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Off the shelf Transformer selection for Flyback DC/DC converter

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Mr.Cool

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i am wondering how to select an off the shelf transformer so it will meet my DC/DC converter needs.

let's say the only information i have is this transformer datasheet by Wurth Elektronik part number 750813134. This is a flyback transformer so i assume it is gapped and has "large" inductance which is good. its just an example, the one i think most likely to succeed, but if you have other off-the-shelf transformer better suited please let me know.
https://katalog.we-online.de/ctm/datasheet/750813134.pdf

i plan to use TOPswitch device to control converter so i don't care if is in continuous or discontinuous mode as the control chip takes care of the needs.

application specs:
Vin: 60V to 180V
Vout: 12V
Power: 12W
switching frequency: 132kHz (per topswitch datasheet)

when i follow Topswitch proceedure for converter design the equations are all geared towards finding the parameters you need so you can design your own transformer. but i dont want to design my own, i feel that there are a lot of transformers out there off the shelf, perhaps one is suitable for me?

my feeling is that the answer has to do with volt-second product and avoiding saturation of primary side inductance.

any help?
 

Since I'm the kind who likes to experiment with simulations, I made one using your specs.

Your transformer ratio can be 8:1.
Although a flyback is normally designed for a 50% duty cycle, you have some leeway to make adjustments.



The primary needs to be a certain Henry value, so that it admits sufficient current during the first half of the cycle (132 kHz).

When you apply a 60V supply, you are drawing pulses of 429 mA, at a 64% duty cycle.

When the supply is 180V, you can draw slightly fewer mA, at a shorter duty cycle.

Notice your output capacitor must carry current bursts of several A.

My schematic has a few resistors which are there so the simulator won't make convergence errors. They are unnecessary in a real circuit.
 

thx Brad. matches my own thinking.
 

It appears that the transformer you've selected has merit for the proposed application.

At one of point of time, you will have to build a physical board and validate the design. I would watch for core temperature rise, and review the waveforms (specially the primary current) to ensure that it does not saturate under boundary conditions.
 

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