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WEBENCH® Tools/TPS61170-Q1: EFFICIENCY DIFFERENCE

Nidhi Lodha
Prodigy 210 points
Part Number: TPS61170-Q1
Other Parts Discussed in Thread: TPS61170

Tool/software: WEBENCH® Design Tools

Dear TI Team,

We have developed 2 boards which use two 24V power supply designs based on TPS61170-Q1 IC ( 24V 15mA and 24V 50 mA). We simulated these using the Webench tool for a desired efficiency and followed the datasheets reference layout. However, we have not been able to achieve the desired efficiency as per the reports. The Webench design report shows an effiiency around 87% at full loadand we have been able to achieve only around 76% efficiency.Attaching the Webench design reports and also images of our layout for both the designs.

We have faced an issue in another 6.5V design as well which is in the link below wherein TI has stated that the design parameters for the webench tool were updated due to which we observed a difference of efficiencies between earlier generated reports and latest reports and observed our boards match with the latest reports.

Our concern is to how accurate are the Webench tool parameters for the 24V design using  TPS61170-Q1 IC as in the attached reports. We are investigating to know if this is also a Webench parametric issue which needs and update or is there any design recommendation which we havent followed.
We would request you to please review our report and layout and support us on it.
24V 15mA layout
24V 50mA layout
  • 0
    TI__Mastermind 40080 points

    Dear Sir,

    The Webench EFF. result is based on the calculate. I don't know how the Webench team calculate the efficiency, but if the formula is not accurate, then the result will be different with the test.

    You can refer to the efficiency curve in the TPS61170 datasheet for a reference.

    By the way, what is the Vin?

  • 0 in reply to Helen chen
    Prodigy 210 points

    Dear Helen,

    The Vin is 3V to 3.7V and all other design parameters are attached in the design reports above.

    The Webench tool models the IC's design parameters to calculate the efficiency and details are in the report.

    Concern is how accurate are these models and report results to the actual test results and since we have already faced an efficiency mismatch with an earlier IC and realised that the parameters were incorrect and updated by TI later as mentioned in the link in above post we would like TI to support us and review our 24V design and suggest if the parameters are accurate or is there any design recommendation which we havent followed to observe an efficiency mismatch there.

    Regards,

    Nidhi Lodha

  • 0 in reply to Nidhi Lodha
    TI__Mastermind 40080 points

    OK, I will check it tomorrow!

  • 0 in reply to Helen chen
    TI__Mastermind 40080 points

    Dear Sir,

    With TPS61170, You can get higher than 80% efficiency at least for Vin=3.5V and Vo=24V/50mA and around 86% at Vin=5V.  Please share the schematic you get the 76% efficiency and the related BOM.

  • 0 in reply to Helen chen
    Prodigy 210 points

    Dear Helen,

    We are interested in knowing the expected efficiency at 3.3V Vin for Vout=24V 15ma and 24V 50mA. The Webench seems to show that around 87% for Vout=24V. Please let me know is that even close to accurate?

    Attaching the schematic and BOM for both designs.

    Regards,

    Regards,

    Nidhi Lodha

  • 0 in reply to Nidhi Lodha
    TI__Mastermind 40080 points

    Dear Sir,

    I will do the bench test next week based on the EVM board.

  • 0 in reply to Helen chen
    Prodigy 210 points

    Dear Helen,

    We shall await your reply.

    Also please could you provide us some base calculations based on which you provided the efficiency estimates as above in your post for the boost converter since that's different from what the webench report calculates. We just want the calculated efficiency as per your estimates for input of 3.3V and 3V for the 24V output.

    Regards,

    Nidhi Lodha

  • 0 in reply to Nidhi Lodha
    TI__Mastermind 40080 points

    Hi Lodha,

    Very busy recently.

    This is an old part, we also don't have the calculaiton sheet for this part. I will try to work out a draft one for this part.

    Please wait in patience. Hopefully ready in  next week.