A switch-mode power supply (SMPS) switches been fully-on and fully-off states quickly to maintain voltage regulation. They offer lower power dissipation and run cooler than linear regulators that continually dissipate power through a transistor.

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Help with designing negative part of Dual-Sided SMPS

For a project of mine, I'm trying to make a dual-sided SMPS that has independently variable positive and negative supply rails, current limiting, short circuit protection, etc etc... My current plan ...
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43 views

How to estimate max current draw from an unknown PSU? [on hold]

I have a couple of PSU boards from Sony PS2 consoles. They convert 230VAC to 12VDC and would be useful in a couple of my future projects. Unfortunately there's no information how much current they ...
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71 views

How can a Ultralow Voltage Step-Up converters start up?

I've read about step up converters working from unbelievably low voltages (20mV), namely the LTC3108. How can circuits even start at those low voltages? Diodes, FETs and BJTs shouldn't switch at ...
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3answers
223 views

Why do we need bulky filters at the input stage of SMPS designs?

I usually see costly and large filters at the input stage of switch mode power supplies. Isn't the AC signal already filtered by the large capacitor (the 100\$\mu\$F one in this example) after the ...
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97 views

3v3, 12v Smps: “Design ok!” “Pcb ok!” Why not stable? Please Help

Im working on a project and i need 3v3,5v and 12V in this. I though smps circuits would be better than Linear Regulators. So i choose LM2676-adj IC. I designed schemetics for 3V3-3A SMPS and 12V-3A ...
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56 views

Dual Power Supply Switch?

So the question is short, how do i connect a single switch to a circuit that has a dual power supply (+/-) connected to it? Or do i have to use an special kind of switch?
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80 views

Via's in switch mode power supply

I'm using a TPS54386 and currently designing a PCB layout. The data sheet says to avoid via's within a certain loop; I was wondering what would happen or if anything would if I went ahead and placed ...
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66 views

How does reverse leakage current of a Schottky diode come into play with a SMPS?

Looking at diodes for a low power switch-mode power supply I'm designing. I'm not quite sure what the reverse leakage current value is, or if it's relevant in the component selection.
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38 views

TPS54383 switching regulator components.

I'm trying to build a switching regulator using the TPS54383 dual output regulator, Now I've got most of the components and schematic figured out here. pdf Except the inductor's and diode; I'm ...
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83 views

Why do we compensate PWM controllers?

I have been studying switch mode power supplies for a while. I have understood the working principle of several common topologies But there is a detail in the control circuit structures which I still ...
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89 views

Why the voltage drop is so high in my Half-Bridge SMPS?

I have been building an offline Half-Bridge SMPS of about 300W with a friend of mine. We need a variable range from about 10V to 30-35V. We finally got it working and we could achieve 10A at 30V. The ...
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53 views

Set ground reference of a 5v DC power supply to the middle of a 24v DC power supply

I have 2 isolated AC/DC power supplies. one generates a regulated 5 volt power supply and other generates a 24 volt power supply as you can see in the picture below: I also have designed a circuit ...
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95 views

How reliable or trustworthy are LTSPICE demo circuits?

I'm looking at a few switching power supplies and one of the demo .asc files for the particular controller I was looking at really seems to fit my requirements. Can I use their schematics in designs ...
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106 views

PSU not providing enough current

I am using a computer PSU to power a 92 watt(12V 6A) peltier device.The PSU has a rating of 450W,it has got 2 rails of 12V ,one delivering 15A and another delivering 16A.However when I connected my ...
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66 views

What is the purpose of a Zener diode added to the output of a SMPS?

I studied circuit diagrams of some computer ATX power supplies. Some of them have got a Zener diode at the very end of 5V stand by line. The picture shows endpoint of the circuit - the SMPS is on ...
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30 views

Is a 100K+ 200vdc 100ma smps for audio possible?

Ideally a variation on this at a higher switching frequency. Would this board need to be changed very much to have it switch at 100K at 200v/50ma? http://desmith.net/NMdS/Electronics/NixiePSU.html ...
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25 views

Switching mode power supply ground island

I'm currently designing a 4 layer PCB with multiple buck converters on it and I would like to ask for suggestions regarding the best possible grounding scheme. To avoid that these converters ...
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45 views

Convert a device that is powered by a 12V 2 amp ac-to-dc SMPS to a battery powered device

I have looked up my requirements in all possible sources (Google, StackExchange, DiY boards, etc.) but I have not been able to find a clear answer to my problem. What I have is a device that needs ...
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76 views

Can I build a high-frequency SMPS choke out of an arbitrary coil of wire?

Suppose I want to build a boost converter that runs at 100 kHz, with an input voltage of 600VDC and an input current of 100 amps. (This is hypothetical, I know the semiconductors involved would be ...
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46 views

SMPS Inductor oversized vs properly sized

I am working on an SMPS for boosting an input voltage to drive a single string of LED's. The input voltage range is from 18 to 32 volts. The output voltage needs to be about 60V and the drive current ...
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1answer
91 views

SMPS regulator blows up, could it be a layout issue?

I have a curious problem which I have been trying to solve for a few days now and I just can not understand what is going on. I have designed a SMPS which takes 24V input and outputs 5V (which is ...
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78 views

Switching between two output voltage

I have a sensor which generates signal in range of 240mV to 940mv. Now, I use amplifier of voltage for my sensor, which generates output signal in range 350mV to 1000mV. I used rail-to-rail ...
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37 views

half bridge … transformer and devices overheating

I have made a SMPS for Audio Amp with the following Spec Input Voltage range - 100 - 270VAC Line frequency - 50Hz Output Wattage - 550W Output Voltage - + - 50V @ 5.5A These are very basic ...
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34 views

Why is the output voltage of the forward converter is dependent on the duty cycle?

The Wikipedia article "Foward Converter" claims that the output voltage of the forward converter is $$ V_{out} = D \times \dfrac{N_s}{N_p} \times V_{supply}. $$ Where, \$D\$ is the duty cycle. Here ...
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53 views

Connecting devices powered by separate SMPS without common ground

I have a power over Ethernet design using the SI3402 PoE PD chip to generate 3.3v for a pic 18F67J60. The switched mode voltage converter in the SI3402 is a little unorthodox in that it switches Vss ...
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51 views

Switching power supply using faraday cage and EMI protection?

Several switching power supplies in the market use this kind of cages to protect the circuit, however, i have this question, A) Is this used as a faraday cage due to the high frequency used by it? ...
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75 views

SMPS: What is current mode instability (aka “sub-harmonic oscillation”)?

In peak current controlled switching power supplies, there is a phenomenon called “current mode instability” aka “sub-harmonic oscillation”. What is that? Can't seem to get a good explanation of ...
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188 views

What is the advantage of a switching over a linear power supply?

I want to build my own switching power supply. I already know how to make a 10 Ampere Linear supply, and I'm wondering if I should bother. What do I have to learn to do a switching supply? What makes ...
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69 views

Info on transformers? Where to find?

I'm quite often taking things apart to salvage the parts and use them in my projects. Right now I'm taking apart an old PC-power supply for a switch-mode lab-supply project. The power-supply in ...
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68 views

Capacitors vs buck/boost converters

I'm trying to drive high power LEDs with a laptop power supply, and wondered if I should use resistors to limit the extra current, or something like this to limit the current. If I did use that ...
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49 views

Switching Power Supply makes speakers hiss

I have a computer with a 5.1 soundcard, that I'm using to run a standard PC 2.1 setup (Corsair SP2500) on the main audio output, and two rear surround speakers I had laying around. The speakers in ...
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46 views

Using bench power supply to drive ex-cordless driller

Ok, so I perhaps naively thought I was the first person to ever think of this - go figure. Anyhow I managed to get my hands on a couple of cordless drillers which have an expired battery and thought ...
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78 views

Simultaneous Buck-Boost or Flyback Regulator - Help Selecting Chip [closed]

I have been trying to find a switching DC power supply that outputs a constant voltage of 12VDC, given a variable input between 4V and 25V. It's to my understanding I'd need a buck-boost converter, ...
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116 views

Boost regulator: Unexpected output voltage

I just finished setting up an LM2577 as a boost converter, and have run into some unexpected issues. For starters, here is the recommended "typical application circuit": My application circuit is ...
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1answer
74 views

Strategies for powering an ATtiny micro controller and 40W peltier from mains

I'm trying to power an ATtiny1634 at 5VDC and a 50W peltier element at 12VDC. The microcontroller will, amongst other things, turn on the peltier via a 5VDC non-latching relay. I want to use an ...
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90 views

DIY wifi radio radio NOISE!

I am building a mono, internet enabled, WiFi radio and I have a problem. I am running into what I believe may be a grounding issue. When I turn the system on, I hear all kinds of noise coming from ...
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75 views

Voltage drop when servo activates

Background This is a follow up to an earlier question I asked - I have an ATmega2560 running a number of sensors and servos. There are two separate SMPSs running off a single 12V battery, one ...
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35 views

Troublshooting noisy smps

I had a working design of a buck switching regulator based on a TPS62125. It worked fine, with minimal (<100mVpp) noise. I made some changes to my design, seemingly unrelated to the switcher. The ...
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238 views

Where can I learn Switched Mode Power Supply Design? [closed]

Recently I've had terrible luck buying those little DC-DC boards from China off of eBay. We've been trying to build projects where we have some sort of wobbly input DC off of a car or solar, ...
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108 views

Linear regulated supply from noisy input voltage

I have been working to redesign a faulty circuit board. One of the problems I have identified is the power supply on the board. The input voltage is nominally 13.8V DC from an AC switchmode ...
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68 views

How to create a 120V-175V Variable Frequency Generator

I am dealing with a system that requires me to drive a capacitive load at 120V-175Vrms, AC square/sine wave at two frequencies: 50Hz and 2000 Hz @ Ipeak = 100mA. I am currently trying to find the best ...
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51 views

LTC3603 Regulator shorted out

Basically the LTC3603 seems to have internally shorted itself. I'm using a auto generated circuit, realised with Eagle CAD. I'm trying to design a high current switching power supply with the ...
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94 views

Is this Half-Bridge waveform right?

This started with my question here there is no need to read it, I put it here for additional info. I'm trying to drive two MOSFETs in Half-Bridge topology and I finally could get the pulse ...
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59 views

Best Topology For High Voltage Isolated DC-DC converter (12V to 240v , ~0.2A)

I have been searching for a design that can serve as a basis for a supply as above, with the following design requirements. It seems most designs I can find are for low power (<10W) Flyback ...
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117 views

Generate 10A for stress testing

How could I, a cheapskate hobbyist, generate large currents around 8–10 Amps to run through a short circuit? That is, the objective is to stress test a very low-resistance circuit going ...
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93 views

Low noise voltage regulation

I have a circuit which currently runs off of either a 12VDC wall wart adapter, or it falls back to a 9V battery if the wall wart adapter is not connected. My circuit currently uses a chip which ...
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1answer
58 views

Flyback converter current flow?

If you look at the flyback converter circuit above, the current only flows in one of the coils at any instant of time. What stops the magnetic field generated by the coil in series with the MOSFET ...
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118 views

What's wrong with this IR2110 pulse transformer driver?

I'm trying to drive two MOSFETs through a pulse transformer. I'm using the "Power Supply Cookbook – Second Edition" book from Marty Brown. According to the book the formula to calculate the number of ...
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1answer
48 views

Battery discharge rates and current limiting

In a project I am building, I have a CVCC to control the current and keep it where I want it. (The circuit would definitely use more current it I didn't use the CVCC.) The problem arises because when ...
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1answer
127 views

Do AC inverter H bridges ever get driven this way?

There's a google competition going on at the moment called the little box challenge. It's to design a very efficient AC inverter. Basically the inverter is fed a DC voltage of a few hundred volts and ...