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66 Threads found on edaboard.com: Isolated Flyback
I think I would take two bites at this particular problem. First I would build a non isolated boost converter to convert the incoming 9v to 36v up to something just slightly above 36v. Then I would build a full bridge that always runs at full maximum duty cycle through a transformer to generate the isolated 18 volts. As the primary voltage wi
Need help. Need to design a dc/dc isolated voltage regulator. Vin 60-160 v Vout 5V Io=0A - 5A Efficiency more than 83 %. The design should fit in 110x58x26 mm volume (aluminum box) I started (draft design on paper) with flyback DCM topology. 1) ICE3BR0665J controller, 65 kHz, 0.65Ohm RDSon 2) VS-48CTQ060PbF output Schotky diode
I am looking to design a Non-isolated DC-DC Converter with POWER Integration Tool. Input specs:90-270VAC Output:12v-500mA (Max) The design should be transformeless.. can include only inductors cos it is Non-isolated converter. I have gone thru Linkswitch in PI-Expert, But i am not getting the Non isolated design options. Kindly (...)
Hello, i have recently designed a 7V to 200V DC-DC SMPS converter, using LT3757. The output current is in the 1-10mA range. I use a DA2032 from coilcraft with a 1:10 ratio. At steady state, i get peak currents of 1.5A at the primary. My controller supports only non-isolated flyback, due to the nature of the resistive divider from the output. I a
I recently bought some of these ultra low cost Chinese power supplies, fully expecting them to be total rubbish. To my great surprise they work extremely well with excellent voltage regulation and and a very wide input voltage range that would work anywhere in the world. They are not a buck regulator, but a proper fully mains isolated dc power supp
Yes just use a flyback or two transistor forward to get the isolated 11.5V, 3.5A. Stick with a separate buck for your other output whatever that is? Alternatively use a single flyback with two isolated outputs to give you each output. I wasn't sure what your actual vin was?
Hi, Please check with your gnd of ic, the primary gnd and secondary gnd should be isolated! Bill Lee
You mean your fet on times are sometimes very long or short? Anyway, a good way is just to do a little flyback type high side isolated supply and reference it to the bridge node?in a full bridge do one for each side of the bridge. Don?t put a y cap between pri and sec as it will just conduct huge pulse currents. Put a third winding on the flybac
hi, i have just finished a 20 watt fly-back converter with wide input range 130 to 700 DC input by following application note. Is it possible to add a small micro controller at the output side (which is isolated) to adjust the output voltage by using up down buttons or by using commands
hello guys i want to use a mosfet as a high side switch ( instead of a relay) there is no fast switching (of duty cycle) just 0 or 1 , just ON/OFF each couple of seconds . to turn on the high side mosfet , you need about 12-15v between gate and source . but i am using a micro-controller or a key button (digital pin NO PWM), so i need a
I want to make a Push Pull type DC-DC converter with multiple outputs for driving the gates of an inverter and also some control circuits. While bootstrap method is popular, it has it's limitations. All the people at our college use a large no of isolated power supplies to do this and I want to make the Power supply part compact and cheap. I am th
Hello, We are doing a 60W isolated offline flyback (120W peak). We are using an ETD44 ferrite core with 1mm gap. The transformer winding company say that they cannot glue the ETD44 ferrite core halves together because it is not a robust method of adhesion. Is this true? They tell us that they must instead use the core clips to hold the core ha
The topology designated "buck-boost" in the RT7302 datasheet isn't but an non-isolated flyback. It saves some transformer copper but the primary waveforms are essentially the same as with regular isolated flyback. It reduces the "huge voltage stress on the power switch" only in so far that additional overvoltage caused by (...)
Hello, We wish to scope the voltage across the output diode in our offline , isolated flyback SMPS. (to see how high the ringing voltage goes) Should we use a differential probe, or will it be accurate enough to simply connect the actual scope probe directly?
Unregulated DC/DC converters (fixed voltage ratio) are usually made as forward converters. If your converter also implements voltage regulation, flyback can do this without additional energy storage inductors. The title is misleading because the problem hasn't to do with motor controller function. Rather "converter for isolated mcu supply".
Hello all. I am working on a microcontroller based flyback converter. Since the flyback converter is an isolated DC-DC Converter, it is using an opto-isolator as a feedback element. Attached with this post is an image from a Texas Instruments Application Report of a TL494 based multiple output flyback converter. (...)
Presumably you need an isolated output? A flyback will do it for you, we have designed a number of these types, easy at the power levels you require.
Hi I want to build an isolated power supply. Input will be 12v DC and output is 12V and 9V but isolated. How to do that? If smps is used, which switcher should be used?. I don't have any experience with SMPS and power supply, however want to build one as soon as possible. Can anybody please guide.
If transformer is fine, then there may be problem with the feedback circuit. I mean you can check by giving 3.3V from outside to your viper switch and check for 3.3V output if its coming correct and this will verify if everything including transformer and your switching of mosfet, is fine and then compare giving your actual
Hello, This product does not have the regulatory 8mm of isolation spacing from the mains side to the LED time 20:52 of the following, appears to be the proof that this mains light bulb not isolated.... Therefore, is it ok if i do a 15W flyback with bifilar wound enamelled copper
I am trying to make an isolated power supply.. The spec is as follows... Vin---Line voltage----90 to 265 volt RMS, 50Hz, Vout: 16V Iout: 15A, Converter: flyback, Switching freq: 100KHz, Please help me on transformer design, Snubber design, Mosfet selection PWM is controlled with the he
Witch ICS are most popular in commercial use SMPS? I need a DC/DC, 48V/48V (~30W) isolated power supply (flyback topology). - tantudaisu - For flyback topology, the UC384X series of controllers (UC3842, UC3843, UC3844, UC3845) is super popular. There are also other popular controllers such as MC34063. And then,
There are two isolated DC/DC flyback converter topologies: with optical coupler vs without one. Advantages and disadvantages of each of them? What about load regulation? Does topology without optical coupler suits for dynamic load applications? -tantudaisu-
Hello, I am doing a 45W, DCM flyback (isolated) with 90-265VAC mains input. (Vout = 25V) The feedback is optocoupler based. When the electrolytic capacitors in the output get older and have a greater ESR, this will reduce the ESR zero in frequency. Will this mean that its likely to go unstable? Or will the reducing ESR zero frequency a
Hello, I wish to do a flyback (non isolated) with vout = 50V, vin = 4v8, and 3W power. I don?t want to need slope compensation, so I will just use the HV9910B pwm controller from supertex (in constant off time mode) HV9910B DATASHEET I intend to regulate the Vout to 50V by using an
Hello Page 6-2 of the following has a schematic of a flyback with a UC3901 isolated feedback generator Page 6-12 onwards explains the feedback loop. ...however, i am unable to write down the poles and zeros of the error amplifier transfer i am confused by the UC3901 and
i m trying to design a isolated buck converter that will give me 5v fixed output Vin= 7v to 30V. i want to desing a pwm whose output is connected to transformer. PWM receives i/p from optocoupler which gets i/p from the output of buck converter. It would be very nice of u if u help me in this.... Thanking in advance
Hi Prashanttiyagi As Bradtherad said one of the best solutions is a buck converter . but there is another way available too . i think with this low voltage , you don't need any isolation , so a simple flyback converter , with non isolated feedback ( with two resistors and a common ground ) can be ok too . But another thing , if you use a buck con
Hi, I have a couple of questions about flyback converters. Your help in answering these is much appreciated! 1) I have read some papers in which isolated flyback operating from the AC mains, sometimes use constant on time DCM control to get high power factor. I understand why this is so. But if the output load is constant
hii, In one of my flyback smps configuration working in non-isolated topology iam using current mirror based feedback instead of using optoco upler. The circuit works fine , but under higher main voltage i.e. 40% of 230V. The trannsistor in current mirror Q2, Q3 and Q1 gets shorted which inturns destroys switcher IC. Drain and source voltage ge
hii, what would be the circuit and design parameters i need to consider if i have to design a feedback circuit using TL431 for a non isolated smps. Even though i am using a transformer. But the secondary and primary ground are common. 2. In a multiple output flyback smps, reflected voltage is secondary voltage multiplied by turns ratio.
Most commercial DC/DC modules are using flyback for multiple output modules. It's the only way to get off without secondary regulation or other multi stage designs. Input ripple can be LC-filtered. Inter-windings capacitance and respective injected interference current are a more serious problem in isolated DC/DC, I think.
Hi, what kind of level of leakage inductance could i expect to get with a standard wound half-bridge transformer for 350W offline half bridge? -Would you expect more leakage with a flyback transformer? I will have the primary sandwiching the two secondaries (+-50V) vac in = 9-265vac its an ETD44 smps ferrite core, with AL = 1024
Hello, I am trying to stabilise the isolated output voltage of this flyback converter. SCHEMATIC It is 5V, 20W at the output. (Its in CCM) (it has been arranged to be in Voltage Mode, by a ramp being interfaced to the current sense input of the LT1243) The input voltage will be 30V to 48V I
It can be used as a flyback controller. The only real difference between boost and flyback is that there is an isolated transformer instead of an inductor, and an isolated feedback network. Both of those are external to the controller IC, so the controller doesn't really care. In general a "flyback (...)
Hello, We all know that when an offline, isolated flyback goes "no-load" on its secondary, then it's bias winding drops out. ..and then the bias winding is not capable of supplying the PWM controller. Is it true , that such "drop-out" of the bias rail, can be avoided by simply adding a large electrolytic capacitor to the bias rail.?
Hello, I am doing a 43W isolated flyback V(in) = 385V (=PFC Bus) F(sw) = 67KHz Burst Mode in standby The outputs are 16V (2A6 max) and 5V8 (30mA max). These secondaries are autotransformer wound. In standby , it must draw less than 300mW from the mains. (The PFC stage , and other stages are switched off in standby) I am finding tha
Hello, I do isolated , offline flyback. TL431/Opto-coupler feedback. The problem is, the 1K resistor that's across the opto-diode to provide the TL431 bias current, places a voltage across the opto-diode of 1 Volt.... ...this in turn makes it conduct current, which is a big big problem on maximum load, because if 180uA is drawn through
Hello, I am working in the SMPS design and development department of a huge global consumer goods company (you will know the name, but I can?t say it). The SMPS?s are offline, and of powers from 5W to 200W. I am just designing a 42W offline, isolated flyback. The product is likely to be permanently connected to the mains, so it has to h
Hello, I have tested an isolated flyback with:- F(switch) = 67KHz Vout = 16V Power out = 42W Vin = 400V I took apart the flyback transformer, and the core is two "E" shaped halves The dimension of the "upright" bit of each "E" is around 2cm. Its a small core, seemingly , for 42W. The strange thing is, that there is no (...)
There are tons of applications circuits with isolated voltage feedback. Most use a TL431 as voltage reference on the secondary.
Hello, For a 230VAC offline, fully isolated flyback, what is the thickness of insulation tape required between primary and secondary?
hello. For 230VAC input , offline flyback transformers (fully isolated), how do you test to see if the transformer provides the necessary degree of isolation between primary and secondary?
I am doing isolated offline flyback of 20W... -when hand-making SMPS transfornmers, Is there any way to best wind the margin tape? (I cannot use Triple insulated wire for the primary as there's too many turns.) -is there any way to wind the margin tape evenly?....i always end up with a horrendous mess.....i don't see how it is humanly poss
hello, Can the UCC28051 be used for an offline, isolated flyback PFC supply of Vout= 36V and 53W? Its just that i am concerned about how the opto transistor links in to the UCC28051 , especially considering the 2.7V overvoltage level on the Vo_SNS pin (pin 1) UCC28051
Hello, We are doing 53W, isolated Offline flyback PFC with L6561 IC. Vin = 85-265VAC. Vout = 36VAC L6561 DATASHEET: A similar circuit for us is as figure 15, page 18 of AN1059:- However, the Overvoltage protection , as explain
Can the LT1249 PFC controller IC be used as the controller in a single stage flyback PFC converter? LT1249 Datasheet This is for a 55W PFC with 36V isolated output.
Hello, I am doing an offline, isolated, flyback with:- Vout = 36V Vin = 85-265VAC Primary Side DC Bus Electrolytic Capacitor = 68uF , 400V (Panasonic EEUEE2G680) Switching frequency = 58100KHz DC Bus cap datasheet: T
We are designing a 41W offline, isolated flyback converter (Vin=85-265VAC) for Vout = 36V +/-5% and 41W. There is going to be 30mF of capacitance on the secondary due to the fact that there must be some supply of power in the event of a mains power cut. Given that there is so much capacitance on the secondary, I assume I am right in assumi
Hello I am designing an isolated offline flyback for 28W output power. The 36V output has 30mF capacitor on it. -this is needed to provide some power to the output in the event of a mains failure. The overall spec is. flyback Fsw = 100KHz Pout = 28W Vin = 85-265VAC Vout = 36V Feedback by opto I wish to use the NCP1271 (...)