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Description of the 150W step-up converter based on the UC3843A

grala1 9306 29
This content has been translated flag-pl » flag-en View the original version here.
  • Hello.
    Below I present to you a short description of the 150W inverter increasing the voltage - step-up configuration.

    Description of the 150W step-up converter based on the UC3843A

    Inverter data:
    - input voltage: 10-32VDC;
    - output voltage adjustable in the range: 12-35VDC;
    - efficiency: 6A (sometimes you can even find 10A in the sellers' descriptions);
    - power: 150W;
    - current at rest: 25mA;
    - efficiency stated by sellers: approx. 94%;
    - dimensions: 65x48x29mm.

    Description of the 150W step-up converter based on the UC3843A

    Description of the 150W step-up converter based on the UC3843A



    You need to spend about $ 2.5 for the purchase of such a converter when buying with a shipment, e.g. from Aliexpress, or about PLN 19 when buying with a shipment on Polish auction portals.
    The converter is sold with screwed mounting pins, which is very helpful when mounting it in the target system.
    The heart of our tested converter is the UC3843A converter controller. It is powered from the 78L09 voltage stabilizer, so the minimum input voltage of this converter is about 10VDC.
    The board also features a choke, a Schottky rectifier diode, a MOSFET transistor, two 1000uF capacitors, a 0.01? resistor used here to measure the current, a potentiometer to adjust the output voltage and a few other small elements.

    Diagram of the converter below.
    Description of the 150W step-up converter based on the UC3843A

    The converter is connected to the power source with cables, by screwing them to the 4-pin KF screw connector, and the output wires to the same connector.
    A multi-turn potentiometer is used to regulate the output voltage.
    I do not know about other versions of this converter, but in mine there is a 35V capacitor at the output, and the maximum voltage on the converter is also 35V, so it would be appropriate to replace this capacitor if someone intends to use the maximum output voltage.
    It's time to start testing.
    I powered the converter from a car battery so as not to have problems with power efficiency here.
    At the beginning, the measurement of the current consumption in the idle state - it came out about 23mA, so it is within the values declared by the manufacturer.
    I set the output voltage to 24VDC.
    Below is a table with measurements.
    Description of the 150W step-up converter based on the UC3843A

    Below is a graph of efficiency to output current.
    Description of the 150W step-up converter based on the UC3843A

    As you can see - here we managed to achieve an efficiency of about 90%, but above 4A (90W) at the output it drops quite drastically.
    The temperature of the converter here reached approx. 115 C, so you have to be careful not to burn yourself and it is best to provide the converter with a fan. I did not check what temperature the converter could reach. Each measurement here was approx. 40 seconds. I do not know if the converter would survive a longer 120W draw - I did not test it.
    After this test, I did one more, where I set the output voltage to the maximum to see how the output voltage behaves. In my case, this voltage was 33.5V.
    This voltage was maintained up to about 2.8A, and at about 5A the voltage was less than 21V.
    With this test, I did not measure the current consumption from the battery anymore.
    During the tests, the converter did not make any squeaks, hums or hums, you can say that you cannot hear its operation.
    The inverter was bought for a friend with the intention of using it as a power supply for a laptop in the car and to this day it works. I did not have the opportunity to measure the temperature or the power consumed there, but the converters with this application can be safely held in the hand without fear of burns. It has been in its possession for several months and has not caused any problems to date. It is used up to several hours a week.

    Note that this is a step-up converter, so it is not suitable for powering laptops in "TIRs", where there is 24VDC in the cigarette lighter socket.
    It should be remembered that this converter has no protections - i.e. there is no protection against reverse power connection, overload and too high temperature.
    If you want to take more power from it, you should equip it with a fan and you can also think about replacing the heat sinks, because these, as you can see, have something to do with higher powers.
    In the descriptions of the sellers you can find information that this inverter can give 100W maximum with natural cooling and a maximum of 150W with forced cooling.
    We can also find information that if the ambient temperature is higher than 40 C, the converter cooling should be increased.
    I have not examined this converter with an oscilloscope, so I will not comment on its "sowing" noise.

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    About Author
    grala1
    VAG group specialist
    Offline 
    grala1 wrote 9499 posts with rating 3981, helped 1363 times. Live in city Kalisz. Been with us since 2006 year.
  • #2
    MAREK MRK
    Level 18  
    Descriptions in the chart are reversed. I use such a converter and honestly say that with an input voltage of 12V and an output voltage of about 30V, and a power consumption around 35W, after a few hours the heat sinks are very warm. Currently, I have reduced the power consumed to about 7W and it does not heat up at all. The problem may be the choke, it heats up quite a lot under high loads, at least in my unit, maybe if it is replaced ... but it is not very disturbing. Is it disturbing? Probably yes, but not bothersome because I did not even feel it, and the receiver connected to it is about 40m away.
    Once upon a time I made a modification of one of these and I added a current regulation, unfortunately after the receiver was damaged, the inverter tried to obtain the set current and increased the voltage ... Unfortunately, in that application it was not possible to set the output voltage properly, only the current. Currently, I use it without modification, but during the adjustment I performed voltage measurements (so as not to exceed the max for the receiver) and current measurements (this was the most important for me).
    I can recommend this converter from myself.
    As for the charts, I hope no one will be offended when I say link for testing this converter with oscillograms.
  • #3
    grala1
    VAG group specialist
    MAREK MRK , thanks for vigilance - I have already corrected the descriptions on the chart axes.
    I am not offended :D
    I do not mind.
  • #4
    MAREK MRK
    Level 18  
    The converter asks to remove the heat sinks, solder the transistor and diode on the other side, screw the whole thing to the larger heat sink. In addition, change the choke or stick firmly present and it will be a pretty cool converter. After such a modification of the cooling, it can be successfully loaded without fear of heating up. I did tests and with a larger heat sink consuming 100W for about 2 hours, the heat sink was warm but the choke was hot. I think there is something wrong with it, but I don't have a "loose" one for testing and modification at the moment. Honestly, I would try to modify it.
  • #5
    padre_joseph
    Level 7  
    And could any of you tell me what function the S1 transistor performs in the system? I found no mention of it in the UC3843A datasheet.
  • #6
    Strumien swiadomosci swia
    Level 43  
    So I've used it many times to raise the 12v voltage to 15v and power the dipped headlights in many cars.
    First, the wires are soldered directly to the PCB.
    Secondly, the converter has voltage stabilization and holds 15V.
    Thirdly, he solders additional 2200yF / 35V capacitors to the input and output, otherwise these 2 explode.

    The fan does everything.
    Adds a washer between the screw and the TO220 bushing to ensure good pressure and not melt the washer.

    Incandescent lights have a stable power supply and shine significantly brighter.
    Power consumption for 2 bulbs 55W - 20A 12V, so after tjunungu they consume more power.
  • #7
    Pittt
    Level 32  
    Strumien swiadomosci swia wrote:

    Incandescent lights have a stable power supply and shine significantly brighter.


    And is there a drop in the life of the bulbs? Blackened?
  • #8
    Strumien swiadomosci swia
    Level 43  
    Nobody has ever bought a light bulb from me for 3 months. I also do not know, I have not checked light bulbs at home yet.
  • #9
    1 Marcin
    Level 17  
    Hello, I have been looking for some inverter for some time for my old laptop, which I use from time to time on my car.
    Small, cool and I have already ordered. We'll see how it works.
  • #10
    slavo666
    Level 18  
    Strumien swiadomosci swia wrote:
    Nobody has ever bought a light bulb from me for 3 months. I also do not know, I have not checked light bulbs at home yet.

    Seriously? Maybe he didn't buy light bulbs because you burned his whole car?

    Where did the idea of mounting something like this come from?
  • #11
    Strumien swiadomosci swia
    Level 43  
    Just back from Mafia Women, the bulbs are working fine.
  • #12
    joon
    Level 13  
    Raising the voltage of light bulbs in the car. No massacre. The spotlight is probably set off like a table at Durczok's, it's not shining so brightly.

    Description of the 150W step-up converter based on the UC3843A
  • #13
    Strumien swiadomosci swia
    Level 43  
    This graph is false because the bulbs are 12V and usually operate at 10-14V depending on the condition of the installation and the car.
    15V stabilized is not much more.
    Previously, I had it done on a 15V car amplifier, but it was a long time ago and I drove for a long time and it was from 10 years ago I had a Polonaise.
    So the charts suck.

    Added after 1 [minutes]:

    joon wrote:
    The spotlight is probably set off like a table at Durczok's, it's dimly lit so let's pick up the voltage

    No, it shone fine now it shines like xenon.
    Believe me, I correct stupid design engineers from these brands revered by Poles every day.
  • #14
    joon
    Level 13  
    Strumien swiadomosci swia wrote:
    This graph is false because the bulbs are 12V and usually operate at 10-14V depending on the condition of the installation and the car.
    15V stabilized is not much more.
    Then calculate as a percentage how much you increase the voltage on the bulb and how it will affect its durability. More precisely, how much will the current increase during switching on where the cold fiber has a much lower resistance.
  • #15
    Strumien swiadomosci swia
    Level 43  
    Ok tomorrow I will measure how much electricity it consumes.
  • #16
    Szyszkownik Kilkujadek
    Level 37  
    What is the resistance of the voltage adjustment potentiometer? 10k??
  • #18
    MAREK MRK
    Level 18  
    I know that this inverter is not insulated, but is there any similar isolated ground?
  • #19
    eurotips
    Level 38  
    Strumien swiadomosci swia wrote:
    This graph is false because the bulbs are 12V and usually operate at 10-14V depending on the condition of the installation and the car.
    15V stabilized is not much more.
    ...


    Well, hardly anyone realizes that in an efficient installation the bulb gets 14.8V and somehow swallows it.
    Here it will get stabilized 15V and even if you take your foot off the gas, it will not stop illuminating the road.
    The only problem is when switching on, because THIS module has no current limit, I do not know how switching on the cold filaments of the bulb looks in practice.

    The only problem is that such interference with the installation is illegal.
  • #20
    vodiczka
    Level 43  
    eurotips wrote:
    Here it will get stabilized 15V and even if you take your foot off the gas, it will not stop illuminating the road.
    First of all - what is the effect of taking your leg off the throttle if you don't get off the ground first?
    Secondly - with an efficient car installation, not overloaded with current receivers, you will maintain 13.9-14.0V even when the engine is idling.
    This inverter is only useful with the engine off :)
  • #21
    Szyszkownik Kilkujadek
    Level 37  
    Quote:
    The supply voltage has a significant effect on the luminous flux of the bulb and its durability. Even small voltage drops in the vehicle's electrical system, e.g. caused by bad electrical connections (battery terminals, bulb connectors, alternator connections) can cause a significant and noticeable difference in the amount of light on the road. On the other hand, the voltage higher than the rated voltage by only 5% causes a twofold decrease in the bulb life.
    [1]
    It's once. And two:
    Quote:
    The key parameters of a halogen lamp significantly change as a function of the supply voltage. Below the flux relationship (? ;) , power (P), color temperature (Tb) and durability (Tc) of halogen bulbs from the voltage (U) prevailing in the vehicle's electrical system, given as a percentage, related to the voltage 13.2 V .
    [2]
    And the graph:
    Description of the 150W step-up converter based on the UC3843A [3]
    source [1] [2] [3]: http://www.bosma-group.eu/pl/wsparcie-techniczne/#sz2
    I also suggest rethinking the 15V halogen power supply.
  • #22
    slavo666
    Level 18  
    Strumien swiadomosci swia wrote:

    Power consumption for 2 bulbs 55W - 20A 12V, so after tjunungu they consume more power.

    Believe me, I correct stupid design engineers from these brands revered by Poles every day.

    If stuffing a hot, disturbing Chinese converter with butt joints without any protection, risking burning the car, is for you "correcting the engineers" then you should be treated, because your modifications pose a threat to unaware customers. Nothing to discuss.
  • #23
    MegaMaster1996
    Level 11  
    And I will change the topic of discussion a bit :D Namely. Is this converter suitable for audio applications? ie raising the voltage for the amplifier?
  • #24
    Szyszkownik Kilkujadek
    Level 37  
    Better not, because there may be a lot of noise and it may not produce with strong bass, when there is an immediate surge in high power consumption.
  • #25
    Strumien swiadomosci swia
    Level 43  
    MegaMaster1996 wrote:
    Namely. Is this converter suitable for audio applications? ie raising the voltage for the amplifier?

    What amplifier?
  • #26
    MegaMaster1996
    Level 11  
    Some TDA 2x50Wniby. and i plan to raise the voltage to 21v from 12 / 14.4 in the car.
  • #27
    Szyszkownik Kilkujadek
    Level 37  
    Give it up.
  • #28
    Szyszkownik Kilkujadek
    Level 37  
    eurotips wrote:
    The only problem is when switching on, because THIS module has no current limit, I do not know how switching on the cold filaments of the bulb looks in practice.

    I just checked it out. The inverter has a problem with full startup. You can hear it squeaking and does not give full (set) tension. It limits the current to 5A.
    Test parameters:
    Ue: 12.2V
    Uout: 15.0V
    Load: 2 pcs. H7 55W (parallel of course)

    The converter behaves correctly when we set Uwyj to
  • #29
    Strumien swiadomosci swia
    Level 43  
    Szyszkownik Kilkujadek wrote:
    At 15V the bulb overheats, which is manifested by "smoking". :-D


    Because your bulb is dirty, the glass never smokes. I do not know at all where you have so much ignorance and incorrect technical thought.
    The bulb is smoking .... good.
  • #30
    Szyszkownik Kilkujadek
    Level 37  
    Strumien swiadomosci swia wrote:
    Szyszkownik Kilkujadek wrote:
    At 15V the bulb overheats, which is manifested by "smoking". :-D


    Because your bulb is dirty, the glass never smokes. I do not know at all where you have so much ignorance and incorrect technical thought.
    The bulb is smoking .... good.
    It is a waste of electricity to discuss with you.