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SEPIC based on LM2621

Other Parts Discussed in Thread: LM2621, LMR61428

Hi,

I'm trying to use WEBENCH® LM2621 to design a SEPIC converter for the LM2621 with the following parameters:

Vin=4V - 12V

Vout=5V

Iout=500mA

However the WEBENCH® LM2621 always says "design can not be created"

I tried to change parameters with lower voltages, current etc, whenever I select inputs that should be implemented by SEPIC converter I'm receiving the same negative answer.

Is there are any bug in the WEBENCH® LM2621, because the data sheet shows me exact that it can be designed. Do you have any Application Note describing step by step how to calculate  it?

Thank you in advance

  • Hello Loannis,

    Thank you for your support using the Ti's WEBENCH Designer Tool.

    Unfortunately, the LM2621 is not configured for the SEPIC topology in WEBENCH. However, they are few devices in the tool are configured for SEPIC if you enter the input parameters into the main panel from the Ti’s main page.

    I apology that the LM2621 is currently not supported for SEPIC in WEBENCH.

  • Thank you for your answer. Do you have any application note related to the calculation of the components of the SEPIC converter based on the LM2621? One additional question is: "What is the difference between the LM2621 and LMR61428 ?" They looks like pin-to-pin compatible, are they ?

    Thank you in advance for answering for all 3 questions

    My Warmest Regards

  • Hi Loannis,

    We have app note AN - 1484 as far as SEPIC converter App notes go but nothing specific for LM2621.

    There are internal changes to reduce cost between the LM2621 and LMR61428 which make the LMR slight more cost effective. However we've qualified these changes and ensured performance as specified in the datasheet.

    They are pin compatible, one of the great advantages of using Simple Switcher. :)

    Thanks,

    Anston