Mc34063 negative voltage. Memory for the phone from the cigarette lighter on the MC34063. Features of the microcircuit - PWM or PWM
But in the basic configuration, he really lacked current to fully charge the smartphone, only about 500 mA. The device puffed with all its might, but the microcircuit overheated, and this had a negative effect on efficiency and performance in general.
I remind you not to bother - you can buy a cool ready-made PowerBank to your taste :)
Here, one comrade needed to make a Power Bank for a term paper, so a circuit with an external key element on a field-effect transistor was taken as the basis.
Just like that, connecting a field effect transistor to the output of an open emitter will not work, a driver made of a diode and a pnp transistor is used. The diagram is presented below, all the necessary calculation formulas are shown in the picture, in addition I can offer a calculator by which you can calculate the feedback resistors to obtain the required voltage (5 V is required to charge a smartphone). For a 5 Volt output voltage, resistors of 1k and 3k are suitable, 1k is the one to the ground. How to use the calculator is written at the first link in the article.
It was not difficult to separate the board, photo below, file at the end of the article.
We used smd elements interspersed with output elements.
The final implementation of the device allows you to charge any smartphone with the appropriate adapter. The current may well reach up to 2A, while not a single part is heated. Specifically, in this implementation, the output was a USB connector.
In essence, you see a STEP-UP converter on the MCP34063A + MOSFET transistor to amplify the current.
If you need to power from a small voltage, like from a lithium-ion battery, pulse the gate through a Schottky diode.
To power portable electronic equipment at home, mains power sources are often used. But this is not always convenient, since there is not always a free electrical outlet at the place of use. And if you need to have several different power sources?
One of the right decisions is to make a universal power supply. And as an external power source, use, in particular, the USB port of a personal computer. It's no secret that the standard one provides power for external electronic devices with a voltage of 5V and a load current of not more than 500 mA.
But, unfortunately, for the normal operation of most portable electronic equipment, 9 or 12V is required. A specialized microcircuit will help to solve the problem voltage converter on MC34063, which will greatly facilitate the manufacture with the required parameters.
Structural diagram of the mc34063 converter:
MC34063 Operating Limits
Description of the converter circuit
Below is a schematic diagram of a power supply option that allows you to get 9V or 12V from a 5V USB port on your computer.
The circuit is based on a specialized microcircuit MC34063 (its Russian counterpart K1156EU5). The MC34063 voltage converter is an electronic control circuit for a DC/DC converter.
It has a temperature compensated voltage reference (RTF), a variable duty cycle oscillator, a comparator, a current limiting circuit, an output stage, and a high current switch. This chip is specially made for use in boost, buck and invert electronic converters with the smallest number of elements.
The output voltage obtained as a result of operation is set by two resistors R2 and R3. The choice is made on the basis that at the input of the comparator (pin 5) there should be a voltage equal to 1.25 V. You can calculate the resistance of the resistors for the circuit using a simple formula:
Uout= 1.25(1+R3/R2)
Knowing the required output voltage and the resistance of the resistor R3, it is quite easy to determine the resistance of the resistor R2.
Since the output voltage is determined, you can greatly improve the circuit by including a switch in the circuit that allows you to receive all kinds of values as needed. Below is a variant of the MC34063 converter for two output voltages (9 and 12 V) 
Key Specifications for MC34063
- Wide range of input voltage values: from 3 V to 40 V;
- High output pulse current: up to 1.5 A;
- Adjustable output voltage;
- Converter frequency up to 100 kHz;
- Internal voltage reference accuracy: 2%;
- Short circuit current limitation;
- Low consumption in sleep mode.
- Reference voltage source 1.25 V;
- Comparator comparing the reference voltage and the input signal from input 5;
- Pulse generator resetting RS flip-flop;
- Element And combining signals from the comparator and generator;
- RS-trigger eliminates high-frequency switching of output transistors;
- Driver transistor VT2, in the emitter follower circuit, to amplify the current;
- The output transistor VT1 provides current up to 1.5A.
MC34063 boost converter
For example, I used this chip to get 12 V power for the interface module from the laptop USB port (5 V), so the interface module worked when the laptop was working, it did not need its own uninterruptible power supply.It also makes sense to use an IC to power contactors that need higher voltage than other parts of the circuit.
Although the MC34063 has been around for a long time, the ability to operate from 3 V allows it to be used in voltage regulators powered by lithium batteries.
Consider an example of a boost converter from the documentation. This circuit is designed for an input voltage of 12 V, an output voltage of 28 V at a current of 175 mA.
- C1 - 100uF 25V;
- C2 - 1500 pF;
- C3 - 330uF 50V;
- DA1 - MC34063A;
- L1 - 180 μH;
- R1 - 0.22 Ohm;
- R2 - 180 Ohm;
- R3 - 2.2 kOhm;
- R4 - 47 kOhm;
- VD1 - 1N5819.
Step-down converter on MC34063
Lowering the voltage is much easier - there are a large number of compensation stabilizers that do not require inductors, requiring fewer external elements, but for a pulse converter there is work when the output voltage is several times less than the input, or the conversion efficiency is simply important.The technical documentation provides an example of a circuit with an input voltage of 25 V and an output of 5 V at a current of 500mA.
- C1 - 100uF 50V;
- C2 - 1500 pF;
- C3 - 470uF 10V;
- DA1 - MC34063A;
- L1 - 220 μH;
- R1 - 0.33 Ohm;
- R2 - 1.3 kOhm;
- R3 - 3.9 kOhm;
- VD1 - 1N5819.
MC34063 inverting converter circuit
The third scheme is used less frequently than the first two, but no less relevant. Accurate measurement of voltages or amplification of audio signals often requires a bipolar supply, and the MC34063 can help you achieve negative voltages.The documentation provides a circuit that allows you to convert a voltage of 4.5 .. 6.0 V into a negative voltage of -12 V with a current of 100 mA.
- C1 - 100uF 10V;
- C2 - 1500 pF;
- C3 - 1000uF 16V;
- DA1 - MC34063A;
- L1 - 88 μH;
- R1 - 0.24 Ohm;
- R2 - 8.2 kOhm;
- R3 - 953 Ohm;
- VD1 - 1N5819.
MC34063 analogs
If the MC34063 is intended for commercial applications and has an operating temperature range of 0 .. 70°C, then its full counterpart MC33063 can operate in the commercial range of -40 .. 85°C.Several manufacturers produce MC34063, other chip manufacturers produce complete analogues: AP34063, KS34063. Even the domestic industry produced a complete analogue K1156EU5, and although it is a big problem to buy this microcircuit now, but here you can find many schemes of calculation methods specifically for K1156EU5, which are applicable to the MC34063.
If you need to develop a new device and the MC34063 seems to be the best fit, then you should pay attention to more modern analogues, for example: NCP3063.
The parts in the circuit are rated for 5V with a current limit of 500mA, with a ripple of 43kHz and 3mV. The input voltage can be from 7 to 40 volts.
The resistor divider for R2 and R3 is responsible for the output voltage, if they are replaced with a tuning resistor somewhere around 10 kOhm, then it will be possible to set the required output voltage. Resistor R1 is responsible for limiting the current. Capacitor C1 and coil L1 are responsible for the ripple frequency, capacitor C3 is responsible for the ripple level. The diode can be replaced with 1N5818 or 1N5820. To calculate the parameters of the circuit, there is a special calculator - http://www.nomad.ee/micros/mc34063a/index.shtml , where you only need to set the required parameters, it can also calculate the circuits and parameters of converters of two types not considered.
2 printed circuit boards were made: on the left - with a voltage divider on a voltage divider, made on two resistors of size 0805, on the right - with a variable resistor 3329H-682 6.8 kOhm. MC34063 microcircuit in a DIP package, under it are two tantalum capacitors of size D. Capacitor C1 is size 0805, output diode, current limiting resistor R1 is half a watt, at low currents, less than 400 mA, you can put a lower power resistor. Inductance CW68 22uH, 960mA.
Ripple waveforms, Rlimit = 0.3 ohm
These waveforms show ripples: on the left - without load, on the right - with a cell phone load, a 0.3 ohm limiting resistor, below with the same load, but a 0.2 ohm limiting resistor.
Ripple waveform, R limit = 0.2 ohm
Taken characteristics (not all parameters measured), at an input voltage of 8.2 V.
This adapter was made to charge a cell phone and power digital circuits on the go.
The article showed a board with a variable resistor as a voltage divider, I will place the corresponding circuit to it, the difference from the first circuit is only in the divider.
33 Responses to "DC-DC Buck Converter on MC34063"
Very much!
It's a pity, I was looking for 3.3 Uout, and I need more help (1.5A-2A).
Can you improve?
The article provides a link to a calculator for the scheme. According to it, for 3.3V, you need to set R1 \u003d 11k R2 \u003d 18k.
If you need more currents, then you need to either add a transistor, or use a more powerful stabilizer, for example LM2576.
Thank you! Sent.
If you put an external transistor, will current protection remain? For example, set R1 to 0.05 Ω, the protection should work at 3 A, because mikruha itself will not withstand this current, then the EU must be strengthened with a field worker.
I think the limitation (this chip has a current limit, not protection) should remain. The datasheet has a bipolar circuit and calculations for increasing the current. For higher currents, I can advise LM2576, it is just up to 3A.
Hello! I also assembled this circuit for car charging a mobile phone. But when he is “hungry” (discharged) he eats a very considerable current (870mA). for this mikruha it's still normal, it just needs to get warm. I collected both on a breadboard and on the board, the result is the same - it works for 1 minute, then the current just drops and the mobile phone turns off the charge.
I don’t understand only one thing ... why the author of the article does not have the same denomination from the calculated ones, in practice, with the calculator that cited the link in the article. according to the author's parameters "... with a ripple of 43 kHz and 3 mV." and 5V at the output, and the calculator with these parameters gives out C1 - 470 peak, L1 - 66-68 μH,
C3 - 1000uF. The question is: WHERE IS THE TRUTH?
At the very beginning of the article it is written that the article has been sent for revision.
I made mistakes during the calculations, and because of them the circuit gets so hot, you need to choose the right capacitor C1 and inductance, but so far all hands have not reached this circuit.
The mobile phone turns off the charge when a certain voltage is exceeded, for most phones this voltage is more than 6V with something volts. It is better to charge the phone with a smaller current, the battery will live longer.
Thanks to Alex_EXE for the answer! I replaced all the components using a calculator, the circuit does not heat up at all, the output voltage is 5.7V, and when loaded (charging a mobile phone) it gives out 5V - this is the norm, and for a current of 450mA, I chose the details using a calculator, everything came together in fractions of a volt. I took the coil for 100 μH (the calculator gave out: at least 64 μH, which means it can be more :). I will write all the components later, as I test it, if anyone is interested.
There are not so many sites like your Alex_EXE (Russian-speaking) on the Internet, develop it further if you can. Thank you!
Glad it helped 🙂
Write it down, someone might find it useful.
Ok, I write:
The tests were successful, the mobile phone is charging (the battery in my nokia is 1350mA)
-output voltage 5.69V (apparently 1mV lost somewhere :) - without load, and 4.98V with a "mobile" load.
- input onboard 12V (well, this is a car, it is clear that 12 is ideal, and so 11.4-14.4V).
Ratings for the scheme:
- R1 \u003d 0.33 Ohm / 1W (because it gets a little warm)
— R2=20K /0.125W
— R3=5.6K/0.125W
— C1=470p ceramics
- C2=1000uF/25v (low impedance)
— C3=100uF/50v
- L1 (as I already wrote above 100 μH, it is better if it is 68 μH)
That's all:)
And I have a question for you Alex_EXE:
I can’t find information on the Internet about “Ripple voltage on the load” and “Conversion frequency”
How to correctly set these parameters in the calculator, that is, to choose?
And what do they mean anyway?
Now I want to do battery charging on this mikruha, but you need to clearly understand these two parameters.
The less fluctuations, the better. I have 100uF and the ripple level is 2.5-5%, depending on the load, you have 1000uF - this is more than enough. Pulsation frequency is within normal limits.
I somehow understood about the ripples, this is how much the “voltage jumps”, well .... about:)
And here is the conversion frequency. What to do with her? seeks to reduce or increase? Google is silent about this as a partisan, or that's what I was looking for :)
Here I can’t tell you for sure, although the frequency from 5 to 100 kHz will be normal for most tasks. In any case, it depends on the task, analog and precision devices are most demanding on frequency, where fluctuations can be superimposed on the working signals, thereby causing their distortion.
Alexander writes 04/23/2013 at 10:50
Found what you need! Very handy. Thank you very much Alex_EXE.
Alex, please explain to the kettle, if a variable resistor is introduced into the circuit, within what limits will the voltage change?
is it possible using this circuit to make a 6.6 volt current source with adjustable voltage, Umax so that it does not exceed these same 6.6 volts. I want to make several groups of LEDs (slave U 3.3 volts and current 180 mA), in each group there are 2 LEDs, the last. connected. 12 volt power supply, but if necessary I can purchase another one. Thank you if you answer...))
Unfortunately, I did not like this design - it was painfully capricious. If in the future the need arises, I can return, but so far I have scored on it.
For LEDs, it is better to use specialized microcircuits.
The higher the conversion frequency, the better. the dimensions (inductance) of the inductor are reduced, but within reasonable limits - for the MC34063, 60-100 kHz is optimal. Resistor R1 will heat up, because. in fact, this is a current-measuring shunt, i.e. all the current consumed by both the circuit itself and the load flows through it (5V x 0.5A \u003d 2.5Watt)
The question is of course stupid, but is it possible to remove +5, ground and -5 volts from it? You don't need a lot of power, but you need stability, or do you have to install something extra like 7660?
Hello everyone. Guys who can help make the output 10 volts or better with adjustment. Ilya can you ask me to paint. Tell me please. Thank you.
From the mc34063 manufacturer's spec sheet:
maximum frequency F=100 kHz, typical F=33 kHz.
Vripple = 1 mV - typical value, Vripple = 5 mV - maximum.
—
10V output:
- for step-down DC, if the input is 12 V:
Vin=12V, Vout=10V, Iout=450mA, Vripple=1mV(pp), Fmin=34kHz.
Ct=1073 pF, Ipk=900 mA, Rsc=0.333 Ohm, Lmin=30 uH, Co=3309 uF,
R1=13k, R2=91k (10V).
- for step-up DC, if the input is 3 V:
Vin=3V, Vout=10V, Iout=450mA, Vripple=1mV(pp), Fmin=34kHz.
Ct=926 pF, Ipk=4230 mA, Rsc=0.071 Ohm, Lmin=11 uH, Co=93773 uF, R=180 Ohm, R1=13k R2=91k (10V)
Conclusion: for step-up DC with the given parameters, the microcircuit is not suitable, since Ipk = 4230 mA > 1500 mA is exceeded. Here is an option: http://www.youtube.com/watch?v=12X-BBJcY-w
Install a 10 V zener diode.
Judging by the waveforms, your inductor is saturated, you need a more powerful inductor. You can increase the conversion frequency, leaving the inductor of the same dimensions and inductance. By the way, the MC-shka quietly works up to 150 kHz, the main thing is internal. transistors should not be turned on with a “darlington”. As far as I understand, it can be connected in parallel to the power circuit?
And the main question: how to increase the power of the converter? I look, the conduits are small there - 47 microfarads at the input, 2.2 microfarads at the output ... Does the power depend on them? Solder there one by one, one and a half microfarads? 🙂
What to do, boss, what to do?!
It is very incorrect to use tantalum capacitors in power circuits! Tantalum does not like high currents and ripples very much!
> It is very incorrect to use tantalum capacitors in power circuits!
and where else to use them, if not in switching power supplies ?! 🙂
Excellent article. It was a pleasure to read. All in a clear, simple language without showing off. Even after reading the comments, I was pleasantly surprised, the responsiveness and ease of communication are on top. Why did I get on this topic. Because I'm collecting odometer winding for Kamaz. I found a circuit, and there the author strongly recommends that the microcontroller be powered in this way, and not through the roll. Otherwise, the controller lights up. I don’t know for sure, but probably the roll does not hold such an input voltage, and therefore the palitsa. Since there is 24 V on such a machine. But what I didn’t understand was that in the diagram according to the drawing, it seems to be a zener diode. The author of the odometer winding was assembled on smd components. And this ss24 zener diode turns out to be a smd Schottky diode. HERE on the diagram is also drawn as a zener diode. But it seems to be well understood, there is a diode and not a zener diode. Although maybe I'm confusing their drawing? maybe this is how Schottky diodes are drawn and not zener diodes? It remains to clarify such a small thing. But thanks a lot for the article.