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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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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166 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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61 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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59 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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37 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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41 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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65 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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103 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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63 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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61 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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63 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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1answer
30 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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216 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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98 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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52 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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44 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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2answers
75 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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44 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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116 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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83 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
47 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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2answers
76 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
34 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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108 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 ...
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68 views

Critique of SMPS layout

Can you guys provide some feedback on my layout for this TP562200 buck regulator? I'm using it to take a ~12V and drive a servo. The supplied resistor values should provide about 5.1V, which is within ...
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95 views

SMPS design with BUCK converter [closed]

I want to design the SMPS with the following specifications- 5V DC,5Amax,1Amin 12V DC,5Amax,1Amin using BUCK converter. Vin DC=24V
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38 views

What does voltage output from an SMPS look like when inductor is saturated?

I've built a buck smps around the LM2734X. This is meant to power servos, running off a 12V battery source. Scoping the +5V line using smaller servos, I see a stable voltage, with a peak to peak of ...
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74 views

How to Mount Power Supply to PCB

How can this 5V 3W power supply board be mounted and electrically connected to a custom designed PCB? Or will it be better to get this power supply board instead due to the right angled pins ...
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1answer
28 views

best way to adjust/set SMPS comp / compensation parts

I’m having difficulties with settings the right values for the comb / compensation for some SMPS circuits I’m working one. Is there a good way to set them right? To make sure of stable operation in ...
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95 views

Power supply ringing when servo activates

I'm running a servo from a 12V -> 5V buck regulator. The servo has a stall current of about 500mA and a nominal operating current of about 200mA. Here's a scope reading from when the servo starts ...
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2answers
141 views

How does R5 bias the zener in this SMPS circuit?

In the description for the circuit below from this data sheet for TNY268 off-line SMPS switcher, it says R5 is used to ensure that the Zener diode is biased at its test current and R6 centers ...
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87 views

How to make a 50V regulator?

How do I regulate the output coming from a 50V transformer? At the filter's output, the transformer has 50*1.4142=70.7 volts. But this voltage of course drops as a load is applied, since the filter ...
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43 views

Why would a buck regulator continue to draw current when EN was off?

I've got a board with two regulators on it a TPS62125 (to power the whole board) an LM2734 (to power servos) For the purpose of this test, the EN pin of the LM2734 is pulled down to ground with a ...
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39 views

What controller for a 400W AC-DC SMPS?

I would like to build a big AC-DC SMPS. I built a little one based on ST's VIPer22A. This is a nice little IC that can give up to a couple watts (my design was 5V 1A). It was easy enough to design ...
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169 views

LDO vs switching regulator

We've currently got a PCB that needs to power a modem and a microcontroller. The PCB is powered via a battery (12V - 30V range). The modem and the microcontroller have separate power lines. The ...
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1answer
54 views

Oscillation on an 4 phase 12 to 24V 20A boost inverter

Oscillation on an 4 phase 12 to 24V 20A boost inverter I’m using 2 pieces of LTC3787 to make a 12-24V inverter. I made a 4 layer board from it to have enough ground to make sure all will be stabile. ...
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131 views

SMPS gives “electric shock”

I built the following circuit, a reference VIPer22A circuit. It works fine but I have a little problem. It gives an electric shock on the secondary side. It's not a "line" shock (sticking your ...
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2answers
62 views

Troubleshooting a power issue on a DIY board

I built a board that combines a number of sensors, an ATmega2560 and a TPS62125. The board worked, I was able to measure 3.3V coming out of the buck regulator, and was able to program the ATtmega via ...
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65 views

What is too noisy for a switching power supply

I built a buck converter to take a ~12V battery source down to 3.3V to power an atmega2560 running at 8MHz. Here's my scope output looking at VCC when it's running (at this point, I'm measuring an ...
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3answers
328 views

Why would a switching power supply fail with a battery supply?

I have this power supply circuit I have been using for a couple of years: I have put it on a lot of boards, and ranging input voltages up to 50 volts (as long as the capacitors are rated that ...
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1answer
54 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: ...
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45 views

How to fix current leakage in a laptop at the mains? [closed]

See this previous question: current leakage in a laptop Kind of reopening this case, I expect that some fix at the power supply side would fix this, like connecting the neutral with the ground, OR ...
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21 views

How to rectify the power line for leakage current based electrical shocks? [duplicate]

In May 2014, I had purchased Samsung LCD TV with two pin mains cord. I used to get electric shock like feeling when I touched the metal body part of it or the HDMI port (any other connected ungrounded ...
4
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1answer
79 views

Do I need to isolate the output voltage feedback in SMPS?

I almost finish with my Half-Bridge SMPS design. I'm now designing the output voltage feedback to the controller stage. The controller stage drives both MOSFET transistor through an isolation ...
2
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1answer
73 views

Where can I find a stable AC to DC switching power supply?

I've purchased multiple 3V switching power regulators form Amazon and they all have spikes in the ripple. Here's an O-scope capture: The spikes increase frequency depending on the load. Are these ...
3
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3answers
172 views

Inductor selection for a switching regulator

This is somewhat related to this question, but hopefully a bit broader. I'm selecting components to fill out an lm2734. This regulator will take a 9-12V (11.1V nominal) input down to 5v @ 1A max. ...
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1answer
92 views

How to the calculate the value of capacitor placed in series with transformer to avoid flux walking in a buck converter? [closed]

The dc value of current in primary increases(in -ve direction) as time passes, so I need a capacitor in series with transformer, but don't know what value capacitor should I use. filter capacitor = ...
3
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1answer
95 views

Transistor Level Shifting in Buck-Boost Converter

Ive been reading some of the LT application notes on Jim William's Analog Circuit Design book, and there's something I don't quite understand. I'm attaching a scan of the circuit in question. The ...
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57 views

Weird computer SMPS issue

I am using a off the shelf 550 watt computer tower SMPS to run my 3D printer. It's imperative that this power supply be robust to ensure that my printer doesn't go haywire or turn off mid-print. I ...
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3answers
215 views

DIY current-limited 40A+ power supply to emulate LiPo batteries

I want to do some experiments developing brushless DC motor control hardware, and maybe wiring my own motors for my own edification. LiPo batteries aren't convenient enough, and I want ...