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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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83 views

explain the working of this circuit

I'm basically trying to understand how this Dc to Dc step-up converter work. please help me.[![dc-dc step-up voltage converter 1v-9v][2]][2] I need to design a DC DC step up converter using bjts. ...
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2answers
62 views

What's a safe method for determining the switching frequency of a blackbox ACDC converter?

My project uses an off-the-shelf ACDC converter that conceals design details from such as switching frequency (or SF range). It's 24 V output rated to 5 Amps. I want to measure it's switching ...
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0answers
37 views

How common mode choke helps in conducted immunity for power supply lines? (Automotive - 12V system)

Please find related circuit attached here: I have seen people using common mode choke on supply lines (between 12V (BAT+) & GND (BAT-)) for reducing conducted emissions by system over vehicle ...
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1answer
42 views

Dysfunctional IRF9540

simulate this circuit – Schematic created using CircuitLab I am trying to build my own SMPS and I was intending on using a P-Channel MOSFET for high side driving the main circuit. The MOSFET in ...
3
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2answers
54 views

What capacitors are proper to use for input of AC DC converter?

I am trying to build an 120 AC to 15 DC @ 200 mA converter using a Power Integrations LNK3206P. Using the full bridge rectifier setup on Table 10 from application note AN-70, Cin1 and Cin2 should each ...
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2answers
76 views

Fixing conmutation for high voltage switching with power MOSFET

I have an issue with a charge circuit for a capacitor as load. I want to switch approximately 400 V DC to charge a 1000 µF 600 V capacitor. I'm using a power MOSFET for this application. I need it to ...
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4answers
78 views

How to Turn off a PIC Microcontroller in high capacitance circuit?

Below image is the input voltage VDD to PIC16F18326. I am turning off (Switching off the mains supply) my circuit at point A (see image). Due to large capacitance at load, which is required in my ...
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1answer
59 views

What is the operating frequency of this IC?

It is the LT3751 High Voltage Capacitor Charge Controller, datasheet. I am trying to calculate the required value for the input capacitor for my application, but the datasheet does not clearly ...
2
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0answers
121 views

Large negative current spike in N-Channel MOSFET source when turn-off

I am working on repairing a power supply board of a LCD TV (200W power), more specifically, the PFC section (active power factor correction). See schematic (adapted from here): I've replaced some ...
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0answers
44 views

Can anyone identify this diode? S69D

I’m attempting to repair a totally dead Panasonic SC-HC30DB and have found a faulty diode in the secondary part of the SMPS. However, I can’t identify this diode marked S69D as you can see from the ...
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34 views

SMPS: Current Mode Control [Sub-Harmonic oscillation] - How to determine ramp when capacitor is unknown?

Currently I am working to charge an DC-link capacitor to prevend inrush currents. I want to charge the capacitor from 0 to 700V using with an Vin of 700V. I want to do this by using an SMPS and found ...
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1answer
42 views

Reactive vs Real Power in DC-DC Converters

I don't understand which form of power, reactive or real, should be dominant in a maximally efficient DC-DC boost converter. As the circuit charges the inductor, the current and voltage will be out ...
1
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1answer
91 views

5V Switching Regulator Problems

I have a circuit with two supplies. A 19v supply for stepper motors, and a 5v supply for driving the ATMEGA644, 3 stepper motor driver daughter boards, a bluetooth LE daughter board, and 2 ws2812b rgb ...
3
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2answers
290 views

LM22678 Unstable output

I am building a voltage regulator with the LM22678-5. I used TI WE-Bench designer to get the component values needed for the regulator: The regulator outputs 5V when there is no load however it ...
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0answers
26 views

Flyback, primary inductance selection for wide output current changes

I would build my first flyback converter. Converter would be designed for 2A max and load device would draw about 100-200mA for most of the time with 1.8A peaks. Peaks would take a little longer so I ...
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1answer
41 views

What does the ripple frequency of a buck converter indicate and how does it affect the DC device connected to its output?

What is the desired ripple frequency for buck converters connected to computers, networking device as power supplies? Can we judge the quality of power supply from ripple frequency? (buck converter ...
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0answers
48 views

Cant recognise a Damaged component of switched-mode power supply

I was repairing an smps ATX power supply I found a damaged component that I could not it recognise. I thought it's a power switch since it was mounted to a heat sink along with tow D13007 NPN power ...
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100 views

Can someone tell me what this 4-pin IC could be?

Actually searching for its reference (B0929) on the internet gives me nothing. Can someone please tell what this could be?
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5answers
136 views

Spec says 7-24V, can I use 25V?

I'm building an IoT device with a Wemos D1 Mini. It should control a relay, and also measure the temperature. The thing is, my only practical power source comes from my garage door opener which I ...
2
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1answer
85 views

What could cause my boost converter to output below its nominal voltage?

I'm very new to electronics and I'm building things and experimenting as a learning opportunity. I've put together a boost converter circuit and it works OK, but I've noticed that under larger loads ...
0
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1answer
32 views

SMPS Transformer - Different Current Densities for Primary and Secondary

I've seen a design sheet of an isolated off-line 5V/2A flyback converter. In the "Calculating Wire Sizes" step the designer uses 4A/mm2 for primary and 10A/mm2 for secondary. This seems quite ...
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0answers
180 views

Make a constant current source using a 700VDC supply at 4A

Goal: Charging a capacitor to 700V I want to charge a capacitor(any value) to 700V using an SMPS (buck converter.) to prevend inrush current. It's important that the system could charge the ...
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1answer
60 views

Boost converter drawing too much current

I am trying to play around with some SMPS boost converters, in order to power my Nixie tubes at around 170V (boosting from 20V to 170V). Yes, I know that there are already existing power supplies that ...
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0answers
28 views

Slope of the Inductor current

this forum is very helpful in the term of power-electronics. I got a question about LT-spice simulation. I want to compare the slope of the inductor current in two circuits.The only difference between ...
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1answer
55 views

Cordless dremel hard wire [closed]

4.8 v cordless dremel. I've got a bunch of different supplies laying around all different volts none exactly right what would be most comparable battery = 4.8v-.7Ah. Supplies I have close maybe ...
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3answers
66 views

Inductance value of an Isolation Transformer

There is a small isolation transformer 'L1' of 1:1 ratio as shown in the image. A 0-24V, 75kHz square wave is applied from push-pull mosfets stage at the 'V_SW' input of the circuit. I want to find ...
2
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3answers
162 views

32.768kHz crystal making audible noise

I am doing a project to record and log the voltages of an 8 cell lithium battery. The project is based on an STM32 microcontroller, and logging is done on an SD card. I have made the first version of ...
0
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0answers
35 views

High side N-channel Mosfet Switching output port short circuit protection

I have designed High side plus low side isolated combined N-channel switching using mosfets for high power switching through Mosfet. The power handling of the design is 24v/70Amp. The design is ...
0
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1answer
52 views

Decoding circuit with transformer topology

I am studying a circuit used for mobile adaptor, where AC to DC conversion is done through bridge rectifier ABS210. Transformer is used for isolation along with IC LP3783 (Offline PSR Driver) and ...
4
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1answer
350 views

Feedback in LM2574

I wonder what is the purpose of 'R66' at the feedback terminal of LM2574? I have seen its datasheet but I cannot find info about this. Instead of a single resistor there is a voltage divider shown in ...
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0answers
24 views

Which power source/elements are better for a spot welder?

I'm going to build a spot welder for the batteries of my RC models, but started thinking which power source is the better choise: 12V car battery with higher start current (500A+) Transformer which ...
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2answers
1k views

What's the goal of diode and resistor in parallel on SMPS?

While reading schematics diagrams from several switch mode power supplies of LCD TVs, I noticed that the pin which delivers the PWM pulse to the gate of a MOSFET has a diode and resistor in parallel. ...
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0answers
22 views

Which power converter topology has higher benefit of EMI/EMC?

Which power converter topology can be best suited for EMC compliance for small power converter to be used in LED lighting products. In my context I'm using a 5W non-isolated AC-DC converter which is ...
0
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1answer
67 views

Why does duty cycle seem relevant when calculating inductor current in boost converter circuit?

I've been working hard to understand boost converters and the role of inductors in the boost converter circuit. I found a pretty good list of basic calculations from Texas Instruments and I started ...
0
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1answer
70 views

How do inductor specifications impact their effectiveness in a boost converter circuit?

I've been trying to understand how to select an adequate inductor for a boost converter circuit. I'm a hobbyist so I'm not always sure what to look for, so I haven't been able to find something that ...
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2answers
40 views

Recommendations for 24V to 5V AC/DC converter [closed]

I'm working on an ESP8266 thermostat that should be powered by the 24V AC from the furnace. I'm looking for a converter to 5V DC that would be small enough to fit in a smaller enclosure and not ...
0
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1answer
58 views

different types of smps [closed]

I need a 12v 5A power supply for a heating element. I found out there are two main types of smps: first one is mounted in a metallic case and usually cooled by fan (in some websites it is called "...
0
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0answers
62 views

sg3525/ir2110 feedback problem

i use this schematic to build a half bridge power supply. but i have some problems and need some helps. the first problem is feedback.i think this feedback is not good beacause with this feedback ...
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1answer
54 views

Linear power supply vs SMPS (losses in transformer)

We know that, in a power supply, there are always losses taking place. If we have a linear power supply, the major source of loss is the core loss in the transformer. But in an SMPS, where we have a ...
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3answers
75 views

Is ripple of LC filter constant?

How LC filter ripple becomes independent of load. Does it remain constant or it varies with the load? I know that capacitor filter has low ripple in low load, and with high load its ripple increases ...
0
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0answers
19 views

Do I consider a downstream devices input capacitance when choosing the output capacitor for a switching regulator?

I am designing a circuit in which I chain together a few switching regulators. Each regulator defines specifications for capacitors to be placed on the input and the output. Do I need to consider ...
1
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1answer
59 views

Questions about a design for an SMPS post regulator filter circuit?

For minimizing SMPS ripple and especially noise, I’m trying to make a small interface which is a post regulator cascaded after an LC filter. I have come across some papers related to this topic and ...
2
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0answers
44 views

Can I generate following voltage waveform with single PWM FET?

I am designing power supply which must output following voltages at a maximum of 1.5 A stepped down from a 24 V DC supply. 24 V 13-15 V 0-5 V Waveform for one of the inputs requires following ...
0
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1answer
45 views

How does a non-isolated SMPS work?

My understanding is as follows: For an isolated SMPS, we first rectify the input ac voltage, then convert it to a square pulse using a switching regulator. It is then stepped down using a transformer,...
0
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1answer
48 views

How can I isolate the output of a SMPS

What options do I have for isolating the input and output of a switch-mode power supply? I think one method could be to use a transformer. I have read that many SMPS designs use a high-frequency ...
0
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1answer
57 views

Two PWM signals from TL494

I need to generate two open-loop PWM signals with different duty cycles for my converter. The frequency is 20kHz. I did generate one signal. Should I use another TL494 and connect it to the same ...
0
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1answer
53 views

SMPS Error Amplifier Behavior

In case of switch mode power supplies, we uselly use "Error Amplifiers" (Type 1,2 & 3), my question is: The output voltage of this amplifier (Verr), is it the DC error of the Vref and Vout (i.e: ...
0
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1answer
42 views

selection of power supply ( Linear power supply vs SMPS)

we know that, depending on the specification of our system, we design our power supply, which may be either a Linear Power Supply, or an SMPS. But, if there are no constraints of size, efficiency, ...
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1answer
40 views

smps block diagram and working for isolated topology

I have seen in most of the block diagrams of SMPS of isolated topologies, that the input AC voltage is first rectified and filtered to DC voltage. Then, it is passed through a high frequency switch to ...
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2answers
73 views

Do Battery Powered devices require bulk cap at power input?

I am in the process of designing a +5V power supply for a hand-held 2xAAA powered device. When using TI's webench simulator tool to simulate a switcher power supply that I am considering, I noticed ...