SMPS transformers without datasheet: how to proceed with power supply design.

Hi all,

I purchased SMPS transformers online but they did not come with datasheet. They are of several sizes: PC40/EE8.3; PC40/EE13; PC40/EE16; PC40/EE19; and more. The manufacturers do not seem to have datasheels for them. It's difficult proceeding with the power supply design.

Please, advise me on how to deal with this situation.

All contributions are highly appreciated. Thanks.

-- Akanimo.

Hi,

Well you do have the ferrite material so you can get all the specs for the core (Bs, Br, Hc etc.) on the web (see TDK PC40). You can also measure the P/S ratio, leakage inductance, magnetizing inductance etc. Depends what you are looking for..

Hope this helps.

Ken

can you measure the inductances on the various windings and the leakage (measure one winding with the others shorted)

this will give you some idea - are you able to post pictures?

Thanks Ken and Easy peasy for prompt responses.

I'm sorry I said transformers. I meant to say the bare ferrite cores (with bobbins though). I'm to wind the transformers myself.

kended said:

Hi,

Well you do have the ferrite material so you can get all the specs for the core (Bs, Br, Hc etc.) on the web (see TDK PC40). You can also measure the P/S ratio, leakage inductance, magnetizing inductance etc. Depends what you are looking for..

Hope this helps.

Ken

Click to expand...

I have looked up the PC40 datasheet. I'm going to try out the specs there and get back here with findings.

Should there be additional information for me, please kindly drop it as I'll use it on the background. Thanks.

All of the reputable core manufacturers publish datasheets.
Who is the vendor?

To design a transformer, you will require a some parameters that you won't be able to measure yourself.
Saturation flux density Bs, remanence Br, and core loss.
By the way, this last parameter, varies with frequency.

schmitt trigger said:

All of the reputable core manufacturers publish datasheets.
Who is the vendor?

To design a transformer, you will require a some parameters that you won't be able to measure yourself.
Saturation flux density Bs, remanence Br, and core loss.
By the way, this last parameter, varies with frequency.

Click to expand...

They are Chinese-made ferrite with customer feedback that they worked.

Akanimo said:

They are Chinese-made ferrite with customer feedback that they worked.

Click to expand...

I hope that you realize how preposterous this sentence is.

On your very first post, you actually said: "It's difficult proceeding with the power supply design."

And it is difficult, because you have no specifications to design with.

schmitt trigger said:

I hope that you realize how preposterous this sentence is.

On your very first post, you actually said: "It's difficult proceeding with the power supply design."

And it is difficult, because you have no specifications to design with.

Click to expand...

Hi,

That was a response to you asking for the vendor.

I don't know how it sounds to you but I am saying that from product review, other customers (people that also bought and had used the cores in their designs already) said the cores worked for them. There are no datasheets for the cores as far as I know.

All I know about these cores are that they are PC40 and EE-something.

However, because people said they worked for them, then I believe they work. I don't know how they went about getting them to work and I can't contact them to ask them for help on that.

I don't sense anything contrary in what I said. You probably just misunderstood me.

I need help to be able to use them in power supply designs even when there are no datasheets for them.

Please, if you have some help on that, render it to me. Thanks.

...its best to get a core with a datasheet

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However, if you want, , assume its like N87 or 3c94 ferrite and find a core of similar area, and calculate.
Asuume Bsat = 0.3mT.

Calculate isat = Bsat.A.N/L
.....then wind somethign up and see how it goes.....wear goggles.
Measure temp of core....check that the ferrite can handle your Fsw and deltaB without overheating.
Look at the current, see if it shows signs of saturating.
Is it flyback or Bridge that you design?

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i think EE cores are quite similar in geometry to ETD cores, and ferroxcube have datasheets for those.

treez said:

Is it flyback or Bridge that you design?

Click to expand...

I am designing a flyback Treez.

I've gotten some PC40 datasheet for the same core sizes that I have, although from a different manufacturer. I'll go with that for now to see what I get. Thanks.