All Questions
Tagged with switch-mode-power-supply flyback
171 questions
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Flyback transformer design
My question is almost similar to the question Google.
The flyback transformer is actually a coupled inductor. So it must be designed like an inductor.
After obtaining the required inductance, it is ...
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0
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27
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LT8316 Multi-Output drop on 1 output under small load
I designed a Multi-Winding/Multi-Output Flyback to generate +40V and -225V. In my application, the outputs need to work in a flip-flop load, where only one output handles a variable load of 0 to 50W ...
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2
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76
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Is this flyback topology?
In below circuit transformer output is rectified and going to load.
Many smps circuits doesn't even have that L1 inductor. Where can I get more material to read on this?
source:
https://electrobuff....
- 1,358
3
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165
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Flyback SMPS - Poor efficiency and hot core
I built a flyback SMPS intended to produce ~800 V (variable) from a 12 V input (basic schematic below). I'm using a TL5001 PWM controller with an inverting gate driver, to drive a SiC MOSFET (GeneSiC ...
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1
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59
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MOV and resistor selection of smps,flyback converter
I am designing a flyback converter. Input is 60-300 V AC. At the input I am giving a mov and there is a resistor. What is the use of that resistor (10 Ω 2 W)? Will it be acting as a fuse or is it to ...
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57
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Can I deduce the saturation current of a transformer from the rated wattage and maximum frequency?
I have an SMPS transformer EE10, but am not sure about the saturation current it has, I tried doing some internet research, all what I can get is this so far :
I am trying to deduce the saturation ...
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49
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What is the mistake in the Current ripple ratio equation?
I was trying to do some research and see some online tutorials to learn designing flyback converter, I have seen this part of that play list , I could deduce some formulas from the video but I had ...
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2
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Modeling current limited Error Amplifier Output of UCC28C51?
I am designing a current mode flyback, and am using the UCC28C51 IC from Texas Instruments. I don't intend on using the error amplifier built into the chip, I intend on having the optocoupler ...
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38
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In a flyback, why does the Vin supply hit overcurrent protection mode if the PWM controller bias is turned on before it? [closed]
I am working with a DC-DC flyback converter with 60-325V Vin and 60V Vout. I'm using UCC2813-0 by TI as the PWM controller in the primary side. While powering on the flyback, I have to supply Vin ...
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71
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Why do the number of valleys change when load is changed? [closed]
I am operating a flyback converter with 60V DC input and 6V DC output. The load connected across the output is 500mA. My mode of operation is DCM. If I have 4 valleys in the magnetizing ringing of Vds ...
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What would happen if I connect a AC input to a DC-DC flyback converter without any rectifier? [closed]
I have a DC-DC flyback which has a 47uF, 450V bypass capacitor at the input. What would happen if I connect a 220 V AC supply at the input instead of DC? Will the bypass capacitor blow off, or will I ...
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116
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Why solid state capacitors?
I've been looking through multiple cellphone chargers and I have noticed that they all use solid state capacitor for the output capacitor of the switching power supply (flyback converter).
Is there ...
2
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3
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236
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Will a housekeeping flyback require EMI filtering? [closed]
I'm interested in designing a hobby custom power supply in SPICE using a full bridge converter topology. I will have various components which will require biasing, so I was also thinking of using a ...
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2
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168
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Generating a biphasic pulse
I was trying to generate a biphasic pulse for TMS application. I was referring to this website.
The waveform is given below.My circuit implementation is described as follows.
I am making a flyback ...
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1
answer
168
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RCC SMPS Regulation
Could someone explain how the auxiliary winding controls the output voltage on the secondary winding?
For instance,
How do the zener diodes function?
How do you calculate the output voltage as a ...
- 832
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427
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Continuous and discontinuous mode flyback Confusion
I was looking at the construction of flyback transformers and found that there are two modes - continuous and discontinuous. I have related questions:
Is the circuit design for continuous mode and ...
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NCP12400 ROPP (overpower protection)
This picture is a typical application circuit in the datasheet of NCP12400 flyback controller IC. What does the ROPP in the red circle mean and how does it work?
Some people say it is used to filter ...
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1
answer
463
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Two switch flyback converter MOSFETs voltage stress
I am exploring and experimenting the two switch flyback converter. I have a doubt, in this two switch flyback converter configuration, two MOSFETs are connected in series with sandwiched primary coil ...
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925
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Flyback converter design using UC3843
I am designing a offline power supply which will 24 V as output with 2.5 A. I found UC3843 as better option. I used TI we bench tool to design my power supply. This is the schematic I got from it. The ...
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402
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Voltage ringing on secondary side of DCM flyback
I am trying to find out the 'inductor' responsible for secondary side voltage ringing observed when flyback MOSFET(SW) turns on using LT8300 simulation in LTspice.
Frequency of ringing observed is ...
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2
answers
437
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compensation for flyback regulator with 431 and optocoupler
I am testing a flyback converter with secondary side regulation, by means of a 431 in conjunction with an optocoupler with nominal CTR of 50-100%. A snippet of the regulator part is below.
I have used ...
- 23.4k
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172
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Asymmetrical Half-Bridge Flyback Converters Simulation issue
I am using SIMPLIS to construct an Asymmetrical Half-Bridge Flyback Converter. Additionally, I am attempting to implement Synchronous Rectification on the secondary side. Please refer to the schematic ...
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Why two EMI Y-capacitors in series between primary and secondary?
Y-capacitors between primary and secondary are often used to reduce common mode noise in flyback SMPS, as explained also here.
I have read that two Y-capacitors in series are needed to be compliant ...
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228
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Instant flux density calculation of flyback transformer with airgap
How to calculate the instant flux density of a flyback transformer with airgap? I am trying to understand airgap is enough or not? Does the instant flux density reach saturation value or not? Also, ...
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3
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Why is the air gap important in a flyback transformer?
Why is the air gap important in a flyback transformer?
How should we consider the equivalent circuit of a standard flyback transformer?
If we are going to wrap all the windings of transformer to the ...
- 82
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53
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Flyback Synchronous rectification voltage-second balance control
Below figure is a flyback with Synchronous rectification.
there is a control method call voltage-second balance to use to control the Q2 switch.
I see this picture from internet, but I can't find it ...
- 585
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2
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338
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What is the most used bi-polar output SMPS topology in gate driver isolation?
I have some questions concerning this schematic:
What is the topology used here? I am guessing flyback without feedback circuitry.
Why is the TPS40211 utilized here? Is it to provide more current? ...
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1
answer
297
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Pulse transformer for two switch flyback converter
I would like to design a pulse transformer for a two-switch flyback converter, with a 1:1:1 turn ratio (1 input 2 outputs).
I have troubles choosing the correct Volt-second and inductance.
My MOSFETs ...
- 505
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2
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297
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Can you change the polarity of a flyback transformer by swapping the output pins?
I am using the following flyback transformer from Pulse electronics:
I am typically used to seeing the dots reversed on the diagram. For this transformer, would current be flowing out of pins 5, 9 ...
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2
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706
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Why doesn't SMPS controller VCC capacitor get fully charged to 310 V?
Most SMPS circuits have a startup circuit like the one in the schematic below:
The rectified 310 V goes through Rstartup1 and Rstartup2 to fill Cvcc to UVLO limit and the controller IC starts working....
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2
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1
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634
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What's Blanking time in Flyback
I read some documents (see below) about the blanking time of flyback. Both are talking about it, but I don't know exactly what this function does. I also tried to get an explanation from the datasheet,...
- 585
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3
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754
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Determining \$Z_N \$ and \$Z_D \$ for a flyback converter
According to page 448 of "Fundamentals of Power Electronics" (pdf) the small signal model of a flyback converter is
In my case \$R_\text{on} = 0 \: \Omega\$ so it should be ignored. Now, to ...
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What is the frequency at the input of the bulk capacitor in a flyback?
I am under the impression that the output frequency of the bulk capacitor will be the same as the switching frequency of the PWM chip. The input however I am a bit confused about, because if it is ...
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2
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246
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Two different topologies for flyback
I heard someone say the QR (quasi-resonant) flyback has a smaller primary side current than an ACF (active-clamp flyback) under the same circumstances. Is this correct?
I tried to search for ...
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DK1203 Flyback SMPS - How does it work?
Has anyone come across a DK1203 SMPS like this? I've come across ICs like the FSGN300N that have a startup pin and aux coil to supply the IC. How would the self-supply circuit in the DK1203 work? In ...
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ACF flyback clamp current issue
I study a paper.
There is a paper named "Design Consideration of MHz Active Clamp Flyback Converter with GaN Devices for Low Power Adapter Application"
I have a question about why changing ...
- 367
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2
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506
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Active clamp flyback clamp voltage calculation
Does anyone know how to calculate the clamp voltage? I read some papers and documents. Some of them use \$n \times Vo\$ to calculate the voltage, but when I use simulation to verify it I find the ...
- 367
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ACF flyback leakage inductor current problem
I try to use Basso's Free SIMPLIS document to run the active clamp flyback, and I try to use math to build the leakage indcuctor current waveform, but I got some problems.
please see the below ...
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338
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Active clamp flyback control questions
Can I use an SR flip to control an active clamp flyback control?
I am not very sure which method is a good choice to control the Qaux and Q1.
Could you please provide some suggestions?
- 367
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310
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Over-power protection circuit
About NCP1342, there is a protection circuit which was called Overpower Protection (on page 14).
I am confused about why this is over-power protection. There is no circuit to do the multiplication, I ...
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0
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120
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Leakage Inductance Delays the Secondary Current
I read Basso's seminar, on Page 30, it is talking about Leakage Inductance Delays the Secondary Current. From the formula, we can get the Δt, but I am curious about one thing if we don't add the RCD ...
- 367
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1k
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Flyback Converter Valley Switching and QR mode
I watched TI's basic flyback video about the different control methods.
and I am confused about some things, please see mine below questions.
1.) Valley Switching and QR, last time I ask a question ...
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2
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Why can't flyback work when the duty cycle is greater than 0.5?
I read this document talking about flyback design, and I am curious about why, when the duty cycle is greater than 0.5, do we need to adjust the VOR to make sure the duty cycle is less than 0.5?
What'...
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2
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438
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Flyback Frequency Foldback Mode (FFM) and Skip Mode
I would like to know why flyback needs to use Frequency Foldback Mode (FFM) and Skip Mode.
I did some research but I don't understand the details of what I've read. Below is a figure that I found in ...
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1
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130
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ZCD SIMPLIS function block questions
I find the figure which used to do the ZCD circuit.
please see the below figure. Does anyone know what's name of U7? I can't find this module in SIMPLIS.
I would like to use this way to do the ZCD, ...
- 367
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211
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Issues Choosing Flyback Transformer Specs & General Direction Help
I'm working on trying to figure out how to wind transformers myself and picking values etc. I currently have PQ26/25 Bobbins with PC95PQ26/25Z-12 ferrite cores (N95).
I have some smaller E cores ...
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98
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Salvaged magnetic materials for low performance 1MHz boost converter
I am wondering if I could modify a MT3608 boost module by winding a custom inductor / transformer for it, to generate a kV range voltage (at sub mA current).
I'm thinking of replacing the 22uH ...
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3
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Why does a flyback converter in DCM mode have a different oscillation waveform at start and end of MOSFET turn off?
As seen from the waveform, when the MOSFET turns off, it has some high-frequency oscillations (shown in red) whereas before MOSFET turns on it has low-frequency oscillations. I have found that the ...
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1
answer
484
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Flyback Cross-Regulation
The document "Under the Hood of Flyback SMPS Designs", talks about the cross-regulation (on page 8). I have some questions about that.
1.) In what condition the primary voltage will ...
- 585
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2
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442
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Flyback leakage inductance effect
The document "Under the Hood of Flyback SMPS Designs", talks about the leakage inductance effect (on page 6). I have some questions about that.
The below questions are from fig 5.
Why high ...
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