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LM5141-Q1 efficiency question

d_zero
Genius 4775 points
Other Parts Discussed in Thread: LM5141-Q1

i think i found some odd things regarding the LM5141-Q1 efficiency.

The parameters:

input voltage: 12V

output voltage: 5V

output current: 5A

freq: 2.2MHz

here is the data from datasheet(page 9):

here is the data from WEBENCH:

As we see in the WEBENCH the efficiency from 1A to 5A is always grater than 90% and in the datasheet is around 80 % for given parameters.

This is a huge difference.

Please can You confirm which data is correct?

Best Regards,

David.

  • 0
    TI__Expert 3545 points

    David,

    They are both correct.  The efficiency plots in the data sheet are measured data from the EVM that you can order online.  The components used in the EVM are automotive grade component. The efficiency plots in Webench are calculations. The components used in the Webench calculations are not the same components used in the EVM, specifically FETs and inductors, so the losses are going to be different.

    Terry

  • 0 in reply to Terry Allinder
    Genius 4775 points
    Dear Terry,

    I tried to simulate the EVM board in the WEBENCH to see if I get similar results as on the EVM, and I got stuck on the Transistor part.
    I can't change the M1 and M2 to SQ7414AEN-T1-GE3 because there is no alternate part with this name and I can't create custom transistor.

    Can you please set the simulation in WEBENCH with parts from your EVM or guide me how to do this?

    Best Regards,
    David.
  • 0 in reply to d_zero
    TI__Expert 3545 points
    David,
    The SQ7414AEN model is not in Webench. The only alternative is to use an available Webench models that has a similar Rdson, Qg, and COSS and used them. Simulations of efficiency are not always exact, so it is always best to used measured data.
    Terry