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LM3481: LM3481-FLYBACKEVM increase in current

Mohsin Shehzad
Intellectual 280 points
Part Number: LM3481

Hi Dear,

      Can please anyone describe if I can increase the output current of the LM3481-FLYBACKEVM?

If the increase in current is possible then how much it can go above 2A with stable output voltage?

Kind regards

Mohsin 

  • 0
    TI__Guru 68335 points
    The power is limited by the peak primary current which is the highest at min VIN. In other word, in the EVM's 5V to 32V input range, the higher the input voltage the higher the load can be delivered. This is the simplest way .

    If that is not enough, you need to change a larger transformer capable of handling higher current, and smaller current sense resistor. You also need to adjust the loop compensation in accordance when changing these component.
  • 0 in reply to Youhao Xi
    Intellectual 280 points
    Hi Youhao,

    Thank you that solved my problem. My requirement is 12V and 6.5A at output with input voltage is between 10V to 20V.

    Can you please suggest that if I can reproduce this PCB in smaller size? If yes can you please suggest some reference material regarding PCB design.
    Kind regards
    Mohsin
  • 0 in reply to Mohsin Shehzad
    TI__Mastermind 21720 points
    Hi Mohsin,

    Here is an application note on how to design the LM3481 as a flyback.
    www.ti.com/.../snva761.pdf

    -Garrett
  • 0 in reply to Garrett Roecker
    Intellectual 280 points

    Hi dear, 

          Thank you for your reply.

    Due to our requirement I want to change the transformer on this board with a smaller size, can you please suggest one?

    Also can I increase the switching frequency on this board as the transformer has the specifications of working on 130KHz?

    Kind regards

    Mohsin  

  • 0 in reply to Mohsin Shehzad
    TI__Mastermind 21720 points

    Hi Mohsin,

    The easiest way to meet the application size requirements is going to be to contact magnetic vendors directly. From the application note above the inductance and saturation current of the transformer can be calculated. Once these values are known a custom transformer can be made to meet the size requirements. Typically this will be a multi-iteration design problem to find the correct trade offs of size and efficiency. Component websites also make it easy to filter through off the self products.

    Please let me know if you have any questions.

    Thanks,

    Garrett