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LM5175: lower efficiency than expected

Bruce li
Genius 5580 points
Part Number: LM5175
Other Parts Discussed in Thread: , LM5176

Dear TI Experts,

My customer is designing a new power project with LM5175, their requirments is 9~30Vin/5A, 27~42Vout/2A, after finished prototype, they measured efficiency and only got 85%~88%.

They checked LM5175EVM which can achieve above 93%, with the Vin 6~36Vin / 6A , 12Vout. 

Could you kindly help to give some advice how to improve the efficiency to above 90% ? Attached is their schematics and layout, thanks a lot.

INPUT 9-30V OUTPUT 42V2A.pdf

TTIBBMSGEN2P010.pdf

  • 0
    TI__Mastermind 46905 points
    Hi Bruce,
    the efficiency mainly depend on the power components, such as inductor and MOSFET. if the components used in the circuit is similar to the components used in the EVM. there are two version of the LM5175EVM, which one is used by customer.
    you can also measure the thermal image the power components and the IC to check which one has high power loss.

    I would suggest LM5176 for new design.
  • 0 in reply to Jasper Li
    Genius 5580 points
    Dear Jasper,
    Thanks a lot for your support. I'll check with customer about their power components details. For LM5176, is it supposed to achieve higher efficiency than LM5175?
  • 0 in reply to Jasper Li
    Genius 5580 points

    Dear Jasper,

    Checked with customer,  they used webench to generate schematics, and just changed the inductor ,below is the inductor's datasheet and screenshot of efficiency estimated by webench.

    Could you kindly help to give further advice? Thanks a lot.

    FXL1360.pdf