PMP3162: Unable to Find Transformer Details!

Hi Vijay,

This part is from Pulse Electronics (https://www.pulseelectronics.com/)

I have also attached the spec sheet here.

PA4141NLrevS0.pdf

Thanks,

Robert 

Dear Robert,

  Thanks for your quick reply... But datasheet you have given is hand written notes not easy to understand how many turns in primary; how many in secondary also which cores is selected no details to remake the transformer... Also even on website https://www.pulseelectronics.com we don't find any such product. I think this design is way to old and this product transformer is probably obsolete. we cant find this part anywhere nor in mouser nor in digikey or anywhere. Maybe you can provide a similar part from pulsetransformer or some other brand? Thanks in advance. Deeply awaiting your reply.

Best Regards,

  Vijay Gohil

Hi Vijay,

I am sorry that you are having issues finding the info that you need. Unfortunately we don't have the info on the construction of the transformer, that is proprietary to the vendor. So I don't even know the number of turns, core material, etc. We give a set of electrical specifications to the vendor and they make the transformer. We can give you the electrical specs. Then you can use the vendor of your choice to make the transformer. I am also going to include the original designer send that info.

Dear Robert,

  Thanks i would appreciate the help for adding original designer. Since transformer is key component here we really need additional details on it to finish our designing.

Best Regards,

Vijay Gohil

Hi Vijay,

The most critical electrical parameters are the turns ratio of 2:1:1 (primary:secondary:auxiliary), and primary inductance of 50uH.   

Because the PA4141NL was a custom part, it is not listed on the Pulse web site.  I am contacting Pulse to see how best you can get a quote and samples.  I will reply back when I have an answer.  In the meantime, you can also try directly contacting your local Pulse representative to see if they can provide a quote and samples:  https://www.pulseelectronics.com/contact/

Please let me know if you have other questions about the design.

thanks,

Brian

Hello Brian,

  Thanks for your quick reply! Yes i ahve some questions

1. Could you tell us how did you come to conclusion for primary winding to be 50uH any specific thumb rule or formulae?
2. Which core did you use for T1?
3. For inductor in secondary L1 how did you calculate it to be 6.82uH?
4. From pulse transformer website I did select one transformer PA0905NL which is only 250W transformer I can find in stock on digikey( cant find any other models in stock like PA 0901,etc). do you think it is good for I/p: 45-95V and O/p 12V-20A it is 6T:6T:2T(P:S:A) can use it as ratio 2:1:1 as you suggested.
5. Sorry for too many question Deeply awaiting your reply. Thanks again in Advance!

Best Regards,

  Vijay Gohil

Dear Sir,

  Still awaiting your reply.

Best regards!

Hi Vijay,

1. The magnetizing inductance for this design was empirically determined during lab testing.  The amount of magnetizing inductance needed is dependent on the output capacitance of the FETs.  The magnetizing current must charge and discharge the COSS of the FETs during the switching transitions.  More COSS requires more magnetizing current (less magnetizing inductance.)  For a 48V input application, 100uH is commonly used in a 100W designs.  50uH is more common for 200W designs.  (These are just general rules of thumb.)

2. This looks like it used an EFD30 size core.

3. The output inductance is based on how much ripple current you want to allow in the output inductor.  This is exactly the same consideration and equations as a standard buck converter, but you must account for the turns ratio of the transformer to determine the voltage on the input side of the inductor.  With the 6.8uH inductor, this design will have around 6A peak to peak ripple current at 72V input.  Our Power Stage Designer tool can help you investigate the effects of changing the power stage components.  Below is a screen shot with the input-output conditions of this design.

4. The PA0908NL looks like almost an exact match for this design, except it is missing the AUX winding.  You will need to connect the primary windings in parallel and the secondary windings in series.  This will result in 54uH of magnetizing inductance, and a 2:1 turns ratio (primary:secondary). You would need to contact Pulse about adding a 2T aux winding.

I have not heard back from my contact at Pulse.  I will keep trying.

thanks,

Brian

Hi Vijay,

I have heard back from Pulse (now Yageo.)  They are working on getting PA4141NL orderable on the internet.  In the meantime, you can contact Andrew Mun Andrew.Mun@yageo.com for a quote and samples of this part.

thanks,

Brian 

Dear Brian,

  Thanks for your reply. I have written to him and lets hope i get a response soon. I would like to close this case but before I would like to ask you could you share your contact details (email/whatsapp) if i need to contact you directly?  It would really help. 

Thanks again!

Best Regards,

  Vijay Gohil

Dear Brian,

  Awaiting your reply.

Thanks again!

Best Regards,

  Vijay Gohil