Questions tagged [buck]

A non-isolated DC-DC converter topology which outputs voltage less than or equal to the input voltage

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11
votes
3answers
11k views

Low side N-Mosfet buck converter

I often see schematics of basic buck converters. The majority of these schematics use a P-Mosfet as high side switch. Why is this design preferred over a low side, N-Mosfet buck converter? simulate ...
2
votes
2answers
565 views

How to sketch the Bode diagram of the output filter of a Buck converter?

I'm trying to figure out the Bode diagram of the output filter of a Buck converter: simulate this circuit – Schematic created using CircuitLab Vout is ...
2
votes
2answers
880 views

Is this a viable mini wind turbine setup?

I'm going to build my first wind turbine. I have already constructed the prop, 5 blades 50cm long from PVC pipes. I've searched for a decent sized motor and charge controller. The turbine will be ...
2
votes
1answer
2k views

Relationship between switching frequency and controller's crossover frequency in buck SMPS

Context: tuning the control loop of a buck SMPS. I specicifally have a TI TPS40200-based circuit in mind, but I think this applies to SMPS design in general. Quoting from Type 2 compensation network: ...
1
vote
1answer
301 views

Is there a good topology for splitting a DC power supply from a few LM2576 and LM2577?

So, this isn't the most serious project, more of a toy/hack, but I have a some LM2576 and LM2577 and I wanted to see if I could somehow get an adjustable dual rail (bipolar) supply out of them, for ...
0
votes
1answer
1k views

Multiple Input supply switching

I'm looking into designing a power supply for an RPi that can take both USB and battery at the same time, but only pull power from one of the sources. I'm not quite sure how to go about it, I was ...
9
votes
3answers
18k views

Calculating size of cap & inductor for buck convertor

What is the idea of choosing inductor & capacitor value for buck DCDC convertors (no specific part number, in general)? I've tried random one with low resistance, and it kinda works, but want to ...
10
votes
2answers
950 views

Is this normal Buck Regulator behaviour?

I recently got around to trying out buck regulators, my results weren't what I was expecting though. For one the ripple voltage seems a little high to me, It's about 800mV with no load and goes up to ...
17
votes
6answers
12k views

Why do buck (step-down) switching regulators require an inductor and diode?

So, I understand, at least at a basic level, the method of operation of switching converters, both buck and boost. What puzzles me, though, is why buck converters in particular aren't simpler. Why ...
15
votes
5answers
21k views

Is it ok to connect the output of buck regulator in parallel?

I am using MCP16322 buck regulator powered from 12V and outputs 5V and 2A. Is it ok to connect the output of two of these in parallel? Does connecting the outputs in parallel mess up the maximum ...
8
votes
3answers
1k views

Critique my SMPS buck design

I'm using an LM2734 buck regulator to get +3.3V at 400mA. The datasheet is unclear on how to lay out the supply, so I tried to follow some common sense, keeping all power traces short where possible. ...
7
votes
3answers
3k views

Can there be “too much” capacitance on a buck regulator output?

I've an MPM3610 buck regulator module with an integrated inductor of 0.47 µH and a fixed internal compensation. It employs constant-on-time regulation. The datasheet gives some application ...
6
votes
3answers
2k views

Snubbing DCM (nonsynchronous) Buck converter

FINAL UPDATE: I've posted an outcome report below. I'm very satisfied with how this has come out and I learned a lot in the process. More details and before/after shots in the answer below. Thanks to ...
6
votes
1answer
1k views

USB-C Power Delivery with a buck converter

Following on from my previous question: The project I'm designing requires a peak current of 5V @ 6A. The average current draw will be more like 2A. The reason I'm looking into USB-C is that I want ...
2
votes
3answers
5k views

Buck converters- No Load condition

How exactly do buck converters work under no load condition? The capacitor voltage will try to charge up to the peak input voltage, with no load connected across it to discharge. How to avoid this ...
6
votes
1answer
329 views

Vin: 2-36, Vout: 4.2. Should I use step-up, followed by step-down, or SEPIC?

My application has a small device, which draws about a watt, and is powered through a small dynamo, backed by a battery: The dynamo generates 33 volts at maximum speed, close to L6902's max input ...
3
votes
1answer
508 views

Is it useful to think of SMPS input capacitance as part of an LC filter?

I'm at the stage of learning about switched-mode power supplies that I'm focused on understanding the role of input capacitance. Just for background, I'm working with a buck topology for this ...
2
votes
2answers
1k views

switching noise from ltc3780

I have currently built a buck-boost converter using LTC3780 on a breadboard following this deisgn. The circuit is calculated and designed to accommodate the input voltage given in the schematic. I ...
1
vote
1answer
93 views

Conducted EMI of buck converter is too low even without filter

I have simulated a 48 V to 12 V buck converter with LISN in LTspice. However, CM and DM EMI is way below CISPR limits. I want to simulate a real world converter. How can EMI be increased? [2]
0
votes
3answers
619 views

using buck converter

I have a 6V 3AMP power supply and I wanted to reduce the voltage output to 5V 3AMP. I saw buck converted on ebay of the following spec. Can i use it to step down 6V to 5V without losing Ampere? or ...
0
votes
1answer
5k views

LED bulb can not start properly (BP2832 based)

I bought several LED bulbs about 2 years ago, and now before turn LEDs steady on, some of them flash for some time. Frequency of flashing may differ from bulb to bulb. After some time flashing, they ...
0
votes
0answers
92 views

Help refining a current control loop circuit

As a follow up to this question. (Sorry if this linking other posts is wrong. I'm new to forums) Will this design for an XHP70.2 LED Driver with arduino control work to the params specified? TL;DR: ...
0
votes
2answers
318 views

LED bulb redesign

As a follow up to this question I decided that it is time to see how should I utilize failed LED bulbs. There're 5 of them now, however in different condition - one does not start at all, some start ...
17
votes
1answer
15k views

How important is self-resonant frequency for an inductor when used in a fast (~3MHz) buck SMPS?

I'm using the LM2734Z, a 3 MHz buck regulator. It's really fast which means it has a small inductor. One of the things I'm wondering is how important is the self-resonant frequency of the inductor? I'...
15
votes
4answers
11k views

How do I select the correct inductor value for the following buck regulator?

First of all, I suck a bit at math, and I'm no electronics genius, so the stuff I do is for fun and for learning purposes... I'm working on a buck converter circuit to convert my USB Vbus 5V to 3.3V. ...
13
votes
1answer
3k views

Noise problem with buck/boost switching regulator

I am designing a electrical device for a research project (I'm a PhD student, but unfortunately not EE!). More info on the device can be found at http://iridia.ulb.ac.be/supp/IridiaSupp2012-002/ The ...
12
votes
2answers
5k views

What is the purpose of using MOSFET instead of free-wheeling diode in Buck topology?

(Source) I usually see Buck circuit models in which a MOSFET is used instead of a free-wheeling diode. What I understand from the Buck topology is, when the upper MOSFET is off, it doesn't matter ...
9
votes
3answers
4k views

SMPS PCB Design Critic

Oldest versions of this post can be viewed through this link. This is my re-designed layout. What is your view again? 10-32V to 5V 1.2A SMPS Buck Regulator Design. The IC is IFX91041 from infineon. ...
5
votes
2answers
1k views

Buck converter operation

I have been reading about the buck converter and have also referred to the various online resources like here. In the above circuit, as I understand, when the switch closes, current starts to ...
6
votes
1answer
861 views

Loop compensation design of buck converter

I am trying to design loop compensation with type-3 error amplifier for a buck converter. I'm a student and very inexperienced in this subject. Please bear with me. Here is the general procedure ...
11
votes
2answers
2k views

Routing a buck/boost DC/DC converter

I need some help with the layout of a power supply. I botched the first two iterations as I do not have the necessary experience, and I would like to avoid another costly run. For the sake of ...
10
votes
2answers
1k views

Buck converter, squeaking/whining inductor

I have a problem with my homemade buck converter. It is based on a TL494 control chip with my discrete MOSFET driver. The problem is that my inductor squeaks and whines, when the output current ...
10
votes
4answers
6k views

Remove audible noise generated by buck converter

I'm dealing with a buck converter using an ISP452, an inductor and a capacitor to act as a buck converter driven by a PWM signal coming from a microcontroller. Some part of the circuit is producing a ...
9
votes
4answers
2k views

Boost or buck regulator for battery life?

I want to make a wireless sensor node that will run at about 2.5v. I am trying to decide between running 3 alkaline batteries in series with a buck converter or in parallel with a boost converter. I ...
9
votes
1answer
2k views

Switching regulator output is unstable

I have a problem in buck regulator. I'm using L4970A to make a buck regulator with a variable output that can be adjusted using a potentiometer. Output is becoming a ramp when I set the output ...
8
votes
2answers
8k views

How to control a buck-boost converter circuit from a microcontroller?

I'm reading about buck-boost DC-DC converters lately and one thing is still not very clear for me. Most of the converter ICs that I've seen have a feedback loop input pin. For example LTC3780 requires ...
7
votes
4answers
5k views

Efficient low-power buck (step-down) regulator IC for Li-Ion - 3.3V conversion?

It's not easy for electronics novice to find good element base, so I hope this suitable question. Requirement: Efficiently power a lean, 3.3V-based MCU design from a Li-Ion battery. "Efficient" ...
3
votes
5answers
7k views

How to power a GSM Modem from a Li-Po battery?

I want to integrate an AirPrime SL6087 GSM modem into a design, this is my first try at working with a GSM module. The datasheet states that the modem draws 2A for 1mS every 4mS (max) at 3.6V, the ...
2
votes
2answers
4k views

Resonant Frequency of LC Circuit in Switching Converter

Why do we set resonant frequency of LC circuit in a buck converter to be less than 10% of Fsw? For example, if Fsw is 300 kHz, why should resonant frequency be around 30KHZ. I am guessing it is due to ...
1
vote
2answers
778 views

Peer Review of Buck Converter

The only limitations I can think of are: Comparator/Schmitt not gate output swing time, and Transistor switching time simulate this circuit – Schematic created using CircuitLab BTW, these are ...
15
votes
9answers
9k views

For a small Vin-Vout difference, is it worth using an LDO vs a buck regulator?

I want to step down 5V to 3.3V at around 250mA. As far as I see it, there are two options to consider: Buck: more space, higher cost LDO: less space, lower cost, more difficult to remove heat(?), ...
7
votes
4answers
6k views

Why does this buck converter output such low current?

I'm making my first attempt at building a buck converter, as a constant-current supply for a 700ma LED, from a 5V or 12V supply. I have it working with the parts I had on hand, at about 88% ...
6
votes
3answers
3k views

Schematic for common buck/boost converter designs

Does anybody know the schematics of these common LM2596 buck converter with current adjustment and buck-boost converters from ebay? I know I can easily buy it cheap but I like making my own modules ...
6
votes
1answer
3k views

Effect of using two buck converters in series

Are there any limitations of connecting two non-isolated buck converters in series? Just taking the output from the first converter and connect it as the input of a second converter to produce two DC ...
6
votes
7answers
6k views

How to reduce MOSFET heating in Buck Converter

I have designed this Buck Converter which convert 60VDC to 12VDC at 10A. Switching Freq 100KHz. Facing MOSFET too much heating issue. MOSFET ON time and OFF time is decided by a UC3845B based circuit. ...
6
votes
2answers
4k views

Behavior of Boost and Buck Converters

I have a couple questions about boost and buck converters. First, do they try to hold the output voltage constant, or do they alter the input voltage by a constant factor? For example, if I change ...
5
votes
1answer
935 views

Is it possible to get a high efficiency buck-boost converter by switching between the two?

Many buck-boost converters work by boosting to an intermediate voltage, then bucking to the desired voltage. What if instead, it had a separate buck and boost section in parallel, and switched between ...
4
votes
1answer
588 views

Can a synchronous regulator “chirp” in burst mode?

I'm looking at (the millions of) buck regulators available for a project where the board will be a host board for a Gumstix Dual Cortex A9. This can pull quite a bit of current at maximum so I was ...
3
votes
3answers
6k views

Not getting stable voltage output with DC-DC Buck Converter

Coming from a computer science background, I'm new to electronics and my first post here. I'm working on a hobby project with the intention of designing a PCB eventually and the first step is to ...
3
votes
1answer
176 views

Techniques for Filtering a Noisy Buck Converter

I have built a buck converter on the TS30011. Unfortunately, I am getting terrible noise on the output. External Parts Used: Inductor Output Capacitors I have been analyzing my design and have ...