Questions tagged [flyback]

A flyback diode is a diode used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply voltage is suddenly reduced or removed. A flyback transformer, also called a line output transformer, is a special type of electrical transformer designed to generate high voltage sawtooth signals at a relatively high frequency.

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Flyback primary side control

I read the LT3573's datasheet, I have some questions would like to ask. Based on this block diagram, 1.) What's the main function of the below circuit (red circle). 2.) If I need to detect the output ...
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50 views

Strange Isense shape for my flyback

I have strange shape when I'm measuring Rsense voltage, before that circuit, I have already made a flyback conerter with this SMPS transformer https://docs.rs-online.com/696a/0900766b80107114.pdf and ...
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86 views

What is the min and max input voltage range of a buck converter to maintain efficiency above 90%

I want to design a stepdown converter from 72V lithium ion battery to 12V, 5A. I am torn between using a flyback converter and a buck converter. Which topology will give me maximum efficiency at that ...
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84 views

Rogue winding on flyback transformer?

I was reverse engineering a battery charger (Lidl brand Parkside 20V battery charger PLGS 2012 A1, with smart functions, among them charge current and termination voltage settings) and came across ...
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53 views

Flyback transformer simulation in Lt Spice

I am trying to simulate a flyback transformer in Lt spice having an input voltage of Vin = 12 V, turns ratio = 8.45, coupling coefficient = 0.8. As per the calculation, output voltage should become ...
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44 views

Splitting output power of a PFC stage to three flyback converters

I want to design three flyback converters whose input is taken from a single power factor correction circuit based on boost converter topology. The PFC stage delivers 200 W (400 V, 0.5 A), and I want ...
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153 views

Understanding flyback power supply with weird snubber circuit, and general function?

Hello fellow wanderers of the electromagnetic plains, I'm looking to replicate the function of the below pictured reference design, just a simple 230VAC SMPS using an iW1700 chip (72kHz operation), ...
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96 views

Constant Voltage Applied to Inductor

I'm seeking clarity on understanding what happens when a constant voltage is applied to an inductor. I gave this explanation in another thread and it was regarded as wholly misguided in the following ...
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4answers
68 views

Capacitor between flyback diode and inductor

In my recent endevours in switching regulators I came to understand the need of a flyback diode in non-synchrounos regulators. From my experience with relays I know the flyback diode is placed in ...
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65 views

Magnetizing Inductor vs Transformer

I am a bit confused by the diagram - are there two inductors in parallel on the primary side of the flyback transformer? How does no current flow through v1 when the switch is closed?
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Flyback Converter: Where does the reflected voltage come from?

I have not been able to find a 100% clear answer to this question, but here is what I have found: From my understanding, the answer is it comes from the primary side inductor trying to resist the ...
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2answers
103 views

Inductor Back EMF Direction Relative to Changing Current

I have spent a lot of time thinking about Faraday's law and common explanation as given on wikipedia does not sit well with me. I may be confused. My concern is entirely with the wording of this ...
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4answers
111 views

Methods for high current DC motor emergency cutoff

I need to add a secondary means of cutting off power to a motor for safety reasons if a state change is detected on a 3.3V logic level signal while it is operating. The requirement I have is that it ...
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518 views

Snubber diodes on relay h-bridge

For my project I am controlling a motor 12 volt 6 amps (forward & reverse direction) with the help of two SPDT Relays that are controlled by a 2 channel remote as shown below. Where do I put the ...
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107 views

How to add a flyback diode to protect a relay on another PCB that does not have a flyback diode

I have a PCB (SEPARATE PCB) that I want to test by building up a "Test PCB". The test will involve switching the relays. This PCB (SEPARATE PCB) has a few relays on it, however, they do not ...
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248 views

Which flyback diode for magnetic buzzer

I am a novice, and I'm playing around with SMD magnetic buzzers. For instance, the CUI CMT-322-65-SMT-TR. In the datasheet they recommend something like this: After some Googling I learnt the diode ...
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1answer
45 views

Tesla coil with flyback transformer and ZVS circuit

I am new to the field of electronics and I might have some wrong concepts. I was thinking of designing an old fashioned 'spark gap' Tesla coil. Materials I have: a flyback transformer a cheap ZVS ...
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68 views

Current sense pin detect too quickly (Flyback)

Here is my circuit: simulate this circuit – Schematic created using CircuitLab There is two problems: Firstly, the sense circuit don't open the mosfet at 1V, yet the zener at the V+ in the amp ...
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Does a flyback diode have to be connected to the + lead of a solenoid, or can it go directly to the power supply?

I am designing a control box to switch 24V DC high speed solenoids at a max frequency of 200Hz. They will be controlled by an Arduino Mega through N channel, rfp30n06le MOSFETs. Here is a photo of the ...
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654 views

Braking a brushed DC motor with a flyback diode

I've seen many references to braking a brushed DC motor by shorting its terminals. As I understand it, the motor torque is relative to the current through it, which should dissipate relative to its ...
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1answer
68 views

Choosing the right diode for my H-bridge?

I'm making a H-bridge for a 12V DC-motor. I have to choose a flyback diode but I have a hard time determining the motor's back EMF voltage. I'm assuming this voltage won't be more than double the ...
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85 views

How to calculate auxilary capacitor for flyback

here is my circuit, simulate this circuit – Schematic created using CircuitLab The components try to restart but no results. Vcc output in yellow. I don't find in internet how to calculate ...
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39 views

How to calculate power requirement of Zener diode for specific frequency of operation?

I'm planing to control injector from MCU and this is schematics I came up with. Power supply voltage is 14V, inductance of L1 is 0.0014H, resistance of injector 16.6Ohm, and switching frequency is ...
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41 views

Rated drain to source voltage of a power MOSFET sustaining back EMF of solenoid

I have an H-bridge that is using 4 n-channel MOSFETs with max rating of 500 V 100 A drain to source driving a large inductor/actuator reliably. I'd like to find a cheaper MOSFET since the 100 A is ...
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113 views

Ultrafast rectifier diode: how can I calculate the maximum frequency?

I built ESC that had a 1N4007 as flyback diode. It was destroyed because my ESC was working with high PWM frequency. I replaced the 1N4007 with BYV29 ultrafast rectifier diode. The result was good ...
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1answer
94 views

What could cause this flyback output current oscillation?

I designed a dc-dc flyback converter that is expected to reach 30 W output power. But it seems there are problems with reaching maximum power. Firstly I tested without the input filter and with non-...
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52 views

Can any one explain what type of compensation is this

I will be using the UC3844 controller IC in combination with TL431 to achieve peak current mode control in a 150W forward converter. After some research, I found this schematic on the internet: There ...
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1answer
46 views

Flyback bode plot & type 2 comp

I'm trying to compensate a flyback boost circuit. Unfortunately I seem to be failing to make the gain of the system ever cross 0 dB. I feel like I'm missing something obvious... Like a pole? I'm ...
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3answers
197 views

RCD clamp and RC snubber design question

I have two questions about the RCD clamp and the RC snubber question in flyback. Below the figure is a CCM flyback converter with primary and secondary clamps and snubbers. Here are my questions: ...
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99 views

Why does Vref have this waveform?

According to the datasheet of the UC3843b We have in the Vref output 5V DC, however when in my flyback circuit Vref has this waveform: The secondary and auxiliary are not represented, My circuit: ...
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2answers
86 views

DC motor flyback diode get very hot (then roasted) [duplicate]

My motor works with 5V and consume about between 6 A and 8 A , controlled by ESC with PWM , and there is 1n4007 flyback diode to protect it , when i am working with PWM frequency = 350 Hz ( it works ...
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ESC (flyback diode)

i bulid ESC circuit based on TLP250 gate driver and IRF3205 MOSFET ,My motor works with 5V and consume about between 6 A and 8 A. the ESC circuit works well over month with software PWM frequency = ...
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2answers
297 views

How does a flyback work when there is no output load?

From what I understand, when the MOSFET is ON, the output diode (D1) is reverse biased. Then when the MOSFET turns off, the magnetic field of the transformer collapses and provides power through the ...
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Why does my flyback give me 1.5 output voltage

Here is my flyback circuit: simulate this circuit – Schematic created using CircuitLab The ZCD circuit isn't represent because I didn't find auxiliary SMPS in the list of components. Can ...
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1answer
61 views

MOSFET body diode and inductive load

I want to open a solenoid electromagnetic lock using an IRFR024NPbF MOSFET. Datasheet: https://datasheet.lcsc.com/lcsc/1809062114_Infineon-Technologies-IRFR024NTRPBF_C2583.pdf Generally speaking, I do ...
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114 views

Can a PFC work without feedback?

I want to test my PFC using MC33262. How can I be sure that it works? I see any signal on GD pin, yet I powered it correctly with 10-12 Vin the Vcc pin. Vac = 230 Vrms Does a PFC emit a frequency by ...
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28 views

How can we calculate Vcc voltage of power factor correction

I have this Flyback circuit: I'm trying to calculate what is the voltage in Vcc input pin of the PFC, however it seems to be hard for me. The PFC is an L6562, the datasheet gives us this internal ...
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1answer
73 views

Issues with POE isolated PSU - Flyback converter circuit getting hot - Maxim MAX1769 - POE

I have designed a POE device where I used the MAX17690 flyback converter to implement an isolated PSU for my device. I used the reference design MAXREFDES1105 (5V/2A design) from Maxim to size the ...
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Bench power supply with no minimum output voltage

Just like many other electronics hobbyists, I am trying to build a variable bench power supply with 0-30 V and 0-5 A output. I have gone through various sources to get a basic idea of how to design ...
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57 views

Can a low side L-spike destroy a turned off microcontroller through its ground pin?

I am working on a low power project involving servo motors and an STM32 Bluepill MCU board and I was wondering if it was necessary to place a free-wheeling diode as shown in the schematic below (D1). ...
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1answer
39 views

Using UVLO functionality on LT8315 Flyback Converter

UVLO=Under voltage Lock out I have a circuit made in LTspice which is straight from the datasheet of the LT8315 flyback converter. It takes an input voltage range of 20V-450V and outputs a constant ...
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2answers
155 views

Selection of MOSFET for flyback transformer switching circuit

I am working on a project that uses a transformer in flyback mode to create plasma arcing. It's based on a simple circuit that's available in a lot of DIY kits which uses a MOSFET to switch voltage on ...
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107 views

Zero current detect circuit

I would like to make a primary side regulation (PSR) flyback converter, but I have one thing I do not understand. I read this document from ON Semi. If I want to do PSR, I need to detect the diode ...
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112 views

How long does it take to charge a 1 uF capacitor with full rectified 5000V output from a flyback transformer? [closed]

If the voltage is 5000 V and the maximum available current is 20 milliamperes, and there's a 1uF capapacitor and 100 ohm resistance of the secondary. We can ignore the internal resistance of the ...
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1answer
94 views

Can One Flyback Diode be used for multiple relays controlled by the same switch?

I am working on a project where several 12V relays need to be controlled by the same push-button switch, essentially running the relays in parallel. I wondering whether relays configured in this way ...
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1answer
94 views

Sub-miniature signal relay (normally closed SPDT) getting stuck due to arcing

I have a 24V motor which is driven bi-directionally with PWM using DRV8873 H-Bridge motor controller. The circuit looks as follows: For normally driving the motor in either of the direction, I switch ...
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1answer
127 views

Flyback power supply instability issue

I have created a switching power supply: Input: 230 V AC Output: 12 V DC, 1 A Controller: UC3844 Topology: flyback Switching frequency: ~ 100 kHz Schematic: When I start this power supply, output ...
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2answers
83 views

FET protection when switching an inductive load with an inductive power supply

I am building a wind powered water heater. The system has a wind turbine that turns a brushless DC motor as a generator. The 3 phase output from the BLDC is rectified and passed to a heater load. A ...
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47 views

Flyback Transformer selection for Active Balancer on Automotive BMS project

I am designing an automotive prototype using an active balancer (LTC3300-1) where all the components must meet the AEC-Qxx standard. I managed to find all components compliant to AEC but its imposible ...
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65 views

Can I reduce flyback transformer into a single inductance to calculate the duty cycle of the MOSFET?

I am trying to calculate the duty cycle of the MOSFET in a flyback topology SMPS. From the selected converter's datasheet, I am given the equation: Since I am using a flyback topology, what is my L ...

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