What is Buck converter: Definition and 35 Discussions

A buck converter (step-down converter) is a DC-to-DC power converter which steps down voltage (while drawing less average current) from its input (supply) to its output (load). It is a class of switched-mode power supply (SMPS) typically containing at least two semiconductors (a diode and a transistor, although modern buck converters frequently replace the diode with a second transistor used for synchronous rectification) and at least one energy storage element, a capacitor, inductor, or the two in combination. To reduce voltage ripple, filters made of capacitors (sometimes in combination with inductors) are normally added to such a converter's output (load-side filter) and input (supply-side filter).Switching converters (such as buck converters) provide much greater power efficiency as DC-to-DC converters than linear regulators, which are simpler circuits that lower voltages by dissipating power as heat, but do not step up output current.Buck converters can be highly efficient (often higher than 90%), making them useful for tasks such as converting a computer's main (bulk) supply voltage (often 12 V) down to lower voltages needed by USB, DRAM and the CPU (5V, 3.3V or 1.8V, see PSU).

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  1. manoj1996

    Trouble building a Buck Converter

    Hii i have design PCB Board and i have solder components i have given input Vin=32V and Vout= 12V but i am getting Vout= 29V. Please check any changes in my schematic.
  2. C

    Sources of voltage ripple in buck converter

    I am reading a book 'Fundamentals of Power Electronics' - Erickson. The book begins with a buck converter and the assumptions that we use so that we do not have to deal with 2nd order equations. I will first explain what the book says What the book says? The book says that the LC filter of a...
  3. PhysicsTest

    Designing a 24-100V to 12V Buck Converter Circuit

    I need to design a Buck converter circuit with the following requirements 24-100V (2 - 10 Amps) to 12V (20 Amps) Output. From the net i could get the below circuit. First major question is, do i need to interface a micro controller to achieve the functionality to drive the MOSFET? I am...
  4. sodoyle

    Synchronous Buck Converter Switching

    For a synchronous buck converter, does soft switching have to be implemented? I assume there will be some ringing if not. If soft switching is required/recommended, can it be implemented on just one of the switches to simplify control and still have most of the benefit?
  5. sodoyle

    Building a Buck Converter Using the LT1170

    Hi, I am trying to use an LT1170 to convert between 25-50 Vin to 5 Vout. Actually, I would like to keep a constant 5 V out regardless of the input. To do that I know the input would have to be 5 V plus any voltage drops with a 100% duty cycle but it's going to be low current so large duty cycles...
  6. J

    Electronics Designing a buck converter with feedback and a regulated output

    I had a bunch of questions regarding the feedback component as well as the feedback mechanism itself. 1. I am using the attached schematic as reference for my design. As per the LM2576 module data sheet, it can handle a maximum current of 3 A whereas I need the IC to handle at least 15 A...
  7. gumby4231

    Buck Converter with USB-C output

    I have a https://www.lattepanda.com/products/lattepanda-delta-432-with-win10-pro-activated.html single-board computer. For my project, I'd like to power it from a 12V tractor battery if I can. I also have the option of powering it via the JST ph2.0 4P 12V DC connector. I discuss this option with...
  8. D

    I don't know how to use a buck converter....

    you are suppose to be able to vary the output current of a buck converter. how do i vary the output current of a buck converter? i am just trying to make sure i know how to use a buck converter.
  9. K

    Buck converter will power LED's but voltage divider will not....

    Summary: Am seeking help understanding why when I take my battery (50V max 44 nominal; 15aH capacity; 12s5p) and attempt to step down the voltage that sometimes it works and sometimes not... Hi all, New to forum. Chemical engineer seeks help from electrical engineers... Thanks for reading...
  10. Sid55

    How to power up a DIY LED panel with a PC PSU?

    Thanks to anyone who likes to chime in and help out this newbie. :smile: I bought some CC CV buck converters to power my DIY LED panel project using a perfectly working PC power supply unit that was collecting dust inside a fairly old and unused PC but unfortunately the buck converter does not...
  11. Wrichik Basu

    Queries related to buck converters

    In a circuit that I am building, I have a rectified DC of about 22V, and I want to regulate this down to say, around 8V to 10V. Previously, I thought of using a voltage regulator, LM7808, as discussed here, but I strongly believe that a potential drop of 22V - 10V = 12V would produce a lot of...
  12. J

    Buck Converter (Step Down Chopper Derivation)

    Hi, I'm studying Choppers and I'm struggling with derivation of Buck Converter. As per equation 13.3 if I solve it ahead I get Vs D T - Vo D T = - Vo T + Vo D T Solving this ahead I get Vs (D T ) = Vo (-T + DT + DT) Vs (DT) = Vo(2DT - T) Vs D = Vo (2D - 1) Vo / Vs = D/(2D - 1) Not sure how to...
  13. Y

    Electrical Engineering - Buck Converter, Prevent Saturation

    Homework Statement I need help with part b- A buck regulator is supplied from a 12VDC source and outputs 5VDC at 4 A with a PWM switching frequency is 100 kHz. Answer the following then: a- Determine the continuous conduction mode inductance (L_CCM). b- Compute the inductance for the...
  14. Mzzed

    Understanding 'C Code' & 'No.' in Buck Converter Regulator Datasheet

    I have recently come across a datasheet for a buck converter regulator that uses the terms "c code" and "No." for certain capacitors but when going to the manufacturer datasheets for these capacitors they make no reference to any "c code" or one single number for a capacitor. If anyone could...
  15. Mzzed

    Potentiometer alternatives

    So a friend and I are building a power supply using buck converter. The buck converter is going to be using the adjustable version of the LM2678 switching controller that will regulate the output voltage by varying the duty cycle. The chip uses a voltage divider connected to the output voltage...
  16. D

    Problem with a buck converter: my error, or the device's

    Hello everyone, I am in the process of designing a buck converter. This is the regulator I have chosen. http://www.aosmd.com/pdfs/datasheet/AOZ1242DI.pdf The input will be 13V output will be from 12 to 6 volts (will be adjusted via a thermistor on the FB voltage divider R2) Now, the issue...
  17. B

    Buck Converter (Step Down) Help

    Homework Statement See attached sheet Problem with the buck converter circuit as in the diagram attached. The PWM is fed from a OP AMP in comparator mode, can we find the values of R1 and Vout. We have been supplied with the values of R2, the Duty Cycle of the waveform is 30%, and Vref which...
  18. P

    How to shut off Led on buck converter

    I am using a buck converter with a battery pack, for a usb charger. The issue is, is that the buck converter I have ( http://www.ebay.com/itm/DC-Converter-Step-Down-Buck-Module-7V-24V-to-5V-3A-5V-usb-output-power-adapt-/261030150117?hash=item3cc69bffe5:g:Q3UAAMXQTT9R0Qos ) has a led on it, which...
  19. P

    Can I Use Parallel Buck Converters to Achieve Higher Amperage?

    I have a ton of 1A buck converters, and have a 5A application in which i need to run. I do not want to order any new buck converters, because I already have so many 1A ones, and do not have money for any new ones. Each one can only handle 1A before it over heats. I was wondering if I could use...
  20. U

    Help with buck and boost converter

    Hi all, I'm new to power electronics, and somehow I still could not get the impact of switching frequency on voltage gain, output voltage ripple and inductor current. Additionally, how is the voltage gain affected when increasing load resistance? Thank you!
  21. P

    Charging Super Capacitor w/Buck Converter: Max Voltage Draw?

    If I am charging a super capacitor with buck converter, that is a 1 amp, 1-18 volt output, and the capacitor is rated for 2.5 volts, how do I stop the buck converter from feeding it more than 2.5 volts? When I attach the capacitor to my digital power supply, it starts charging, and the voltage...
  22. Chacabucogod

    Why is my Transistor Reducing Voltage in Buck Converter Modeling?

    Hi I'm currently modeling a 5-12Vdc buck converter, and just out of nowhere decided to put a transistor between the output resistance and the diode. Now, this transistor is always connected to voltage so it shouldn't do anything at all, it's just a closed switch. What happens is that the...
  23. jegues

    Buck Converter Design for PMDC Motor

    Buck Converter Design for PMDC Motor Introductory Notes: The design article followed in this post can be found here: http://my.ece.ucsb.edu/York/Bobsclass/194/References/NonIsolated/Buck/Buck%20Converter%20Design%20Demystified%20606PET25.pdf This circuit will be used for a motor controller...
  24. jegues

    Buck Converter Questions (DC-DC Converter)

    Homework Statement See first figure for lab attachment Homework Equations The Attempt at a Solution Hello all, I recently did a lab on buck converters and I have a couple a questions. See the figures attached for lab and my work. For Experiment 1: The measured quantities for part b)...
  25. L

    Buck converter inductor current at start up

    I am trying to understand the inductor current ramp up to steady state in a buck converter. I don't understand why the inductor current slope is not steep in the beginning. Let's say Vin=12v, Vo desired across the capacitor is 5V. Switch turns ON, Inductor current ramps up. Switch...
  26. G

    High Voltage A-synchronous Buck Converter (100V -> 28V)

    Hi guys, I'm new in here and hope I could get some advices. I am designing a 100V-28V DC-DC Buck converter (as per tittle) and has successfully tested on breadboard. The problem is when I've transferred everything to the stripboard, the circuit does not work. This is confusing to me...
  27. D

    Buck converter in continuos mode

    Hello, I don't quite understand the buck converter in continuos mode ... looking at the graph for inductor current on wikipedia, at t=0, there is a nonzero inductor current, Imin ... how is this possible when the inductor current cannot change instantaneously (assuming it starts at zero...
  28. F

    Buck Converter High-Side Switch

    As a hobbyist I have had an interest in SMPS power supplies for quite some time, but have never gone past casual study of them. I understand the theory, but have difficulty with the actual implementation of things like a high-side switch mechanism for a P-Channel Mosfet. My goal is to...
  29. M

    Solving Compensator Circuit for Synchronous Buck Converter (SBC)

    Hi All, I'm working on my final year project on synchronous buck converter (SBC). In this project, i have to use an adaptive gate drive (AGD) and a compensator to switch on both of the SBC switches. The AGD is connected to the second switch (Low side switch) of the converter meanwhile for the...
  30. Z

    Design a Buck Converter with Low Power Losses

    how to design a buck converter that will have less power losses
  31. J

    Current Regulation on a DC Buck Converter

    I'm an entry-level engineer, and I have a design question for the forum: I'm designing a multiphase buck DC/DC converter which will convert roughly 65VDC to 52VDC at up to 150A. I'm using 4 phases, so inductors, etc will be designed to about 40A/phase, MOSFETS will be paralleled for less...
  32. E

    Boost Chopper or Buck converter?

    Ok, first post so be nice guys! I've designed and simulated a design for controlling a brushed DC series motor in OrCAD and it does what i was aiming for it to do. Which is to step down voltage to an average of 50% with duty cycle at 50% etc. I thought I had it all figured out but...
  33. I

    Design cascade buck converter

    i want to design cascade buck converter,but I'm kinda confuse about the controller that i'll use for the converter...there are 2 options, i make the controller independent from 1 converter to another, or i just make the controller dependent, it means that i have only 1 controller for all...
  34. B

    How to Drive a P-Channel FET in a Low Voltage Synchronous Buck Converter?

    I am trying to develop a circuit to convert 5-18Vdc, 100ma max to 0.4Vdc, 400ma. I am working on a synchronous buck converter design but I am finding limited resources on a discrete design. All of the buck converter IC's I found do not go low enough and have inadequate efficiency when they are...