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Questions tagged [switch-mode-power-supply]

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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1answer
71 views

Two server powersupplies in a row dangerous?

I have two server PSUs from HP which can output 12V with 1200W (HP DPS 1200.) My goal is to obtain 24V by chaining the outputs of the two units. I have modified one of the PSUs so that the negative ...
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22 views

Analyzing and Improving Power Filtering

I have a wireless radio NRF24L01+ hooked up to a 3.3V LDO voltage regulator. The battery that powers the LDO also powers high current motors. The NRF24L01+ already has 100uF capacitors near the device ...
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1answer
51 views

Can we apply maximum power transfer theorem to SMPS rectifiers?

Thevinin and Norton equation simplifies BJT and MOSFET analysis leading to the hybrid pi models. Can we apply the same concept while analysing an AC-DC Converter with PFC and PSFB full bridge topology?...
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55 views

Understanding Low Power Solution

I have a device that is powered off of a large battery. This device has peripherial ICs on it that consume power. Right now I have the input voltage through a switching regulator to 5 volts and then ...
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1answer
41 views

Series regulator noise levels

When using multiple regulators in a chain, is there noise added to the input by the regulator? If I have a SMPS feeding an LDO, and then another SMPS after the LDO. Is the ripple or noise added to ...
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32 views

MFRC 522 not working when using with relay module

I have a circuit which basically have to link up to MFRC 522 module, Arduino Nano and also the relay 2 channel module. See below for the basic schematic. simulate this circuit – Schematic ...
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1answer
86 views

How come PC/laptop power suppliers have much higher wattages per physical size than laboratory switching power suppliers?

This 2.2 kg 1000W BeQuiet BN213 ATX power supply is able to provide 12V 83A (no typo. Eighty-three.), which is around 1000 W. This huge PS900W (60V15A 30V30A 15V60A) bench power supply weighs 5 kg ...
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1answer
60 views

What function does the Inductor and Resistor serve?

The image attached is the circuit of a SMPS with primary side regulation. I am not sure about the purpose of inductor L1 and resistor R5 in this circuit. I figured it has something to do with noise ...
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148 views

Switching Power Supply - Type of MCB for Inrush Current

it's regarding this PSU from Mean Well: https://www.meanwell.com/Upload/PDF/LRS-350/LRS-350-SPEC.PDF It has a 60A inrush current. My lighting circuit (1.5mm2 wiring) is tied to this PSU supplying ...
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61 views

Back powering a switching regulator

It is pretty standard practice to clamp a signal to Vcc by using a diode and resistor. However, when this happens, some small amount if current (maybe ~50mA) is flowing back into the Vcc line. When ...
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23 views

spike in the Full bridge SMPS

I have a full bridge SMPS and I am measuring the voltage across the output´s diodes on the secondary side. As you can see the voltage spike changes by changing the output current, for example at zero ...
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1answer
59 views

Switching Power Supply - Inrush Current, Input Current, MCB

I am getting several PSUs (LRS-350-24) from Mean Well. Here's the specs: https://www.meanwell.com/Upload/PDF/LRS-350/LRS-350-SPEC.PDF 1) The input current is stated to be 3.4A/230VAC at 88%. 350W ...
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1answer
31 views

LTC7813 buck-boost IC max output power

I am developing a power supply for a 24V 10A BLDC motor, which has to work with car and truck batteries (12V-24V). The real thing is that those batteries never have 12V nor 24V, instead, they could be ...
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1answer
102 views

Boost converter from 0.3 V to 12 V

This query is for a college project. The Source can give 0.3 V to 0.8 V. Need to boost the voltage to 12 V, so 6 x NiCd batteries can be charged through LM317 CC charger. The converters available are ...
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222 views

Designing switch mode power supply (SMPS)

I've been trying to make a SMPS for sometime now but I can't get it to work. In my design it keeps killing the MOSFETs once I short the output with a thin wire that doesn't let more than around 20&...
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1answer
79 views

What are these soldered/un-soldered dotted-shapes? on the traces which don't have soldermask?

Please look at this image(see the soldered/un-soldered dotted-shapes which are identified by arrows). This circuit belongs to a laptop adaptor. What are these soldered/un-soldered dotted-shapes? As ...
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4answers
566 views

Why are these traces shaped in such way?

Please look at this image(see the PCB traces within the circles). This circuit belongs to a laptop adaptor. What are those parallel soldered-traces on the PCB traces? Why aren't they soldered to ...
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36 views

Dual Rail Switch Mode Power Supply Filtering

I'm looking at the datasheet for a dual rail SMPS I plan on using for analog circuits, and I'm wondering about how to interpret some recommended filtering circuits. I understand a simple filtering ...
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76 views

Why does this laptop adaptor have two metal shields with different thicknesses?

Yesterday, I opened my laptop adaptor to learn something. First off, faced to this kind of shielding: There are two shields that cover the circuit. A thick shield which is covered by a thin shield ...
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2answers
97 views

Backup power supply using capacitors to help esp8266 run for 3-4 seconds after power failure [closed]

I need to make a circuit with introduction of capacitors in parallel with input supply of esp8266(3.3Vdc) to run it extra 3-4 secs after power failure, Is it possible to gain extra 3-4 secs just ...
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1answer
77 views

Combining non-isolated switch mode power supplies in parallel into a single supply

I'm trying to combine several SMPSs each having a ~350VDC output @100mA each. Background: Purchased an unused batch of small DC->DC SMPSs in good industrial quality. Unfortunately they're too weak ...
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2answers
84 views

How inverted buck-boost Boosts & Bucks

I am struggling to see how the "inverted buck-boost" converter works the same as a "4-switch buck-boost" converter. In my mind, a 4-switch buck-boost is simply connecting a buck and boost together, ...
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1answer
163 views

SMPS 5V without load, fluctuation on load TOP258PN [closed]

I am using PI Expert Online (this) to design a smps circuit for 5V, 2.5A output. I already have TOP258PN IC with me so built circuit for that. Change from schematics: I am not using choke and using ...
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31 views

TPS55165Q1 does not work in boost mode

I need a power supply that delivers 12v with an input between 8v and 35v. That's the reason I bought a couple of TPS55165Q1 from Texas instruments. I've made 3 different PCBs with a similar circuit. ...
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1answer
55 views

Where should I put my switch - on the enable of my SMPS or the power input?

I'm designing a simple board with a FitiPower FP6717 step-up converter chip (Datasheet) and a mechanical switch (SPDT) to enable or disable the output power. My design for the boost will be very close ...
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1answer
107 views

Is this an appropriate smps design? [closed]

I am an engineering fresh graduate with an interest in PCB design. I have been learning KiCAD which is really fun and I enjoy it alot. A friend came to me with the reference circuit attached here and ...
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1answer
86 views

Headphone Noise from Laptop SMPS

I have been facing an issue that has been a mystery to me for quite some time, and I wanted to see if someone here can potentially give me more insights on this so I can understand why it is happening....
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1answer
62 views

Would this switching power supply work?

I'm trying to design an integrated power supply to use in IoT projects that I'm working on, some including microcontrollers like the ESP8266 or ESP32. In previous projects I've made, power supply ...
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1answer
73 views

SMPS: Current Mode Instability (aka “sub-harmonic oscillation”) - Can we ignore it?

Currently I am designing a Constant Current charger for a capacitor which charges it from 0 to 350 VDC using a peak current mode controller. As we expected from simulation, I see there are sub-...
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1answer
52 views

Would a compact welder use MOSFETs or IGBTs

Want to know why some welders for a given output are much bigger than others. Already found one of the big reasons is needing to run on 120V instead of 220V How much space does a 220V AC input power ...
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102 views

Inrush Current problem?

I have a 360W 36V Switch Mode PSU which I am using in a garden lighting system I have designed. I'm in the UK so it's running off 240V therefore can supply about 10A. Each section of the ...
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2answers
101 views

How much space does a 220V AC input power supply save compared to a 120V one?

For a given output voltage & current, how much space is saved by using 220V instead of 120V input? Specifically, I want to know is it expected for 220V only welders to be much smaller than ...
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1answer
207 views

SMPS voltage drop in 230v ac to 5v dc flyback

I am building a SMPS circuit from a switching IC. This IC has feedback and enable pins for timing and current calculations respectively. Transformer Data: (10 pin 1-5, 6-10) primary: 1-3 - 60 turns, ...
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2answers
72 views

Conditioning input power supply on PCB

I have had issues in the past with using too close of an input power supply to the max rating of my main power regulator causing failures. For example, I used a 24VDC supply with a regulator with an ...
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1answer
47 views

Buck Converter - Closed Loop - Effect of decreasing inductance and increasing capacitance

Output voltage as a function of output current is plotted from oscilloscope data for a closed loop buck converter. Switching frequency is kept the same in both the cases. CASE 1 : Inductance = 2....
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50 views

Choosing power supply for device [duplicate]

This question is not Duplicate I am building a device which has a Raspberry Pi 3b +, custom Atmega328-PU or AU circuit (homemade Arduino), ws2812 SMD LED Arrays. Here, Raspberry Pi will provide ...
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47 views

Weird current in Push-Pull converter for high voltage multiplier

I have a push-pull converter driving a Villard-type voltage multiplier. The converter is built as naive as it could be: Two stacked MOSFETs with free wheeling diodes for the push-pull half opposing ...
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2answers
129 views

How find the optimal frequency of a high frequency transformer

I have disassembled a "Chinese" power inverter, I found a High-Frequency Transformer, with no label on it. I would like to make an inverter using this transformer to generate the High voltage to feed ...
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1answer
46 views

Regulate 0-6V output

I need to control output from 0-6V at max 1A (~0.8A). Looking at the datasheet for LM25010 it looks I could control R1 and R2 feedback resistors and achieve just that. Is it possible to get that ...
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4answers
69 views

Isolated Power Supplies for Inverter Gate Drivers

I am using a 3-Phase IPM IGBT Inverter Module in motor driver. This module has built-in gate drivers which require 4 Isolated power supplies for their operation. In all I have to design 5 Isolated ...
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2answers
59 views

How can I get this 12v motor to run smoothly, and is it set up safely?

This is my first attempt at electrical engineering, so I'm sorry if this question seems basic, I couldn't seem to find answers anywhere. I want to wire a 12v motor to an on/off switch and power with ...
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59 views

210v DC CV/CC supply

I have an old variable power supply that consists of a multi tapped transformer, a bridge rectifier and a choke. The transformer has two sets of taps on it, 6 coarse and 6 fine, giving 36 voltage ...
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0answers
77 views

Switching regulator not suppressing variance in input?

I am having a little problem with my switching regulator, based on a AP65211A and here is my schematic: Parts: ...
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2answers
126 views

Hold-up time in SMPS

I know the definition of Hold-up time in SMPS, and how to calculate the bulk capacitor. But I am wondering if someone can explain me how we define the hold-up time (sometimes 10ms, sometimes 16ms,...)?...
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2answers
133 views

Why does voltage change with load in buck/boost converters?

I recently learned about buck and boost converters. Both are switched-mode power supplies. Until recently, I had the impression that the duty cycle and input voltage determine the output voltage for ...
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2answers
35 views

Is the input voltage on power adapters RMS voltage or peak AC voltage?

For example, would a laptop power adaptor with a voltage input of 100-240V ~ be safe to use in a country with 230V RMS wall voltage? Thanks in advance!
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15 views

sawtooth generator for MCP1630

when using MCP1630V to design a buck converter in voltage mode control, is it preferabale to get sawtooth generator from the drive output pin or from the oscillator input pin? From the timing diagram ...
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1answer
98 views

Switching power supply toroidal heats more than 100ºC. Is it normal?

I’ve got this 48V 10.4A generic chinese switching power supply to power my mini lathe’s controller and stepper motors. The two steppers draw when working just 1.5A max each. And the controller 0.5A. ...
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2answers
96 views

Why the replacement of 7812 with R-78E12-0.5, DC/DC makes the circuit not working?

I have this simple surge protector and soft start inside the PSU. My transformer is out of its specifications yields 21.3V after bridge rectification. And 0.1A load (12V fan for cooling pass ...
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0answers
28 views

Limiting current in a NCP3020A switched DC/DC buck converter

I want to design a 12VDC to 5VDC converter using a NCP3020A. As my application has nothing special, I should follow the topology of the Typical Application circuit, and reapply the formulas in the ...