• State Resolved
  • Locked Locked
  • Replies 7 replies
  • Subscribers 65 subscribers
  • Views 482 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM5022: EMC question

Maurizio Porro
Prodigy 200 points
Part Number: LM5022

Hello,

I need to use the  tidrdz3.pdf solution in my application for an output of 24 VDC isolated.

Also I need to make an output of 12 VDC (isolated too) and I saw the snvr063.pdf: can I join in this solution the isolation circuit used in the tidrdz3.pdf ?

The GND of the 2 output of 24 VDC and 12 VDC cannot be joined !

Another question:

in order to maximize the EMC performances of this circuits, can you suggest me some kind of precautions to obtain that and where I must put them ? I mean ferrites or similar.

Thank you

Best regards and best wishes.

Maurizio Porro

  • 0
    TI__Mastermind 21565 points
    Hi Maurizio:
    Thanks for choosing the TI part.
    The expert of this part is on holiday will address your issue after the new year. Please wait in patience.
  • 0
    Prodigy 200 points
    Another question is:
    in tidrdz3.pdf the frequency is 130 KHz, in snvr063 is 600 KHz.
    Can I increase the frequency at 600 KHz in order to improve the EMC performances?
  • 0 in reply to Maurizio Porro
    TI__Mastermind 21720 points
    Hi Maurizio,

    Can you please let me know what designs you are referencing? The PDFs are not linking or attached to the messages.

    Also what are your application specifications? VIN range, VOUT, IOUT, switching frequency...

    Thanks,

    Garrett
  • 0 in reply to Garrett Roecker
    Prodigy 200 points

    APSSModule4.pdfHi Garrett

    I'm referencing about original TI documents that I put now in attachment.

    I join a schematic of the power supply of my application that I'm developing.

    VIN = 18 to 56 VDC

    With this input supply I need to have two output isolated:

    VOUT1 = 24 VDC   IOUT1 = 1 A  (for this output I think to use the tidrdz.pdf solution)

    VOUT2 = 12 VDC   IOUT2 = 2 A

    For VOUT2 I'd like to use  a solution similar to the tidrdz.pdf, changing some components, of course: in particular I'd like to use a not custom transformer.

    In the APSSModule4.pdf file I tryed to implement something, but I'm not sure about TR2, for example.

    The switching frequency is not constrained.

    It is very important to insert ferrites or similar to avoid problems with EMC testing: I'd like a lot to have advice for that too.

    Please can you take a look to my APSSModule4.pdf file to check if it is correct ?

    Can you suggest me some precautions to maximize EMC performance please?

    Thank you very much for your support.

    Please tell me if now you can see fine the 3 attached files.

    Best regards.

    Maurizio Porro

  • 0 in reply to Maurizio Porro
    Prodigy 200 points

    Hello,

    I would ask you if, when you can, you can answer to my questions about LM5022, because the customer need to realize the PCB, to start the testing of the entire system.

    We are a bit in hurry for that.

    Thank you very much for your support.

    Best regards.

    Maurizio Porro

  • 0 in reply to Maurizio Porro
    TI__Mastermind 21720 points
    Hi Maurizio,

    To find the correct transformer please follow this design guide in section 3.1. This provides a generic way to select a flyback transformer. You can find a stock transformer that is close yo you calculated values for a magnetic vendor.
    www.ti.com/.../snva761.pdf


    Regarding EMC I would suggest adding a PI filter to the input of the board. This will allow for tuning of the filter to help pass EMC. Other than that the standard circuits like snubbers and gate resistors are in the correct position.

    Thanks,

    Garrett