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WEBENCH® Tools/TPS61022: bug report boost converter instead of a buckboost converter

Jan Bock
Expert 3025 points
Part Number: TPS61022
Other Parts Discussed in Thread: TPS61230

Tool/software: WEBENCH® Design Tools

Hi,

I have found a bug within webench. I was looking for a buck/booster based on a request of a customer: 

Vin=3.0-4.8V

Vout=3.3 V

Iout=2A

Webench suggested the TPS61022RWUR 3V-4.8V to 3.3V @ 2.5A

https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=E3DB42C102A0E39F

Since this is just a booster it should't not work out. 

Can you please have a look on it. 

Thank you!

Best regards,

Jan

  • 0
    TI__Mastermind 34231 points

    Hi Jan,

    Thanks for reaching out. 

    I'll loop WEBENCH team to look at this case.

  • 0 in reply to Zack Liu
    TI__Expert 5760 points

    Hi Jan,

    Device TPS61022 supports pass through mode for Vin>Vout. For the condition mentioned above at VinMax of 4.8V and Vout of 3.3V,device operates in

    Boost pass through mode and hence design is getting created.This is expected.

     kindly revert back to us in case of any further queries.

    Thanks and Regards,

    Umayal

  • 0 in reply to Umayal Ramanathan
    TI__Expert 3025 points

    Hi Umayal,

    Thanks for the answer. Can you explain why this is a expected behavior. I mean if I'm looking for a device which should have constant 3.3V output and I have an input range of 2-5V, musn't it be a buck-boost topology to achieve my requirements? It is somehow confusing that a booster is getting suggested. I saw the same case in the datasheet of TP61230. Under 9.2.2 you find an example configuration with input of 2.8-5.5 V and a constant output of 3.5V. If I try to simulate this with webench it is not working because it is a booster, what meets my expectation.

    Thank you 

    Jan  

  • 0 in reply to Jan Bock
    TI__Expert 5760 points

    Hi Jan,

    A typical boost converter like TPS61230 doesn't create design for  Vin>Vout as it doesn't support pass through mode.

    But since device TPS61022 supports pass through mode it allows design to get created for Vin>Vout .

    For the condition mentioned above VinMax is greater than Vout ,device operates in Boost pass through mode at VinMax.

    In Pass-Through mode, Vout is not regulated to the set Vout, instead Vout is Vin with the drop across the FET’s on-resistance and the DCR of the inductor. 

    Kindly refer section 7.3.5 of TPS61022 datasheet.

    kindly revert back to us in case of any further queries.

    Thanks and Regards,

    Umayal