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100W diode array driver circuit. Homemade driver for powerful LEDs. Necessary materials and tools

Lately powerful ultra-bright LEDs As light sources, they are increasingly gaining market share, displacing incandescent lamps and energy-saving fluorescent lamps. There are several reasons for this: low power consumption, long service life, small dimensions, safety, ease of installation.

Consumer electronics did not stand aside either - the use of LED backlighting in LCD TVs or monitors is much more profitable and reliable than before - with the help of fluorescent lamps.

But with all the advantages of LEDs, they also have their own characteristics - and due to non-linear current-voltage characteristic LED power supply should be carried out only with a stable current, with a value determined by the passport data of the device. A device that provides a stable supply current to a load is commonly referred to as driver.

Basic driver requirements: high efficiency, reliability, stability of the output current regardless of the supply voltage.
Most often, driver circuitry is based on the use of pulse circuits using a storage choke, a key element, and a key element control circuit operating at a frequency of 30-100 kHz. If working LED voltagebelow the voltage of the power source, in the driver circuit, the LED is connected in series with the inductor and the key element (the most common situation), and if you want to apply a voltage to the LED higher than that of the power source -a storage choke circuit is used, the current through which is interrupted at a high speed, which causes voltage spikes I ten times higher than the feeder.An increased voltage is applied to the LED, the current in the circuit of which is controlled and used to regulate the output voltage.

Drivers for powering low-voltage LEDs from voltage sources of 90 - 240 V are widely distributed and available, circuitry is sufficiently covered in various publications, specialized microcircuits are often used in drivers, providing a minimum number of external elements. In the case when several serially connected LEDs or a multi-chip LED matrix are connected to a source with a lower voltage, the circuit changes slightly.

The figure shows driver circuit for LED matrix with a voltage of about 32V and an operating current of 350 mA.

The main elements in the circuit are: storage choke L1 , key transistor VT1 and a master oscillator chip DA1 . The IC provides short edge pulses to drive the transistor VT1 , which allows you to get voltage surges up to 50V on the drain of the transistor (depending on the parameters of the inductor, transistor and the steepness of the control fronts). The current to the LED assembly is supplied through a current-sense resistor. R7 . When the current reaches 0.35A, the voltage on R7 is 0.7V, transistor VT2 opens and provides interruption of the start pulses. When the current decreases, the transistor start pulses VT1 appear again, providing stabilization of the current on the load. Resistors R3, R4 serve to limit the output voltage at the output when the load is turned off, preventing the failure of electronic components.

The diagram can use suitable chokes wound with wire 0.3 ... 1.0 mm on rod ferrite cores (somewhat worse on ferrite rings), having an inductance of 40 - 200 μH. Choke dimensions are determined by the required load power. As a transistor VT1 can be used n- channel field-effect transistors with a small gate-source capacitance, a drain current of 5-30A and a maximum drain voltage of over 55V. Capacitors C2, C4 must have low internal resistance to provide a large pulse current through the inductor L1 , it is desirable to use surface mount tantalum capacitors. The disadvantage of the circuit is the strong dependence of the circuit on the parameters of the inductor and field effect transistor.

The spotlights use LED matrices 10 - 100 W with an operating voltage ofm 32-34 V (matrix of 9 crystals ). The search for ready-made drivers in the distribution network did not lead to success - the found ones were suitable only for low-voltage LEDs.Due to the large required power and the condition of non-criticality to the type of elements used, the driver circuit has been somewhat modified. A common microcircuit is used as a master oscillator MC33063AP1 , which has a more sensitive current feedback input (1.2 V instead of 2.5 V for the previous circuit). To form trigger pulses with short fronts for a field-effect transistor, a driver chip is used. TLP250 , often used in various converters and uninterruptible power supplies to control powerful field or IGBT transistors. The use of this driver made it possible to use almost any powerful field-effect transistors, for example IRF8010 , which makes it easy to get an output power of 100 watts or more.



as a choke L1 used ready-made coils with a diameter of 15 mm, wound on rod ferrite cores from old monitors with a wire of 0.8 - 1.2 mm. The inductance of the coils should be 40 - 160 µH. The higher the inductance, the lower the operating frequency of the master oscillator can be. With an inductance of 40 µH, it should be about 100 kHz, and 160 µH - 30 kHz. The load current is determined by the resistance of the resistor R4 . It always drops 1.25 V. The resistance of this resistor is calculated by the formula: R (ohm) = 1.25 / I load (A). Resistors R2, R3 and zener diode VD2 are used to limit the output voltage to 50V when the load is turned off, otherwise the output voltage can reach 100V or more.

The circuit has a high efficiency, reaching 88%, so the heating of the elements is minimal. Transistor heatsink VT1 not required, enough cooling per PCB



The circuit can be used to power LED chains or LED arrays with an operating voltage of 15 - 50 V. For a different load and output voltage, it is necessary to recalculate the resistance R4, as well as the ratio of resistors R2, R3. It may be necessary to replace the VD1 diode with a more powerful one.

A properly assembled circuit starts working immediately. If there is no confidence in the serviceability of the elements or the correct installation, first, instead of the LEDs, a load resistor is connected in such a way that, in normal mode, the current through it and the voltage coincide with the operating parameters of the LED. In the case of using 10W LED matrices with an operating voltage of 32V and a current of 0.35 A, the resistor should be approximately 100 ohms and 10W. The board is connected to the power supply through a limiting resistor with a resistance of 3 .. 5 ohms. After making sure that everything is working properly and the current consumption does not exceed the calculated value, the resistor is turned off.

The advantages of LED paws have been discussed repeatedly. The abundance of positive feedback from users of LED lighting willy-nilly makes you think about Ilyich's own light bulbs. Everything would be nice, but when it comes to costing the conversion of an apartment to LED lighting, the numbers are a little “strain”.

To replace an ordinary 75W lamp, there is a 15W LED bulb, and a dozen of such lamps need to be changed. With an average cost of about $ 10 per lamp, the budget is decent, and the risk of acquiring a Chinese “clone” with a life cycle of 2-3 years cannot be ruled out. In light of this, many are considering the possibility of self-manufacturing these devices.

The theory of powering LED lamps from 220V

The most budget option can be assembled with your own hands from these LEDs. A dozen of these little ones cost less than a dollar, and are as bright as a 75W incandescent bulb. Putting everything together is not a problem, but you can’t connect them directly to the network - they will burn out. The heart of any LED lamp is the power driver. It depends on how long and well the light bulb will shine.

To assemble a 220 volt LED lamp with our own hands, let's look at the power driver circuit.

Network parameters significantly exceed the needs of the LED. In order for the LED to be able to work from the network, it is required to reduce the voltage amplitude, current strength and convert the AC voltage to DC.

For these purposes, a voltage divider with a resistor or capacitive load and stabilizers are used.

LED Light Components

A 220 volt LED lamp circuit will require a minimum number of available components.

  • LEDs 3.3V 1W - 12 pcs.;
  • ceramic capacitor 0.27uF 400-500V - 1 pc.;
  • resistor 500kΩ - 1MΩ 0.5 - 1W - 1 sh.t;
  • 100V diode - 4 pcs.;
  • electrolytic capacitors for 330uF and 100uF 16V, 1 pc.;
  • voltage regulator for 12V L7812 or similar - 1 pc.

Making a 220V LED driver with your own hands

The 220 volt ice driver circuit is nothing more than a switching power supply.

As a homemade LED driver from a 220V network, consider the simplest switching power supply without galvanic isolation. The main advantage of such schemes is simplicity and reliability. But be careful when assembling, since such a circuit does not have a limit on the output current. The LEDs will take their prescribed one and a half amps, but if you touch the bare wires with your hand, the current will reach ten amperes, and such a current shock is very noticeable.

The simplest driver circuit for 220V LEDs consists of three main stages:

  • Voltage divider on capacitance;
  • diode bridge;
  • voltage stabilization stage.

First cascade- capacitance on the capacitor C1 with a resistor. The resistor is necessary for the self-discharge of the capacitor and does not affect the operation of the circuit itself. Its value is not particularly critical and can be from 100kΩ to 1MΩ with a power of 0.5-1W. The capacitor is necessarily not electrolytic for 400-500V (effective peak voltage of the network).

When a half-wave of voltage passes through a capacitor, it passes current until the plates are charged. The smaller its capacity, the faster the full charge. With a capacity of 0.3-0.4 μF, the charging time is 1/10 of the half-wave period of the mains voltage. In simple terms, only a tenth of the incoming voltage will pass through the capacitor.

Second cascade- diode bridge. It converts AC voltage to DC. After cutting off most of the voltage half-wave by the capacitor, we get about 20-24V DC at the output of the diode bridge.

Third cascade– smoothing stabilizing filter.

A capacitor with a diode bridge acts as a voltage divider. When the voltage in the network changes, the amplitude at the output of the diode bridge will also change.


To smooth out the voltage ripple, we connect an electrolytic capacitor in parallel with the circuit. Its capacity depends on the power of our load.

In the driver circuit, the supply voltage for the LEDs must not exceed 12V. As a stabilizer, you can use the common element L7812.

The assembled circuit of the 220 volt LED lamp starts working immediately, but before connecting to the network, carefully insulate all bare wires and solder points of the circuit elements.

Driver option without current stabilizer

There are a huge number of driver circuits for LEDs from a 220V network on the network that do not have current stabilizers.

The problem of any transformerless driver is the ripple of the output voltage, and therefore the brightness of the LEDs. A capacitor installed after the diode bridge partially copes with this problem, but does not completely solve it.

There will be a ripple with an amplitude of 2-3V on the diodes. When we install a 12V regulator in the circuit, even taking into account the ripple, the amplitude of the incoming voltage will be above the cutoff range.

Voltage diagram in a circuit without a stabilizer

Diagram in a circuit with a stabilizer

Therefore, a driver for diode lamps, even assembled by oneself, will not be inferior in terms of pulsation to similar units of expensive factory-made lamps.

As you can see, assembling a driver with your own hands is not particularly difficult. By changing the parameters of the circuit elements, we can vary the values ​​of the output signal over a wide range.

If you have a desire to assemble a 220 volt LED spotlight circuit based on such a circuit, it is better to convert the output stage to 24V with an appropriate stabilizer, since the output current of the L7812 is 1.2A, this limits the load power to 10W. For more powerful lighting sources, you either need to increase the number of output stages, or use a more powerful stabilizer with an output current of up to 5A and install it on a radiator.

The use of LEDs as light sources usually requires a specialized driver. But it happens that the necessary driver is not at hand, but you need to organize the backlight, for example, in a car, or test the LED for the brightness of the glow. In this case, you can do it yourself for LEDs.

How to make an LED driver

The diagrams below use the most common items that can be purchased at any radio store. Assembly does not require special equipment - all the necessary tools are widely available. Despite this, with a careful approach, the devices work for a long time and are not much inferior to commercial samples.

Necessary materials and tools

In order to assemble a homemade driver, you will need:

  • Soldering iron with a power of 25-40 watts. You can use more power, but this increases the risk of overheating of the elements and their failure. It is best to use a soldering iron with a ceramic heater and a non-flammable tip, because. an ordinary copper sting oxidizes rather quickly, and it has to be cleaned.
  • Flux for soldering (rosin, glycerin, FKET, etc.). It is advisable to use a neutral flux, - unlike active fluxes (orthophosphoric and hydrochloric acids, zinc chloride, etc.), it does not oxidize contacts over time and is less toxic. Regardless of the flux used, after assembling the device, it is better to wash it with alcohol. For active fluxes, this procedure is mandatory, for neutral fluxes - to a lesser extent.
  • Solder. The most common is low-melting tin-lead solder POS-61. Lead-free solders are less harmful when inhaled during soldering, but have a higher melting point with less fluidity and a tendency to degrade the weld over time.
  • Small pliers for bending the leads.
  • Nippers or side cutters for biting the long ends of leads and wires.
  • Installation wires in isolation. Stranded copper wires with a cross section of 0.35 to 1 mm2 are best suited.
  • Multimeter for voltage control at nodal points.
  • Insulating tape or heat shrink tubing.
  • A small fiberglass breadboard. A 60x40 mm board will suffice.

Breadboard made of textolite for quick installation

Diagram of a simple driver for a 1W LED

One of the simplest circuits for powering a high-power LED is shown in the figure below:

As you can see, in addition to the LED, it includes only 4 elements: 2 transistors and 2 resistors.

In the role of the regulator of the current passing through the led, here is a powerful field-effect n-channel transistor VT2. Resistor R2 determines the maximum current passing through the LED, and also works as a current sensor for transistor VT1 in the feedback circuit.

The more current passes through VT2, the more voltage drops on R2, respectively, VT1 opens and lowers the voltage at the gate of VT2, thereby reducing the LED current. Thus, stabilization of the output current is achieved.

The circuit is powered from a constant voltage source of 9-12 V, current not less than 500 mA. The input voltage must be at least 1-2 V greater than the voltage drop across the LED.

Resistor R2 should dissipate 1-2 watts of power, depending on the required current and supply voltage. Transistor VT2 - n-channel, rated for a current of at least 500 mA: IRF530, IRFZ48, IRFZ44N. VT1 - any low power bipolar npn: 2N3904, 2N5088, 2N2222, BC547, etc. R1 - with a power of 0.125 - 0.25 W with a resistance of 100 kOhm.

Due to the small number of elements, assembly can be carried out by surface mounting:

Another simple driver circuit based on the LM317 linear controlled voltage regulator:

Here, the input voltage can be up to 35 V. The resistance of the resistor can be calculated using the formula:

where I is the current strength in amperes.

In this circuit, the LM317 will dissipate significant power with a large difference between the supply voltage and the LED drop. Therefore, it will have to be placed on a small one. The resistor must also be rated for at least 2 watts.

This scheme is more clearly discussed in the following video:

This shows how to connect a powerful LED using batteries with a voltage of about 8 V. With a voltage drop across the LED of about 6 V, the difference is small, and the microcircuit heats up slightly, so you can do without a heatsink.

Please note that with a large difference between the supply voltage and the drop on the LED, it is necessary to put the microcircuit on a heat sink.

Power driver circuit with PWM input

Below is a diagram for powering high-power LEDs:

The driver is based on a dual comparator LM393. The circuit itself is a buck-converter, that is, a pulsed step-down voltage converter.

Driver Features

  • Supply voltage: 5 - 24 V, constant;
  • Output current: up to 1A, adjustable;
  • Output power: up to 18W;
  • Output short circuit protection;
  • The ability to control brightness using an external PWM signal (it will be interesting to read how).

Operating principle

Resistor R1 with diode D1 form a reference voltage of about 0.7 V, which is additionally regulated by a variable resistor VR1. Resistors R10 and R11 serve as current sensors for the comparator. As soon as the voltage on them exceeds the reference, the comparator will close, thus closing a pair of transistors Q1 and Q2, and those, in turn, will close the transistor Q3. However, the inductor L1 at this moment tends to resume the passage of current, so the current will flow until the voltage across R10 and R11 becomes less than the reference, and the comparator again does not open transistor Q3.

The pair Q1 and Q2 acts as a buffer between the output of the comparator and the gate of Q3. This protects the circuit from false positives due to interference on the gate of Q3, and stabilizes its operation.

The second part of the comparator (IC1 2/2) is used for additional dimming with PWM. To do this, a control signal is applied to the PWM input: when TTL logic levels (+5 and 0 V) ​​are applied, the circuit will open and close Q3. The maximum signal frequency at the PWM input is about 2 kHz. This input can also be used to turn the device on and off using the remote control.

D3 is a Schottky diode rated up to 1A. If you can't find a Schottky diode, you can use a switching diode, such as FR107, but the output power will then be slightly reduced.

The maximum output current is adjusted by selecting R2 and including or excluding R11. This way you can get the following values:

  • 350mA (1W LED): R2=10K, R11 disabled,
  • 700mA (3W): ​​R2=10K, R11 connected, 1 ohm nominal,
  • 1A (5W): R2=2.7K, R11 connected, nominal 1 ohm.

Within narrower limits, the adjustment is made by a variable resistor and a PWM signal.

Building and configuring the driver

Driver components are mounted on a breadboard. First, the LM393 chip is installed, then the smallest components: capacitors, resistors, diodes. Then transistors are placed, and lastly a variable resistor.

It is better to place elements on the board in such a way as to minimize the distance between the connected pins and use as few wires as jumpers as possible.

When connecting, it is important to observe the polarity of the diodes and the pinout of the transistors, which can be found in the technical description for these components. Diodes can also be used in the resistance measurement mode: in the forward direction, the device will show a value of the order of 500-600 ohms.

To power the circuit, you can use an external DC voltage source of 5-24 V or batteries. Batteries 6F22 ("crown") and others have too little capacity, so their use is not advisable when using powerful LEDs.

After assembly, you need to adjust the output current. To do this, LEDs are soldered to the output, and the VR1 engine is set to the lowest position according to the diagram (checked with a multimeter in the “ringing” mode). Next, we apply a supply voltage to the input, and by rotating the VR1 knob we achieve the required brightness of the glow.

Item List:

Conclusion

The first two of the considered circuits are very simple to manufacture, but they do not provide protection against short circuits and have a rather low efficiency. For long-term use, the third circuit on the LM393 is recommended, as it does not have these disadvantages and has more power output adjustment capabilities.

For the design of LED lamps, power sources are constantly required - drivers. With a large volume, it is quite possible to arrange the assembly of drivers yourself, but the cost of such drivers is not so low, and the manufacture and soldering of double-sided printed circuit boards with SMD components is a rather laborious process at home.

I decided to get by with a ready-made driver. We needed an inexpensive driver without a case, preferably with the ability to adjust the current and dimming.

Scheme redrawn and slightly modified

Characteristics without capacitors ~ 0.9V and 8.7% (pulsation of the light flux)

The output capacitor is expected to halve the ripple ~ 0.4V and 4%

But a 10uF capacitor at the input reduces ripple by a factor of 9 ~ 0.1V and 1%, although the addition of this capacitor significantly reduces PF (power factor)

Both capacitors bring the output ripple characteristics closer to the nameplate ~ 0.05V and 0.6%

So the ripples are defeated with the help of two capacitors from the old power supply.

Refinement No. 2. Driver output current setting

The main purpose of the drivers is to maintain a stable current on the LEDs. This driver consistently outputs 600mA.

Sometimes you want to change the driver current. This is usually done by selecting a resistor or capacitor in the feedback circuit. How are these drivers doing? And why are three parallel low-resistance resistors R4, R5, R6 installed here?

Everything is correct. They can set the output current. Apparently, all drivers of the same power, but for different currents, differ precisely in these resistors and the output transformer, which gives different voltages.

If we carefully remove the 1.9Ω resistor, we get an output current of 430mA by removing both 300mA resistors.

You can also go the other way by soldering another resistor in parallel, but this driver produces a voltage of up to 35V and at a higher current we will get an excess in power, which can lead to driver failure. But 700mA is quite possible to squeeze out.

So, by choosing resistors R4, R5 and R6, you can reduce the output current of the driver (or increase it very slightly) without changing the number of LEDs in the chain.

Refinement 3. Dimming

There are three pins labeled DIMM on the driver board, which suggests that this driver can control the power of the LEDs. The datasheet for the microcircuit also speaks of the same, although there are no typical dimming schemes in them. From the datasheet, you can get information that by applying a voltage of -0.3 - 6V to leg 7 of the microcircuit, you can get smooth power control.

Connecting a variable resistor to the DIMM pins does nothing, in addition, leg 7 of the driver chip is not connected to anything at all. So again improvements.

We solder a 100K resistor to leg 7 of the microcircuit

Now applying a voltage of 0-5V between the ground and the resistor, we get a current of 60-600mA


To reduce the minimum dimming current, you must also reduce the resistor. Unfortunately, nothing is written about this in the datasheet, so you will have to select all the components experimentally. I was personally satisfied with dimming from 60 to 600mA.

If you need to organize dimming without external power, then you can take the driver supply voltage ~ 15V (leg 2 of the microcircuit or resistor R7) and apply it according to the following scheme.

And finally, I apply PWM from D3 arduino to the dimming input.

I am writing a simple sketch that changes the PWM level from 0 to maximum and back:

#include

void setup()(
pinMode(3, OUTPUT);
Serial.begin(9600);
analogWrite(3,0);
}

void loop() (
for(int i=0; i< 255; i+=10){
analogWrite(3,i);
delay(500);
}
for(int i=255; i>=0; i-=10)(
analogWrite(3,i);
delay(500);
}
}

I get dimming using PWM.

PWM dimming increases the output ripple by about 10-20% compared to DC control. Maximum ripple is approximately doubled when the driver current is set to half the maximum.

Checking the driver for a short circuit

The current driver must respond correctly to a short circuit. But it is better to check the Chinese. I don't like such things. Stick something under pressure. But art requires sacrifice. We short the output of the driver during operation:

The driver normally tolerates short circuits and restores its work. There is short circuit protection.

Summing up

Driver Advantages

  • Small dimensions
  • Low cost
  • Possibility to adjust the current
  • Dimmable

Minuses

  • High output ripple (eliminated by adding capacitors)
  • Dimming input needs to be soldered
  • Not enough normal documentation. Incomplete datasheet
  • During the work, another minus was discovered - interference on the radio in the FM range. It is treated by installing the driver in an aluminum case or a case pasted over with foil or aluminum tape

Drivers are quite suitable for those who are friends with a soldering iron or for those who are not friends, but are ready to endure output ripples of 3-4%.

useful links

From the cycle - cats are liquid. Timothy - 5-6 liters)))

Probably everyone, even a novice radio amateur, knows that in order to connect an ordinary LED to a power source, you need only one resistor. But what if the LED is powerful? Watt so 10. How to be then?
I will show you how to make a simple driver for a powerful LED with just two components.

For the stabilizer-driver we need:
1. Resistor -.
2. Chip - LM317 -.


LM317 is a stabilizer chip. Great for designing regulated power supplies or drivers to power LEDs, as in our case.

Advantages of LM317

  • The voltage stabilization range is from 1.7 (including the LED voltage - 3 V) to 37 V. An excellent characteristic for motorists: the brightness will not float at any speed;
  • Output current up to 1.5, you can connect several powerful LEDs;
    The stabilizer has a built-in protection system against overheating and short circuit.
  • The negative power of the LED in the switching circuit is taken from the power source, therefore, when attached to the car body, the number of mounting wires is reduced, and the body can play the role of a large heat sink for the LED.

High power LED driver circuit


I will connect a 3 watt LED. As a result, we will need to calculate the resistance for our LED. A 1 W LED consumes 350 mA, and a 3 W LED consumes 700 mA (you can see it in the datasheet). Chip LM317 - has a reference voltage of the stabilizer - 1.25 - this is a constant number. It must be divided by the current and get the resistance of the resistor. That is: 1.25 / 0.7 \u003d 1.78 ohms. We take the current in amperes. We choose the nearest resistor by resistance, since there are no resistors with a resistance of 1.78. We take 1.8 and assemble the circuit.

If the power of your LED exceeds 1 W, then the chip must be installed on a radiator. In general, the LM317 is rated for current up to 1.5.
You can power our circuit with a voltage of 3 to 37 volts. Agree, a solid range of nutrition is obtained. But the higher the voltage, the more the microcircuit heats up, keep this in mind.