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LM5175: lm5175 schematic review for 24V 3.5A Output

Ritchie Hua
Prodigy 30 points
Part Number: LM5175

Hi TI support,  

I am planning on designing a 24V 3.5A supply from the LM5175 chip. 

I have based most of my calculations on the LM5175 datasheet and the web bench.  
Could you please review the following schematic if there are any glaring mistakes? 

Thank you for your time.  

Regards, 

Ritchie 

  • 0
    TI__Mastermind 46341 points

    Hi Ritchie,

    thank you for using the E2E forum.

    For more accurate review can you please provide some more details:

    - input voltage range

    - Inductor parameter: DCR, Saturation Current

    By the way: another great tool is the Quickstart Calculator which allows you to get and set the values on a specific device:
    https://www.ti.com/tool/LM5175QUICKSTART-CALC

    Using that it looks like the compensation is on the margin of a good stability. So this could be improved but would be also good to test and optimize on the final board.

    Best regards,

     Stefan

  • 0
    Prodigy 30 points

    Hi Stefan,  

    The input voltage is 6-36V 

    The inductor is a MWSA1205-4R7MT
    datasheet.lcsc.com/.../Sunlord-MWSA1205-4R7MT_C149572.pdf
    DCR = 9mOhms
    Isat=21A 

    If you have the time, could you also review my 4-layer PCB layout for another LM5175 conditioning board. 
    Vin=6-36V, Vout=12V, Iout=6A. 
    The schematic is based on the schematic from the datasheet and I tried to follow the layout example as closely as I could.  
    I plan on using this layout to layout the 24V output board.  

    Best Regards, 

    Ritchie 

  • 0 in reply to Ritchie Hua
    TI__Mastermind 46341 points

    Hi Ritchie,

    thank you for the additional information.

    The schematic looks good but as already mentioned in the previous mail the compensation loop seems not to be adopted for this design and might become unstable. For the initial testing i would recommend this values.

    C8 18nF

    R3 2.1k

    C9 68pF

    But also recommend to do a Bode plot with the real design and test for the stability again.

    Yes, i can also review the other design but would recommend to open a new thread for that.

    Best regards,

     Stefan

  • +1 in reply to Stefan Schauer
    TI__Mastermind 46341 points

    Hi Ritchie,

    did you get all the required information?
    If the issue is solved it would be great to press the is solved button.
    If there is still something open, just let me know with the new details.
    Best regards,

    Stefan