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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29 views

Input Capacitance in LM 2596 Step Down voltage regulator

What is the significance of the input capacitance (680 uF) (uF = microFarad) at the input of the LM 2596 ? LM 2596 is step down voltage regulator. Please refer: http://www.ti.com/lit/ds/symlink/...
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39 views

How can I calculate the sparks when I discharging a big capacitor?

Several years ago I've tried to find answer to this question but I couldn't find the answers. I hope you help me. Because my job I have to discharging constantly "big" capacitors ( 400 vdc, 300 ...
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59 views

Is it possible to use a Zener diode as a High Pass Voltage

I'm trying to ensure a minimal Vin to solar powered (incl. battery ) ESP8266 project. When battery voltage drops under a certain value , MCU enters an undefined state, which prevents it from wakening ...
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Why is there such a large difference in efficiency in these two boost converter configurations?

Here is the datasheet I realize that the converter has to "work harder" to boost a voltage from 2.8V-6V to 48V than it does from 8V-38V to 48V, but I'm curious why there's such a significant drop in ...
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30 views

Line Filter in Power Supply question

I have faulty power supply in my digital reverb unit and after replacing all capacitors the problem is still there - fast on/off switching with clicking sound. It does turn on sometimes though but ...
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39 views

Error amp compensation on pwm controller

I'm trying to build a half bridge smps for 325 VDC to 30 VDC using SG3525 controller IC. I have no idea on how to use the error amp on this chip, especially the compensation pin. [ [ I have seen in ...
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49 views

Placing an RLC input filter at the input of a buck

Since bucks have current spikes at the input side, it's best to use an input filter as you get better noise reduction than using an output filter (afaik). Using a regulator IC however, that is, one ...
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40 views

Misunderstanding document about leakage inductance in a flyback converter V2

I m back again on this document ! :D The document teaches me a lot of things and I think it will help me to better understand the losses across the switching components. I really appreciate if someone ...
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Boost power losses - What is “Voltage drop of MOSFET”?

I'm following this tutorial on calculating boost converter efficiency and I'm a bit confused on the "Voltage drop of MOSFET" variable. Is this just the voltage drop of the FET when it's on? Meaning it ...
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57 views

Positive-negative voltage from dual supply

I'm trying to build a low cost hifi (Hiraga Le Monstre) but I have two old computer PSUs at hand so I tried to use it as power source. The Monstre needs +12V and -12V, computer PSUs have both, but the ...
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61 views

Current spikes when MOSFET turns on and voltage spikes when MOSFET turns off

I studying for my Power Electronics course and have come across something which I can't seem to wrap my head around. In a lab, we built a buck converter with an inductive load and measured various ...
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47 views

Misunderstanding document about leakage inductance in a flyback converter

I am currently reading a document about leakage inductance in a flyback converter from ON SEMICONDUCTOR . Here it is : https://pdfs.semanticscholar.org/c061/313303ee8c231b069be4f0d67d9e4cddcbf0.pdf (...
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41 views

Center-tapped transformer and inductance calculation for transformer driver

Using a push-pull transformer driver, for example the LT3439 like below with a center-tapped transformer, more precisely this one here So we there is a center tapped transformer (with 1:1.3 ratio ...
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2answers
60 views

Improving Flyback DCM Peak Power using CCM

How does CCM can improve the peak power of normal DCM flyback power supply? I noticed that some of flyback converter can operate in both DCM & CCM. During this peak power excursion, the converter ...
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42 views

What is the parameter of the power source that satisfies the inrush current of the load?

Power supplies (more specifically, the SMPS') have voltage and current rating on its label. However, the inrush current supplement capability will depend from supply to supply. What is the unit of ...
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SMPS coupled inductor selection

I am in the process of designing a switched mode power supply as I need rather high power(12V 2A). I took a look at the TI tool that throws a basic circuit at you. I understand the danger of such a ...
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59 views

Leakage inductance is function of the air gap

I would like to know why leakage inductance is function of the air gap transformer. How does it influence the leakage flux ? What is the relation between them ? Thank you very much :)
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43 views

SMPS Input/Output ripple current and ripple voltage

I found a presentation regarding SMPS and found this slide. I am not totally able to grasp the concept of the input and output ripple current. In the above image I have the following questions : I ...
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2answers
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Is building a DC-DC PSU PWM controller from discrete components a terrible idea?

I am building a 1kW PSU that is controlled with DSP MCU. It requires a lot of features such as synchronous rectification, bidirectionality, current regulation. Those features make the PSU very exotic ...
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Eon and Eoff IGBT losses

I have read several documentations about switching losses in IGBT. Most of documents indicates to use Eon and Eoff curves to calcul the switching losses through the IGBT. Nevertheless, the Eon and ...
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1answer
59 views

Pi filter design for SMPS output ripple

Given a circuit like a buck-converter like the AOZ1284PI in a circuit such as this one: Or push-pull converters such as this one: If one was to design at the output a low-pass PI filter with a ...
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43 views

Suggestion on Power supply design

I am looking for Transformerless power supply design. I have MCU 5V. and would like to drive 12V/24V relay with single LED. i have 4 pots 10K/200k for timing So i prefer 230VAC to 12V/24Vdc output ...
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61 views

Why is an Enhancement P-Channel MOSFET Used?

I'm trying to design the power circuit for my project. I wanted to implement both USB and a LiPo battery to power it. I came across this circuit online but I'm struggling to understand how it works. ...
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How can I eliminate noise from a switched mode power supply through a laptop? [duplicate]

The laptop has a metal case, the charger is pulling 240v and outputting 19.5V When my hand is in contact with the metal case there is no noise coming through the headphones. If I draw my fingers ...
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28 views

Controlling low wattage SMPS with SSR

I have an AC to DC power supply (specifically the Mean Well RS-25-48 datasheet). When the power supply is not being used, I want it disconnected from the AC mains. I've thinking about using a SSR-...
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26 views

LM2576-X library for Proteus

I'm using proteus 8.9 SP0. Is there any library for LM2576-X (x = 3.3, 5, 9, 12, 15)? I have LM2576-ADJ (adjustable) but I need fixed voltage series.
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What is the RMS value of this waveform

I would like to know what is the RMS value of this waveform. I would like to see the mathematics. I ve done the mathematics but it seems that the result has a lot of terms ... If some approximations ...
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21 views

Switching Frequency for Flyback Quasi Resonant Converter

As I know, the major difference between normal flyback converter & flyback quasi resonant converter is for flyback quasi resonant converter, the switching frequency is variable. This means that ...
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24 views

Determining the worst case VCEsat

I would like to determine what is the worst case VCEsat at a certain collector current and a certain gate emmitter voltage of an IGBT. So I have to do a linear interpolation of the worst case output ...
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1answer
58 views

10kV high voltage switch using mosfet stack

I need to make a pulse generator for a 10kV power supply, few mA. Surprisingly, I could not find any standard design of HV switch using mosfet (Sic or not) stacks. Could someone give me some ...
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Whats the difference in these 2 input filter dampers?

Hi Im designing input filter for tps54202, with input 12V, output 3.3V at 0.5A. To pass emission test I need input filter, L+C should be good for that, but Ive read that its good to add damper to get ...
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67 views

Why do some SMPS power supplies require an input voltage select switch?

I have 2 SMPS power supplies near me. One is an ATX power supply, the other is for a 3d printer. They both are rated for 110-240v in, but the ATX supply can handle the full range automatically, while ...
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37 views

Evaluation of the primary inductance of a transformer whose core is saturated

I would like to know if it is possible to theoretically estimate reasonably the primary inductance of a transformer when its core is saturated. Otherwise, what is the best way to do it by measurement?...
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2 switch forward converter oscillation simulation

Here is the simulation of a 2 switches forward converter : The blue waveform is the voltage across the inductance. It seems that there is an RLC circuit. R is really low, which is why the ...
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42 views

Calculating A Transformer Core Power Capability

I'm trying to build a transformer for a full bridge dc-dc converter and it's my very first time to design a transformer and I got limited knowledge. I'm checking some ferrite cores and I've found ...
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1answer
99 views

Low cost buck SMPS with IC AOZ1284 - 5V x 4A - values for COMP pin

I want to use a buck converter based on IC AOZ1284PI from Alpha & Omega Semiconductor. AOZ1284PI is a low cost buck controller. For example, on Digikey it costs USD 0.51 @ 500 whereas the TPS54340 ...
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33 views

Improve protection of device that got damaged by a primary side short

Today I swapped one of our devices that got damaged by the customer during installation. The device consists of a base board with several modules (power supply, IO cards, processor board, display+USB, ...
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33 views

Fuse design for taking in account real-world very small transients

A bit of context I came up with this question after someone suggested that two fuses are better than a main one in the below configuration. The converters are SMPSs which regulate output voltage. ...
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56 views

Perfect component on LTspice

Is this possible to have perfect components in LTspice? No parasitic inductance, no parasitic capacitor, no resistor, etc? Is it not possible is it possible to make a model and model it with no ...
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24 views

Parasitic Source inductance and switching Mosfet

simulate this circuit – Schematic created using CircuitLab Consider the above circuit, (the values are not correct). When I want to turn off the MOSFET, the output of the driver would be 0. If ...
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34 views

Simulation of an asymetric half bridge not working

I m not able to simulate an asymetric half brige circuit :( I m new on LTspice... Here is the simulation which is really simple ... When I simulate it, I am surprised to not have 400V across the ...
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96 views

Can a multimeter really accurately measure the output current of a SMPS?

Most multimeters are bandwidth-limited to below 1khz while the current ripple of most SMPS is well above that. Even benchtop multimeters usually have bandwidth up to ~300kHz, which is not enough to ...
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63 views

DC/DC converter with 12 outputs, low noise?

I need to 5V to 5V. It might seem surprising but let me expain. I need to convert a voltage of 5V with 60mV ripple (coming from a PSU doing 120V AC to 5V DC) to say 5V with low ripple. I'm however ...
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83 views

High side MOSFET driver with transformer

I am reading the application note " Fundamentals of MOSFET and IGBT Gate Driver Circuits" written by Texas Instrument. In order to control High Side MOSFET, the application note suggests to use this ...
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Drawing 12V at 12.5A from an ATX power supply [closed]

I have an espresso machine for car use that runs on 12V, but I have been pondering the idea of getting an AC adapter so I could use in on 220V AC power as well. The machine draws a much as 150W (12.5A ...
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78 views

Designing an air gap transformer Misunderstanding

Suppose my core is actually with a design which make it saturated and the voltage on the secondary is too high. So I have to decrease the secondary voltage: For this I can increase the number of ...
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1answer
36 views

Good solution for TPS54202 input filter design?

I trying to make tps54202 switch regulator for esp32-wroom which would pass EMC test. https://www.ti.com/tool/TIDA-00948 By reading guidelines of designing they say that to pass EMC test you need to ...
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54 views

Wondering about the components in a chinese amplifier

I just bought an SMSL Audio SA98E. It is a switched power supply based on the TDA7498E. When I googled images of it I saw that they had different internals. Different components inside. Could this ...
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54 views

Is the TPS54202 buck converter a good solution to pass the FCC SDoC?

I want to design a PCB with the ESP32-WROOM module which has bluetooth. I want to pass the FCC verification. I would use a linear regulator, but it makes too much heat. My input is 14V car battery, ...
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1answer
60 views

What is the difference between pulse-skipping mode and burst-mode in power converters?

I have been looking at methods to regulate a resonant converter which switches from full load to zero load at rates anywhere from 100Hz to 100kHz. I am looking online at some journal/conference papers ...

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