electronic

In an electronic converter, a transistor is responsible for correcting the current. Its task is to unload the control microcircuit. To smooth out the ripple as much as possible, a capacitor is installed at the output of the circuit.
Driver for LED lampsElectronic devices are expensive, but stabilize the current up to a maximum of 750 mA. The latest drivers of this type are usually installed on lamps with an E27 base. The main disadvantages are ripples and interference in the high-frequency range. If household appliances, such as a radio, are plugged into the same socket with a lamp, interference occurs at FM frequencies. . A good electronic driver should have two capacitors at once:

  • electrolytic, which smooths out pulsations;
  • ceramic, which lowers high frequencies.

This combination is rare, especially in Chinese-made drivers. IC savvy users can get the driver’s output parameters by changing the resistor values. Due to the high efficiency – about 95% – electronic drivers are used for a variety of purposes (to ensure the operation of automotive LED lamps, street and household lighting).

Based on capacitors

Drivers based on the use of capacitors are somewhat less popular. Almost all budget LED lamp circuits with such devices have similar characteristics.
Based on capacitorsDue to changes made by manufacturers to electrical circuits, some elements may be removed from them. Especially often they do not have a capacitor responsible for smoothing ripples. Advantages of capacitor drivers:

  • simplicity of design;
  • The efficiency tends to 100%, since power losses are observed only in resistors and junctions of semiconductor elements.

According to GOST, the allowable ripple rate is 10-20% and depends on the purpose of the room in which the lighting device operates.

Dimmable

A dimmer is a device that controls the brightness of LEDs. Many modern drivers incorporate these useful features.
DimmableAdvantages of dimmable drivers:

  • the user selects the level of illumination that is comfortable for the current moment;
  • the inclusion of a dimmer in current stabilizers allows you to economically consume both electricity and the life of the LEDs.

Execution options:

  • The dimming device is located between the power supply and the LED lamp. Such a device controls the electricity supplied to the LEDs. Usually these are pulse-width stabilizers (PWM) that correct the amount of current.
  • The device controls the power supply. It performs current correction. The brightness and color of the diodes changes.

Lifetime

The duration of the correct operation of the driver depends on its quality and operating conditions. But even the highest quality device has a much smaller resource than the LEDs connected to it. LED elements from well-known brands last about 100,000 hours. Estimated time of driver operation:

  • low quality – up to 20,000 hours;
  • average – up to 50,000 hours;
  • high – up to 70,000 hours.

For production and the street, it is recommended to take drivers with a long service life.

The duration of the current stabilizer for LEDs is influenced by external factors. The driver may fail for the following reasons:

  • high humidity in the room, which does not correspond to the degree of protection of the device;
  • sharp temperature changes;
  • poor ventilation;
  • incorrect load power calculation.

Most often, the driver breaks down due to the capacitor – it fails during power surges in the network.

How to choose a driver?

Most of the LED lighting drivers sold in the domestic market are made in China, are cheap, and are not of high quality. In Chinese LED lamp drivers, defective microcircuits are often found, it is not recommended to buy them. Such a device quickly fails, and it is unlikely that it will be possible to exchange it for a new one or return the money. Tips for choosing LED driver:

  • Take the current stabilizer along with the load.
  • Consider the load power that will be connected to the driver.
  • Pay attention to the body. It should indicate the power, voltage ranges (input and output), the nominal value of the stabilized current, the moisture and dust resistance class.

Maximum driver power

The output voltage depends on the number of diodes in the circuit and on the scheme of their inclusion. It must be greater than or equal to the sum of the energy spent by each block of the electrical circuit. The rated current is determined by the power of the elements and their brightness. The purpose of the stabilizer is to provide the diodes with the necessary energy. The total power of the LEDs is determined by the parameters of each element, their number and color. The amount of energy consumed is calculated according to the formula: P = PLED x N, where N is the number of diodes in the circuit, PLED is the power of one diode. The nominal value is taken 20-30% more than the calculated power: Pmax ≥ (1.2..1.3) * P. The color of the glow of the elements is also taken into account. It affects the output voltage. It is indicated directly on the device or on the packaging. For example, there are three 3W LEDs. Then the total power is 9 watts. Recommended driver Pmax = 9 x 1.3 = 11.7 watts.

Price

Drivers for LED lighting are sold in electrical stores, on the Internet, at retail outlets that deal in radio components. Buying online is the cheapest.
Driver for LED lampsApproximate prices for current stabilizers:

  • DC12V (power 18 W, input voltage 12 V, output 100-240 V) – 190 rubles;
  • LB0138 (6 W, 45 V, 220 V) – 170 rubles;
  • YW-83590 (21 W, 25-35 V, 200-240 V) – 690 rubles;
  • LB009 (150 W, 12 V, 170-260 V) – 750 rubles.

The PT4115 microcircuit – a buck converter – costs 150 rubles per piece. More powerful elements cost from 150 to several thousand rubles.

Other characteristics

When buying a driver, pay attention to the following characteristics:

  • Output voltage. Its value depends on the number of LEDs in the lamp, on the method of power supply and the voltage drop across the semiconductors. There are devices on the market with voltages from 2 to 50 V and more.
  • Rated current. It should be sufficient to provide optimal brightness.
  • LED color. It affects the voltage drop.

The dependence of electrical parameters on the color of the LEDs:

ColorVoltage drop, VCurrent strength, APower consumption, W
Red1.6-2.04

350

 

0.75
Orange2.04-2.10.9
Yellow2.1-2.181.1
Green3.3-41.25
Blue2.5-3.71.2

If the light source has three 1 W white light LEDs connected in series, you will need a driver with a voltage of 9-12 V and a current of 350 mA. The voltage drop across white crystals is 3.3 V. When connected in series, the voltages are summed up. It turns out 9.9 V, which satisfies the operating range of the driver. Depending on the modification, devices are used for a certain number of LEDs – one, two or more.

In everyday life and for phytolamps, it is recommended to use drivers in cases. They are more aesthetic and safer than frameless ones.

For example, LED drivers with 9918c chip in an LED lamp are suitable for driving non-dimmable lamps and support power up to 25W.

Driver connection

The driver is quite simple to connect to the LEDs. On its body there is all the necessary markings. An input voltage is applied to the input terminals (INPUT), and a string of LEDs is connected to the output terminals (OUTPUT). The main thing is to observe the polarity.

Input polarity

If the driver is powered by constant voltage, the positive pole of the power source is connected to its “+” terminal. For AC voltage, pay attention to the labeling of the input terminals. Marking options:

  • “L” and “N”. Apply phase to output “L”. You can find it with a special electrical screwdriver. Connect the neutral wire to the “N” terminal.
  • “~”, “AC” or no marking. In this case, the polarity is not important, you can not observe it.

Output polarity

Polarity must always be observed here. The “plus” wire is connected to the anode of the first semiconductor element, the “minus” wire is connected to the cathode of the last diode. Driver connection:
Connection220/12V LED lamp driver circuit (input/output voltage):
Scheme

Repair of LED lamp drivers

If the current regulator loses its ability to perform its functions, this can lead to damage to the LEDs. It is important to identify the breakdown in time. To test the LED lamp driver, 220 V is applied to its input. A constant voltage should appear at the output of a working driver. Moreover, its value will be slightly larger than the upper range indicated on the packaging of the device. This method is simple to implement, but does not make it possible to judge the health of the device. To check if the driver is correct, do the following:

  1. Install a resistor at the output of the current stabilizer. Its resistance is selected taking into account the given current. Determined by Ohm’s law: R=U/I.
  2. Take a resistor with the calculated resistance and the corresponding power.
  3. After installing the resistor, measure the output voltage with a tester. If it does not go beyond the operating range, the device is working properly.

The second way to search for driver failures:

  1. If the device has a fuse, ring it. The tester should show that the resistance is zero. If the resistance tends to infinity, replace the fuse. If the lamp lights up after turning on the network, the repair is over.
  2. If the fuse is not blown, look for a breakdown further. Check diode bridge.
  3. If the rectifier is in order, you will have to unsolder the smoothing capacitor and ring it. A small resistance, growing before our eyes, indicates the serviceability of the capacitor.
  4. For a simple driver, these checks will be enough to find the source of the problem. In complex current stabilizers, you will have to ring all the diodes and electrolytic capacitors.

When trying to find a breakdown, consider the principle of operation of the circuit:

  • Linear. In such drivers, protection against voltage drops is carried out using 5-100 Ohm resistors. One resistance is placed at the input of the rectifier (diode bridge). To reduce flicker, a large electrolytic capacitor is connected in parallel with the load.
  • Pulse. In these converters there are microcircuits that have protection against all threats – overheating, overloads and overvoltages. They should not break, but everything happens with Chinese drivers.

The problem of repairing drivers lies in the difficulty of selecting the right microcircuits. Especially if the stabilizer is made in China. If no method allows you to find the causes of the breakdown of the current stabilizer, you will have to contact a specialist. Or buy another driver.

Differences from power supplies

Driver many users mistakenly call the power supply. In fact, they are different devices. The power supply stabilizes the voltage, the driver – the current. If the LEDs are connected to the wrong power source, they quickly fail. The power supply can be:

  • Transformer. They are rare today, as in many respects they lose to their competitors. The transformer block makes 12 or 24 V from a voltage of 220 V. Then the alternating voltage is rectified to direct. It is applied to the load.
  • Pulse. In them, the voltage is straightened immediately – 220 V AC is converted to 220 V DC. Then it goes to the pulse generator, which creates an alternating voltage of high frequency. The last element is the transformer.

Both power supplies output a constant voltage of the same magnitude. Such devices are not suitable for LEDs, since they are “powered” by electric current. And the voltage drop across semiconductors is only one of their characteristics. If parameters are written on the LED, for example, 10 mA and 2.7 V, this means that more than the indicated Amperes cannot be passed through it – it will burn out. With the passage of a current of 10 mA, 2.7 V is lost on the semiconductor. This is precisely the loss, and not the voltage required to light the LEDs.

How to make a linear LED driver with your own hands?

Having ready-made microcircuits, any novice radio amateur can assemble a driver for LEDs. For this job, you need to be able to do two things – read electrical circuit diagrams and own a soldering iron. For example, you can assemble a current stabilizer for 3 W LEDs using the PowTech chip – PT4115 (China). The converter, created on the basis of this microcircuit, has a minimum of elements and high efficiency. The simplest current converter is assembled even from a phone charger. The following is an instruction for assembling a driver for three 1W LEDs. For work you will need:

  • Old mobile phone charger. For example, from Samsung – they are more reliable. Device parameters – 5 V and 700 mA.
  • Trimmer resistor with a resistance of 10 kOhm.
  • Three LED elements with a power of 1 W.
  • Cord with plug.

How to assemble the driver:

  1. Disassemble the charger, being careful not to damage its elements.Driver
  2. Use a soldering iron to solder a 5 kΩ resistor at the input. Replace it with an adjustable resistor.Soldering work
  3. Determine the output for the load and polarity in order to solder the LEDs correctly. They are pre-assembled in a serial circuit.Load output
  4. Unsolder the contacts from the cord and put a wire with a plug there. Before checking if the stabilizer works, make sure everything is connected correctly. If you make a mistake, there may be a short circuit.unsolder
  5. Adjust the current with the trimmer so that the LEDs light up.adjust
  6. If the light emitting elements are on, check the voltage, current, power with a tester.LEDs are on

If the LEDs are lit, there is no spark or smoke, the assembly went well – your DIY is ready. The use of a properly selected driver is an important condition for the high-quality and long-term operation of LED power supplies. The most reliable option is to buy a branded device along with LED lamps. If you understand circuits and are “friends” with a soldering iron, you can always assemble a suitable driver for LED elements.

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  1. Олег

    В значительной степени срок службы фотодиодной лампы зависит именно от качества драйвера, а еще точнее от производителя. Это вывод из личного опыта. Также от качества драйвера завит и потребляемая мощность светодиодной лампы, некоторые из драйвером сильно нагреваются, то есть часть потребляемой энергии идет на нагрев. Был очень приятно удивлен, что здесь представлена возможность создания драйвера своими руками, из блока питания. Обязательно попробую такой сделать, поскольку есть светодиодные лампы из сгоревшими драйверами.

    Reply
  2. Айна

    Из множество составляющих светодиодной лампы-драйвер наверно является одним из важнейших. Следовательно, при выборе самой лампы параметры типа драйвера зачастую не указываются. Это ссылается на то, что многие драйверы не долгослужащие. А тут подробно указано о том, как сделать качественный драйвер своими руками, что даже новички запросто разберутся в этом. В целом, статья стала для меня информативной и надеюсь, что в ближайшем будущем обязательно воспользуюсь знаниями полученными в ней

    Reply
  3. Виталий

    Много полезного и интересного для себя почерпнул из этой статьи. Конечно, лучше покупать уже готовый, проверенный драйвер, ведь от него напрямую зависит качество работы светодиодных ламп. Но приятно ведь и что-то сделать своими руками. Не знал, что старые телефонные зарядки, а их в доме полно (у всех членов семьи есть телефоны, зарядки часто выходят из строя), можно так эффективно, то есть с пользой для дела, использовать. Я и сам попробовал изготовить самодельный драйвер ради интереса, действуя пошаговым указаниям, у меня все получилось, чему очень рад.

    Reply
  4. Антон

    Решил в своем доме сам сделать всю электрику и сам все лампы установить решил. Потому что думал, что так будет дешевле  и вроде как, интереснее! Но я даже не думал, что с этим столько много проблем будет. А сложностей еще больше. К тому же я совсем новичок в этом деле и мне в двойне было сложно. Но многое у вас на сайте смог найти. У вас материал полезный подобран и нужный. Особенно, для таких “зеленых” как я, кто с электричеством и лампами никогда и не сталкивался. Спасибо большое за то, что понятно все расписали!

    Reply
  5. Саша

    Спасибо разработчикам, потому что
    я только на этом сайте смог найти, как собрать драйвер, понятно и с картинками. Было огромным удивлением, что есть расчётное функционированное время драйвера (из этого возникает вопрос, какой лучше брать?) эх, наткнулся бы я ещё на советы выбора драйвера чуть раньше, то не брал бы тот китайский, который и недели не прослужил.

    Reply
  6. Саша

    Спасибо разработчикам, потому что я только на этом сайте смог найти, как собрать драйвер, понятно и с картинками. Было огромным удивлением, что есть расчётное функционированное время драйвера (из этого возникает вопрос, какой лучше брать?) эх, наткнулся бы я ещё на советы выбора драйвера чуть раньше, то не брал бы тот китайский, который и недели не прослужил.

    Reply
  7. Елена

    Я немного увлекаюсь дизайном интерьера в плане хобби. Создаю очень много интересных вещей из подручных материалов. Вот недавно довелось делать светодиодные светильники. Я в этом деле дуб дубом, как, что и куда подсоединять, мне помогал супруг. Но думаю, все равно нужно научиться самой, авось пригодится. Из статьи узнала очень много полезного и нового для себя. Даже муж прочитал с любопытством, возможно, тоже открыл что-то для себя неизвестное. А вот своими руками сделать драйвер, очень здоровская идея.

    Reply
  8. Саня

    Довольно сложно в этом во всем разобраться. Я по молодости лет учился на электрика, но со временем все позабылось и сейчас, когда возникла необходимость, то пришлось вспоминать, а я и половины не помню, да и все немного изменилось. Мои знания, так скажем, устарели. По этой причине и стал искать информацию в интернете. Благо, что ваш сайт сразу нашел. Нигде таких подробных схем я еще не видел и не встречал, сразу знания немного освежились и стало хоть что-то понятно. Спасибо вам за информацию, которой вы делитесь!

    Reply
  9. Костя

    Согласен, срок службы светодиодной лампы напрямую зависит и от производителя, и от того, качественный драйвер стоит или нет. У меня был случай, когда лампа вышла из строя уже через месяц использования. Похоже, что сделана лампа была(догадайтесь с трех раз!)) в Китайской народной республике. Знающий человек говорит, что каждая третья светодиодная лампа, сделанная в Китае, сгорает всего за несколько дней использования. Насчет того, что от качества драйвера зависит и потребляемая мощность лампы, не уверен. Но не удивлюсь, что это так!

    Reply