Sometimes you need to get a high voltage from a low one. For example, for a high-voltage programmer powered by a 5-volt USB, add somewhere around 12 volts.
How to be? For this, there are DC-DC conversion circuits. As well as specialized microcircuits that allow you to solve this problem in a dozen parts.
Principle of operation
So how to make something more than five from, for example, five volts? You can think of many ways - for example, charge capacitors in parallel, and then switch them in series. And so many times a second. But there is an easier way, using the properties of inductance to maintain the current strength.
To make it very clear, I will first show an example for plumbers.
Phase 1
The flap closes abruptly. The flow has nowhere else to go, and the turbine, being accelerated, continues to press the liquid forward, because cannot stand up instantly. Moreover, she presses her with a force greater than the source can develop. Drives the slurry through the valve into the pressure accumulator. Where does the part (already with increased pressure) go to the consumer from? From where, thanks to the valve, it does not return.
Phase 3
And again the damper closes, and the turbine begins to violently push the liquid into the battery. Replenishing the losses that formed there in phase 3.
Back to diagrams
We get out of the basement, throw off the plumber's sweatshirt, throw the gas key into the corner and, with new knowledge, begin to fence the circuit.
Instead of a turbine, an inductance in the form of a choke is quite suitable. As a damper, a conventional key (in practice, a transistor), as a valve, naturally a diode, and a capacitor will take on the role of a pressure accumulator. Who else but he is able to accumulate potential. Mustache, the converter is ready!
Phase 1
The key opens, but the coil cannot be stopped. The energy stored in the magnetic field bursts outward, the current tends to be maintained at the same level as it was at the moment the key was opened. As a result, the voltage at the output from the coil jumps up sharply (to break the path of the current) and, breaking through the diode, is stuffed into a capacitor. Well, part of the energy goes into the load.
Phase 3
The key opens and the energy from the coil again breaks through the diode into the capacitor, increasing the voltage that sagged during phase 3. The cycle is closed.
As can be seen from the process, it can be seen that due to the greater current from the source, we are increasing the voltage at the consumer. So the equality of capacities must be observed here. Ideally, with a converter efficiency of 100%:
U source * I source = U cons * I cons
So if our consumer requires 12 volts and eats 1A at the same time, then from a 5 volt source into the converter it is necessary to feed as much as 2.4A. At the same time, I did not take into account the source losses, although they are usually not very large (the efficiency is usually about 80-90%).
If the source is weak and is not able to give 2.4 amperes, then at 12 volts wild ripples and a decrease in voltage will go - the consumer will devour the contents of the capacitor faster than the source will throw it there.
Circuitry
There are a lot of ready-made DC-DC solutions. Both in the form of microblocks and specialized microcircuits. I will not be smart and to demonstrate the experience I will give an example of a circuit on the MC34063A, which I have already used in the example.
- SWC / SWE pins of the transistor switch of the SWC microcircuit are its collector, and SWE is the emitter. The maximum current that it can draw is 1.5A of the input current, but you can also connect an external transistor to any desired current (more details in the datasheet on the microcircuit).
- DRC - composite transistor collector
- Ipk - current protection input. There the voltage is removed from the shunt Rsc, if the current is exceeded and the voltage on the shunt (Upk = I * Rsc) becomes higher than 0.3 volts, then the converter will stall. Those. to limit the input current to 1A, you need to put a 0.3 ohm resistor. I didn't have a 0.3 ohm resistor, so I put a jumper there. Will work, but without protection. If anything, then the microcircuit will kill me.
- TC - input of the capacitor that sets the operating frequency.
- CII - comparator input. When the voltage at this input is below 1.25 volts, the switch generates pulses, the converter works. As soon as it becomes larger, it turns off. Here, through the divider on R1 and R2, the feedback voltage from the output is started. Moreover, the divider is selected in such a way that when the voltage we need appears at the output, then 1.25 volts will be at the input of the comparator. Then everything is simple - is the output voltage lower than necessary? We thresh. Did you get it right? We turn off.
- Vcc - Circuit Power
- GND - Ground
All formulas for calculating denominations are given in the datasheet. I will copy from it here the most important table for us:
Etched, soldered ...
So that's it. A simple scheme, but allows you to solve a number of problems.
Thanks to the development of modern electronics, specialized microcircuits for current and voltage stabilizers are produced in large quantities. They are divided in functionality into two main types, DC DC step-up voltage converter and step-down. Some combine both types in themselves, but this affects the efficiency not for the better.
Once upon a time, many radio amateurs dreamed of impulse stabilizers, but they were rare and in short supply. The assortment in Chinese stores is especially pleasing.
- 1. Application
- 2. Popular conversions
- 3. Boost voltage converters
- 4. Examples of promoters
- 5. Tusotek
- 6. On XL4016
- 7. On XL6009
- 8. MT3608
- 9. High-voltage 220
- 10. Powerful converters
Application
I recently purchased many different LEDs for 1W, 3W, 5W, 10W, 20W, 30W, 50W, 100W. All of them are of low quality, in order to compare them with high quality ones. To connect and power this whole bunch, I have 12 V and 19V power supplies from laptops. I had to actively flip through Aliexpress in search of low-voltage LED drivers.
Modern step-up DC / DC voltage converters and step-down converters were purchased, for 1-2 Amperes and powerful for 5-7 amperes. In addition, they are perfect for connecting a laptop to 12V in a car, they will pull 80-90 watts. They are quite suitable as a charger for 12V and 24V car batteries.
In Chinese online stores, voltage stabilizers are a little more expensive.
Popular microcircuits for step-up switching regulators are:
- LM2577, obsolete with low efficiency;
- XL4016, 2 times more effective than 2577;
- XL6009;
- MT3608.
Stabilizers are designated as AC-DC, DC-DC. AC is alternating current, DC is direct current. This will make it easier to find if specified in the request.
Making a DC DC boost converter with your own hands is not rational, I will spend too much time on assembly and adjustment. You can buy from the Chinese for 50-250 rubles, this price includes delivery. For this amount I will get an almost finished product that can be finalized as quickly as possible.
These pulse ICs are used in conjunction with others, wrote characteristics and datasheet for popular ICs for power supply,.
Popular conversions
Stabilizers-boosters are classified into low-voltage and high-voltage from 220 to 400 volts. Of course, there are ready-made blocks with a fixed boost value, but I prefer custom ones, they have wider functionality.
Most often, transformations are in demand:
- 12V - 19V;
- 12 - 24 Volts;
- 5 - 12V;
- 3 - 12V
- 12 - 220V;
- 24V - 220V.
Boosts are called car inverters.
Boost voltage converters
My laboratory power supply is powered by a 19V 90W laptop unit, but this is not enough to test the series connected LEDs. A series LED string requires 30V to 50V. Buying a ready-made unit for 50-60 Volts and 150W turned out to be expensive, about 2000 rubles. Therefore, I ordered the first boost stabilizer for 500 rubles. with an increase to 50V. After checking, it turned out that it was up to a maximum of 32V, because there are 35V capacitors at the input and output. I convincingly wrote my indignation to the seller, and after a couple of days they returned the money to me.
I ordered a second one to 55V under the Tusotek brand for 280 rubles, the booster turned out to be excellent. From 12V, it easily increases to 60V, the tuning resistor did not turn higher, it will suddenly burn out. The radiator is glued to a heat-conducting glue, so we couldn't see the marking of the microcircuit. The cooling is done a little wrong, the heatsink of the Schottky diode and controller is attached to the board and not to the heatsink.
Examples of promoters
XL4016
Consider the 4 models I have in stock. I didn't waste time on the photo, I took the sellers too.
Specifications.
| Tusotek | XL4016 | Driver | MT3608 | |
| Input, V | 6 - 35V | 6 - 32V | 5 - 32V | 2-24V |
| Input current | up to 10A | up to 10A | — | — |
| Output, V | 6 - 55V | 6 - 32V | 6 - 60V | up to 28V |
| Output current | 5A, max 7A | 5A, max 8A | max 2A | 1A, max 2A |
| Price | 260 RUB | 250rub | 270 RUB | 55rub |
I have a lot of experience with Chinese goods, most of them have shortcomings right away. Before using them, I inspect and modify them to increase the reliability of the entire structure. These are mainly assembly problems that arise when assembling products quickly. I am modifying LED floodlights, lamps for the home, car lamps for low and high beam, controllers for controlling daytime running lights of DRL. I recommend everyone to do this, for a minimum of time spent, the service life can be doubled.
Be careful, not all are protected against short circuit, overheating, overload and incorrect connection.
The real power depends on the mode, the specifications indicate the maximum. Of course, the characteristics of each manufacturer will differ, they put different diodes, the choke is wound with a wire of different thicknesses.
Tusotek
In my opinion, the best of all boost stabilizers. Some have elements that do not have a margin of performance or they are lower than those of PWM microcircuits, which is why they cannot give even half of the promised current. Tusotek has a 1000mF 35V capacitor at the input, 470mF 63V at the output. They are soldered to the board with the heat sink side with a metal plate. But they were soldered badly and obliquely, there is only one edge on the board, a slot under the other. Indiscriminately it is not clear how well they are sealed. If it's really bad, then it is better to dismantle them and put this side on the radiator, the cooling will improve 2 times.
The variable resistor sets the required number of volts. It will remain unchanged if you change the voltage at the input, it does not depend on it. For example, I put 50V at the output, raised it to 12V at the input from 5V, the supplied 50V did not change.
On XL4016
This converter has such a feature that it can only increase up to 50% of the input number of volts. If you connect 12V, then the maximum increase will be 18V. The description indicated that it can be used for laptops that are powered by a maximum of 19V. But its main purpose turned out to be working with laptops from a car battery. Probably the limitation of 50% can be removed by changing the resistors that set this mode. The output volts directly depend on the number of inputs. 
The heat dissipation is much better, the radiators are installed correctly. Only instead of thermal paste, there is a heat-conducting gasket to avoid electrical contact with the radiator. The input is a 470mF 50V capacitor, the other end is 470mF at 35V.
On XL6009
Representative of modern efficient converters, like the outdated models on the LM2596, are available in several versions, from miniature to models with voltage indicators.
Efficiency example:
- 92% when converting 12V to 19V, load 2A.
The datasheet immediately indicates the scheme of using a laptop as a power supply in a car from 10V to 30V. It is also easy to implement a bipolar supply at +24 and -24V on the XL6009. As with most converters, the efficiency decreases the higher the voltage difference and the greater the Ampere.
MT3608
Miniature model with good efficiency up to 97%, PWM frequency 1.2 MHz. Efficiency increases with increasing input voltage and decreases with increasing current. On the MT3608 boost converter, you can count on a small current, internally limited to 4A in case of a short circuit. In volts, it is advisable not to exceed 24.
High voltage 220
Conversion units from 12, 24 volts to 220 are widespread among motorists like. Used to connect devices powered by 220V. The Chinese mainly sell 7-10 models of such modules, the rest are ready-made devices. Price from 400 rubles. Separately, I want to note that if, for example, 500W is indicated on the finished unit, then this will often be a short-term maximum power. The real long-term will be about 240W.
Powerful converters
For special cases, powerful DC-DC boost converters for 10-20A and up to 120V are needed. I will show you several popular and affordable models. They mostly do not have a label or the seller hides it so that they do not buy elsewhere. I have not personally tested it, in terms of voltage, they coexist according to the promised characteristics. But the ampere will be slightly smaller. Although products of this price category always hold the declared load, I bought similar devices only with LCD screens.
600W
Powerful # 1:
- power 600W;
- 10-60V converts to 12-80V;
- price from 800 rubles.
You can find it by request "600W DC 10-60V to 12-80V Boost Converter Step Up"
400W
Powerful # 2:
- power 400W;
- 6-40V converts to 8-80V;
- at the output up to 10A;
- price from 1200 rubles.
To search, specify in the search engine "DC 400W 10A 8-80V Boost Converter Step-Up"
B900W
Powerful # 3:
- power 900W;
- 8-40V converts to 10-120V;
- at the output up to 15A.
- price from 1400 rubles.
The only unit that is designated as B900W and can be easily found.
Today we will consider several circuits of simple, one might even say - simple, pulse voltage converters DC-DC (converters of constant voltage of one magnitude, to a constant voltage of another magnitude)
Why pulse converters are good. Firstly, they have a high efficiency, and secondly, they can operate at an input voltage lower than the output voltage. Pulse converters are divided into groups:
- - down, up, inverting;
- - stabilized, unstabilized;
- - galvanically isolated, non-isolated;
- - with a narrow and wide range of input voltages.
For the manufacture of homemade pulse converters, it is best to use specialized integrated circuits - they are easier to assemble and not capricious when setting up. So, we present for review 14 schemes for every taste:
This converter operates at a frequency of 50 kHz, galvanic isolation is provided by a T1 transformer, which is wound on a K10x6x4.5 ring made of 2000NM ferrite and contains: primary winding - 2x10 turns, secondary winding - 2x70 turns of PEV-0.2 wire. Transistors can be replaced with KT501B. The current from the battery, in the absence of load, is practically not consumed.
Transformer T1 is wound on a ferrite ring with a diameter of 7 mm, and contains two windings of 25 turns of wire PEV = 0.3.
A push-pull unstabilized converter based on a multivibrator (VT1 and VT2) and a power amplifier (VT3 and VT4). The output voltage is selected by the number of turns of the secondary winding of the pulse transformer T1.
A stabilizing type converter based on the MAX631 microcircuit of the MAXIM company. Generation frequency 40 ... 50 kHz, storage element - choke L1.
You can use one of the two microcircuits separately, for example the second, to multiply the voltage from two batteries.
Typical circuit for switching on a pulse boost stabilizer on the MAX1674 microcircuit from MAXIM. Operability is maintained at an input voltage of 1.1 volts. Efficiency - 94%, load current - up to 200 mA.
It allows you to get two different stabilized voltages with an efficiency of 50 ... 60% and a load current of up to 150 mA in each channel. Capacitors C2 and C3 are energy storage devices.
8. Pulse step-up stabilizer on the MAX1724EZK33 microcircuit company MAXIM
Typical circuit for switching on a specialized microcircuit of the company MAXIM. It remains operational at an input voltage of 0.91 volts, has a small-sized SMD case and provides a load current of up to 150 mA with an efficiency of 90%.
Typical circuit for switching on a pulsed buck stabilizer on a widely available TEXAS microcircuit. Resistor R3 regulates the output voltage in the range of + 2.8 ... + 5 volts. Resistor R1 sets the short-circuit current, which is calculated by the formula: Isc (A) = 0.5 / R1 (Ohm)
Integral voltage inverter, efficiency - 98%.
Two isolated voltage converters DA1 and DA2, connected in a “non-isolated” circuit with a common “ground”.
The inductance of the primary winding of the T1 transformer is 22 μH, the ratio of the turns of the primary winding to each secondary is 1: 2.5.
Typical circuit of a stabilized boost converter based on a MAXIM microcircuit.
Here is an overview of a micropower voltage converter that will do little for anything.
Assembled quite well, compact size 34x15x10mm 
It is stated:
Input voltage: 0.9-5V
With one AA battery, output current up to 200mA
With two AA batteries, output current 500 ~ 600mA
Efficiency up to 96%
Real converter circuit 
The very small capacity of the input capacitor immediately catches the eye - only 0.15 μF. Usually they put it more than 100 times, apparently they naively count on the low internal resistance of the batteries :) Well, they put it like that, God bless him, if necessary, you can change it - immediately set it to 10mkF. Below in the photo is a native capacitor. 
The dimensions of the throttle are also very small, which makes one think about the veracity of the declared characteristics.
A red LED is connected at the input of the converter, which starts to glow when the input voltage is more than 1.8V
Checked for the following stabilized input voltages:
1.25V - voltage of Ni-Cd and Ni-MH battery
1.5V - voltage of one galvanic cell
3.0V - voltage of two galvanic cells
3.7V - Li-Ion battery voltage
At the same time, he loaded the converter until the voltage dropped to a reasonable 4.66V
Open circuit voltage 5.02V
- 0.70V - minimum voltage at which the converter starts to work at idle. At the same time, the LED naturally does not light up - there is not enough voltage.
- 1.25V no-load current 0.025mA, the maximum output current is only 60mA at a voltage of 4.66V. The input current is 330mA, the efficiency is about 68%. The LED naturally does not glow at this voltage. 
- 1.5V no-load current 0.018mA, maximum output current 90mA at 4.66V. The input current is 360mA, the efficiency is about 77%. The LED naturally does not glow at this voltage. 
- 3.0V no-load current 1.2mA (mainly consumes LED), maximum output current 220mA at 4.66V. The input current is 465mA, the efficiency is about 74%. The LED glows normally at this voltage. 
- 3.7V no-load current 1.9mA (consumes mainly LED), maximum output current 480mA at 4.66V. The input current is 840mA, the efficiency is about 72%. The LED glows normally at this voltage. The converter starts to warm up slightly. 
For clarity, I summarized the results in a table. 
Additionally, at an input voltage of 3.7V, I checked the dependence of the conversion efficiency on the load current
50mA - 85% efficiency
100mA - 83% efficiency
150mA - 82% efficiency
200mA - 80% efficiency
300mA - 75% efficiency
480mA - 72% efficiency
As it is easy to see, the lower the load, the higher the efficiency.
It falls short of the stated 96%
Output voltage ripple at 0.2A load 
Output voltage ripple at 0.48A load 
As it is easy to see, at the maximum current, the ripple amplitude is very large and exceeds 0.4V.
Most likely this is due to the output capacitor of a small capacity with a high ESR (measured 1.74 Ohm)
Working frequency of conversion about 80kHz
I soldered additional 20μF ceramics to the output of the converter and received a 5 times reduction in ripple at maximum current! 
Conclusion: the converter is very low-power - this must be taken into account when choosing it to power your devices
This is a device designed to obtain one or more voltages of another level from the voltage of one level. Sometimes this is absolutely necessary in our practice, for example, if we are designing a device with a low-voltage power supply from a Li-Ion battery and in the circuit of this device there are operational amplifiers that require power from a bipolar source ∓ 15B. Or another example. Suppose we need to power a microcontroller device with a nominal voltage of 5 volts from a lithium ion battery. In this and similar cases, the developer has to use DC voltage converters.
This article will focus on switching converters that have obvious advantages, the main one of which is high efficiency. Pulse voltage converters are a very wide class of devices. They can be stabilized or non-stabilized, with or without galvanic isolation of input from output. also converters can be divided into boost, buck and inverting (for example, a converter that, powered by a voltage of + 5V, gives a voltage of -5V at the output)
Electronic component manufacturers now produce a wide range of specialty ICs for use in DC-DC applications. Converters assembled on such chips have stable characteristics and high reliability. nevertheless, the pulse converter can be assembled using conventional discrete transistors. This article provides some very simple diagrams that you can use to solve simple design problems.
The very common MAX232 is used to convert the UART interface to RS232 signals. This microcircuit already has built-in voltage converters, which we can use for our own selfish purposes.
Diagram 1. Unusual use of the MAX232 chip
such a converter can provide voltage
∓ 9V at a small current of 5..8 mA. Such a converter can be used to power one or two operational amplifiers. the main advantage is simplicity. It is advisable to use this scheme if something needs to be done quickly, and there is nothing at hand except the MAX232 microcircuitScheme 2. Simple unstabilized converter on two transistors
One of the simplest schemes. the parameters of such a converter depend on the parameters of the transistors used, the conversion frequency and the characteristics of the transformer. The circuit shown in the figure operates at a frequency of about 50 kHz.
The T1 transformer is homemade. It can be wound on a ferrite ring made of 2000HM material with dimensions 10x6x4. the primary winding consists of 20 turns with a tap from the middle. Secondary - 140 turns also with a tap from the middle. Wire diameter - not less than 0.2 mm. Transistors can be replaced with BC546 or others. if no load is connected to the converter, it practically does not consume current from the power supply. This is one of its advantages (besides simplicity).
Scheme 3. Simple unstabilized transducer - multivibrator.
The next practical circuit is a four-transistor push-pull converter. the heart of the circuit is a conventional multivibrator with two transistors VT1 and VT2.
The transistors VT3 and VT4 serve as drivers for the windings of the pulse transformer. A half-wave rectifier on the VD3 diode is connected to the secondary winding of the pulse transformer. The ripple in the output voltage is smoothed out by capacitor C3. The output voltage of this converter can be changed over a wide range by changing the number of turns of the secondary winding of the transformer.
Scheme 4. Stabilized converter on two transistors.
An interesting circuit that allows you to power from a low-voltage source (for example, from one alkaline 1.5 V element), for example, a small device on a microcontroller that requires a 5 V supply. The circuit tries to maintain a constant voltage at the output of about 4.7 V. The feedback signal is removed from the resistor R2 and is applied to the base of the first transistor VT1. transformer T1 can be wound on a ferrite ring with a diameter of 7 mm. Both windings are the same, 20 turns of wire with a diameter of 0.3 mm. You can wind the windings in two wires. When connecting, take into account the beginning and end of the windings. If you make a mistake, the converter will not work. In this case, swap the wires of one of the windings. Coil L1 - any choke with an inductance in the region of 10 μH. The choke can be used industrial or wound by yourself. You can measure inductance using this inexpensive device. The choke, together with the capacitor C3, smoothes the ripple of the output voltage.
This fairly high-quality and convenient converter is built on the basis of a specialized microcircuit from the MAXIM company. Can be used to generate +12 volts in a device powered by a single 3 to 5 volt power source. Choke L1 can be wound on a small ferrite ring or on a small ferrite core. It is convenient to measure the inductance of the coils with these instruments. The circuit provides 120 mA output current. Microcircuit MAX734.
Scheme 5. A very simple converter on a specialized chip.
Another DC-DC converter using a microcircuit from MAXIM. The main advantage is the exceptional simplicity and unpretentiousness of this scheme. There are only 4 parts in the device, including the MAX631 microcircuit. The main and obvious purpose of such a converter is to power a 5V circuit from a source with a lower voltage of 3.2 volts. For example, from one Li-Ion battery.
Diagram 6. Stabilized DC-DC converter with bipolar output
∓
12 in
This very useful circuit can come in handy if your design only has one 4..5 volt power supply, but you need to use components that require a bipolar power supply. for example operational amplifiers (op amps). The heart of the converter is the LM2587-12 microcircuit. A pulse transformer can be implemented on a ferrite ring or on an armored core. The inductance of the primary winding should be about 22 μH (you can measure it with this device), and the ratio of the number of turns of the primary winding to the secondary winding = 1: 2.5. That is, for example, the inductance of 22 μH on the core that you have available is obtained with the number of turns 50. Then the number of turns of each of the secondary windings will be 2.5 * 50 = 125
Scheme 7. Stabilized DC-DC converter for two different voltages
If your design has digital microcircuits with a supply voltage of both 5 and 3.3 V, then this converter may come in handy. The circuit operates on a voltage in the region of 3 V and allows obtaining voltages of 3.3 and 5 V at the output. The load current for each output can reach 150 mA. As you can see from the diagram, the device uses 2 MCP1252 microcircuits from MICROCHIP
Scheme 8. DC-DC converter for two different voltages on microcircuits from YCL Elektronics
DC-DC converters for different voltages can be assembled on chips manufactured by YCL Elektronics. In this case, these are DC-102R microcircuits in the minus 5 V channel and DC-203R in the +12 V channel. At the -5 V output, the load current can reach 360 mA. On the +12 V output, the current is less - 150 mA.
Diagram 9.DC-DC boost converter on MAX1724EZK33
This DC-DC converter on a chip
