LM5021: Flyback AC/DC converter

ABHISHEK KUMAR

Part Number: LM5021
Other Parts Discussed in Thread: TINA-TI

0647.Noname.TSC

Hii..

Designing an AC/DC converter of 60 W, 19 V output but after simulation in Tina-Ti, I am not getting the proper output of 19 V. The output voltage I am getting is in nV. I am uploading a screenshot of the simulation and also the simulation file. Please check and suggest where I am doing wrong, any help will be appreciated.

Thanks.

over 4 years ago

0 Mike O' over 4 years ago

TI__Guru* 86266 points

Hello,

I reviewed the schematic and the aux winding polarity does not look correct.

I would start by using the Webench tool to check your component selection for your design. You can find it on the following page, search for Webench.

https://www.ti.com/product/LM5021?keyMatch=LM5021&tisearch=search-everything&usecase=GPN#design-development

There is a working Tina model that you can use in your simulation that can be found in the following link. Remember to adjust the transformer speciation's to match your exact design requirements.

https://www.ti.com/lit/zip/snvm452

Regards,

0 ABHISHEK KUMAR over 4 years ago in reply to Mike O'

Prodigy 120 points

Hello,

I have designed the circuit and done the simulation by using Webench circuit parameters but still not getting the perfect results. I have attached the simulation file, please go through it and suggest me, what changes should I make to get the result.

Thanks

0 Mike O' over 4 years ago in reply to ABHISHEK KUMAR

TI__Guru* 86266 points

Hello,

I will try to look into this next week.

Regards,

0 ABHISHEK KUMAR over 4 years ago in reply to Mike O'

Prodigy 120 points

Hello,

Please look into it, it's important.

Thanks

0 Mike O' over 4 years ago in reply to ABHISHEK KUMAR

TI__Guru* 86266 points

Hello,

Just got in this AM and will take a look at this when I have a chance.

Regards,

0 Mike O' over 4 years ago in reply to Mike O'

TI__Guru* 86266 points

Hello,

Do you have the Webench output so I can compare it to your Tina model?

Regards,

0 ABHISHEK KUMAR over 4 years ago in reply to Mike O'

Prodigy 120 points

Here is the Webench link for the design.

Power Designer (ti.com)

0 Mike O' over 4 years ago in reply to ABHISHEK KUMAR

TI__Guru* 86266 points

Hello,

I reviewed your schematic vs the Webench design tool.

1. C1 >> than recommended this O.K.

2. C6 and C7 >> bs the webench design tool, this is O.K.

3. R5 << smaller than recommended please correct.

4. Transformer turns ratio and primary magnetizing inductance do not match Webench tool. This needs to be corrected.

Regards,

0 ABHISHEK KUMAR over 4 years ago in reply to Mike O'

Prodigy 120 points

Have you run the simulation after correction, is it giving the correct output?? I think , No!! I have corrected the circuit parameters but still facing the same problem.