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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36 views

Weird output voltage from smps

I just completed a half bridge smps and had a test run. The series bulb on input just blink for a second at first and then shut down at it should. But the output voltage is quite weird because my ...
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A few questions about flyback dc-dc converters

I have a few questions regarding this flyback converter simulated in LTspice. 9V was stepped up to 27V using the transformer. My questions are: Why didn't the output voltage change with the change in ...
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How to compute VRM output limit

Three different B450 motherboards have an output stage supporting 40 amps (6 phase), 50 amps (4 phase), and 60 amps (6 phase). I would like to understand the relationship between input to VRM (assume +...
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100 views

How to power a 24V 2.5A DC motor with a switching power supply?

I need to power a windshield wiper motor at 24V. Switching mode power supply shuts off. The motor, rated 50 W, runs at 12V (50 RPM) or 24V (110 RPM). It's exactly the same one this guy has in this ...
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59 views

How to Design a Closed-loop Controlled Flyback Converter?

How to design a closed-loop flyback converter based on the figure and requirements given and find the specific values of paramenters? Find: transformer magnetizing inductance 𝐿𝑚, transformer step-...
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88 views

Eliminate beeps and bleeps in the power lines

The platform is having various supply voltages generated by the power supply: +5V (for digital part), +12V and -12V for analog part, including video amplifiers. My device, which is being installed ...
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66 views

Circuit of a PWM DC motor speed controller for a 12V 10A DC motor

I saw many circuits for this, most of them were using 555 IC, I wanna use a 12V 15A switching power supply for this motor, so I need a high current PWM speed controller but I don't know how to design ...
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82 views

LDO Switching regulator [closed]

I have a need for a switching voltage regulator which has following characteristics: Ultra Low quiescent current (pref below 2uA) Max output current 100mA or more Range on Input Voltage : 2.5 to 6 ...
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54 views

TL431 vs. SMPS transient response

I am currently working with few 150 W SMPS designs for industial applications with heavy transient load condition. Current design works well by mean of line/load regulation and device reliability but ...
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1answer
60 views

RHPZ in converter transfering the energy in a two steps approach -> mathematical model

Think of a converter transferring the energy in a two-step approach, like a boost or a buck-boost converter: first you store the energy in the inductor during the on-time then transfer it to the load ...
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35 views

Choosing voltage regulator for 3/4 AA battery powered pack

I've question similar to another SO question, with some minor differences, which I'll explain below: I'm designing a circuit which should work with 3 AND 4 AA batteries. Idea is to create two models, ...
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28 views

Designing a compensator - Control system - Missing value

I would like to determine the transfer function of the following circuit made of TL431. According to the different AN that I have read (and about this subject I really really thank Christophe BASSO, ...
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81 views

Bench top power supply design

I picked up an old computer power supply recently and I want to convert it into a bench top variable voltage supply, say 60 V/100 W. It's easy enough to boost the 5 V rail up to 60 V design what is ...
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39 views

Can a voltage peak detector circuit detect square wave overshoot voltage?

I'm building a simple inverter with an inductive-capacitive load. I wonder if I have overshoot voltage like this on my IGBT: I want to detect this overshoot, but since I don’t have an oscilloscope I'...
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47 views

SMPS powered DC motor inrush current problem

I stumbled upon a problem when connecting a DC motor to a SMPS. It's a 20W AC/DC converter with an 12V output that powers some 12V DC motors the processor and some LEDs. I needed to speed up the most ...
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63 views

voltage spiking due to strong gate driver

If I make the PWM signal to gate very steep ( with rising time tr is very small like 200ps) then at rising time the gate ...
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26 views

PSU charging / USB charging with data transmission - LiPo cell

I am designing Rev.2 of my Geiger counter trying to squeeze in more functionality in it and make it portable. I decided to go with single LiPo cell 3.7V, STM32 microcontroller and step-up converter 5V ...
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35 views

Unexpected voltage drop in the output

I've created a power converter based on an LM5085 IC. The converter was designed so that it can work with 24V in the input. Here is my schematic. Requirements: VIN - 24V Vout - 3.3V Imax = 1A Imin = ...
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37 views

Multiple transformer windings vs a single winding with a buck converter for dual output power supply?

I have to create a power supply that has both a 5V output at 1A and a 3.3V output at 0.4A. I was wondering if I should add another winding to my transformer or just make a 5V 1.5A power supply, and ...
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33 views

Switch mode power supply making for beginner

Hi I'm a beginner at designing smps circuits tbh its my first time and i don't wanna get into the headache of using pwms and octocouplers insteas i want a mosfet or ic that can regulate itself i.e ...
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56 views

Output transistors on the TL494 [closed]

I am building a SMPS with a TL494 and got stuck on the output transistors to drive the gate drive transformer. I have tried circuits with common emitter and common collector but somehow it doesn't ...
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1answer
52 views

How to calculate the needed capacitance of a start capacitor for a 12V 10A DC motor?

I want to use a 12V 15A switching power supply for a 12V 10A DC motor which has about 9A start current and 6A no load current, I also want to add a push button switch for on and off function to use it ...
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32 views

Zero Volt-Seconds Assumption in SMPS

What is the logic behind using the “zero volt-seconds” assumption for the analysis of converters and What are the limitations of analysis based on this assumption?
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89 views

Filter cap between positive rails in multi-rail power supply

Say I have this very simple power supply: Variant 1 A = +12V B = GND C = -12V Disregard any problems with additional filtering, regulation, and the fact that the transformer's primary isn't connected....
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52 views

Power Supply AC/DC Power OK Signal Control

I will combine 4 ac/dc converter (1000 W) by using parallel operation mode to create 4 kW unit. I will add 4 LEDs to observe converter signal health. There are digital output including POWER ON ...
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39 views

Whether a half bridge SMPS based on MOSFET or another one based on BJT will generate more switching noise at the output?

Whether a half bridge SMPS based on MOSFET or another one based on BJT will generate more switching noise at the output?, if other parameters such as output voltage, current, type of transformer core, ...
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37 views

Determining error in output voltages of a flyback converter

I'm currently designing a flyback converter and I just want to know how the error tolerances are calculated for a multi output flyback converter. I calculated the required primary number of turns: ...
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66 views

What the Schuko?

I purchased a welder for use in the US. It came with a Schuko cord end. A bit confused on rewire and cannot find any schematics or pictures describing how this circuit travels exactly. I'm very visual ...
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2answers
70 views

Modifying SMPS power supply to produce a negative voltage

In SMPS power supply that uses a single transistor to generate the switching signal ( no control IC), which component must be modified so the output voltage could be negative? I tried to reverse the ...
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43 views

AC adapter not working on one outlet only

I have a switching AC adapter with an LED on it that shows when it's plugged in and receiving power. It works fine in all my outlets except one. But this one outlet works because it powers everything ...
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2answers
52 views

Do I need to worry about EMI/RFI/etc. for 110V and 12/5V electronics in the same electric panel?

I am building an electric panel (steel) which will house automation equipment in my home. The box is 20x20x10 inches and will include the following (all attached via DIN rail): 12v and 5v switched ...
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62 views

Switching power supply (SMPS) for servo motors

I would like to find a switching power supply to power one ClearPath servo motor. I am aware that SMPS is not recommended for servos, but I don't need power for fast deceleration/acceleration. Beyond ...
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1answer
142 views

Hacking Dell charger to run directly from an external 19.5V power source [closed]

I needed to power my Dell laptop without having 220V (because my inverter is burnt in the middle of nowhere) in my van. By using a boost converter that can deliver the required power, I simply set the ...
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2answers
88 views

How can I make my flyback converter discharge immediately?

I'm using a flyback converter (220-100V to 19vdc) to power an electronics unit. But it doesn't discharge fast enough, this causes some relays to stay energised for a second or two after power supply ...
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80 views

SMPS Zener diode replacement

I have switch mode power supply (SMPS) rated for 32V 50 watt. I plugged it in main AC, checked its output then unplugged it. Then to put the SMPS back into its casing, to be on safe side I (tried too) ...
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86 views

Why did my Arduino Uno give me a shock?

My Arduino Uno R3 gives me an electric shock upon touching one of its pins when my legs are on the ground. The shock is not that trivial since if the pin is related to some LED the LED lights up which ...
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Need spec sheet on Cherokee International smps SP671-Y01A

I am trying to fix a power supply SP671-Y01A made by Cherokee International. It is a 24volt supply. If anybody has a spec sheet and or tell me the output enable pins that would be awesome. There is ...
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91 views

I want to increase the speed of my 12v DC trolling motor

This has been a project I have wanted to do for some time now. I live on a large lake where gas engines are not allowed. I love to fish, but some of the best spots are a long boat ride from home ...
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261 views

Cleaning power rail from switch mode power supply

In my circuit, I do not have control over what the power supply is used. Thus, I am preparing for the worst where a cheap noisy SMPS is used. I have some ADCs down the line that get their power from ...
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114 views

Help finding PWM IC with marking on device 'FA=606'. Package of device is SOT23 - 6

I found this 6 pin PWM IC in one of the SMPS. I am unable to find any of its details on Google. I am requesting if anyone could help me finding the device name. The marking is something like FA=606 or ...
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30 views

What is time constant for this UC3845 circuit?

Time constant tau=R*C=100 (us) Am I right?? How to get relation equation about V_ref and V_c? me: Am I right?
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41 views

Calculate dead time in synchronous buck converter

How much dead time is required for the switches in synchronous buck converter at a switching frequency let's say 1 kHz. Is there any thumb rule for choosing dead time with respect to the switching ...
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1answer
56 views

Building a buck converter using CMOS 555 with mosfet driver

Can I use ICM7555 IC to generate 300 KHz PWM signal and feed that PWM to IRL2104 mosfet driver to build a non-isolated DC to DC buck converter? I'm asking this question because I couldn't find any ...
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1answer
44 views

Oscillation of the Drain-Source voltage in flyback converter

The image below describes a flyback converter with a clamping circuit off and the leakage inductor is reset, so the clamping diode is off (blocking): My question is about the resonant frequency. The ...
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110 views

Stability of input filter in SMPS - Theoretical explanation

I read the Application note Wurth Electronics ANP008c about negative resistance of a SMPS input and how to avoid oscillation when using an input LC filter. I'm asking for a theorethical clarification ...
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49 views

Coupled inductors in flyback

I want to understand the following statement that describes a flyback converter when the switch is turned off : " When the PWM controller instructs the power switch to turn off, the voltage ...
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1answer
55 views

Connecting buck converter to 10mF 40v filter capacitor

I have a very well made custom-made lab supply given to me by a friend. It is capable of 1.6A max and 32V DC voltage. I want to ...
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103 views

Limiting battery input current to avoid voltage drop when activating LoRa radio

I have a battery-powered wireless sensor system that sends sensor information periodically. One requirement is that it has to be functional at very low temperatures. Powering this system is a Tadiran ...
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29 views

Parallel power bus management

The situation is: I have two sources of power. A battery rated for 6v-60v and a USB-C connector able to deliver up to 20v. What I need: Manage the power so that the battery is the main source and the ...
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