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Search for buck converter by efficiency for a given Vin, Vout , current

Stephen Turner
Genius 3416 points
Other Parts Discussed in Thread: TPS566231, TPS566238

Hi,

Is there a way to search for a buck converter with efficiency being one of the parameters?.  

For instance I'd like to find all TI buck converters that have an efficiency of >90% for Vin=3.3V, Vout = 0.8V and I = 2A, without having to go though and look at the graphs of each datasheet.

thanks!

  • 0
    TI__Genius 16530 points

    Hello Stephen,

    Thank you for reaching out.

    You can sort efficiency option, while selecting the products in ti.com

    I you can select in features about the efficiency for light load for example, but I don't think you can specify the number.

    ti.com - Buck converters (integrated switch) product selection | TI.com

    Other way you can use Webench, where you specify your requirements  and select the best device for high efficiency.

    Webench - Power Designer (ti.com)

    You can also specify your requirements here and your end application. I will help you in selecting the right device based upon your application.

    Thank you,

    Regards,

    Moheddin.

  • 0 in reply to Moheddin Pasha Shaik
    Genius 3416 points

    Hi Moheddin

    I did as you suggested and Webbench came up with the same converters as I had already found - this is the TPS566231 or TPS566238.  What's your opinion on these?.  My only concern is availability (or lack of)

    thanks

  • 0 in reply to Stephen Turner
    TI__Genius 16530 points

    Hello Stephen,

    The converters you choose belongs to different product line, I will assign to the respected product line and they will support you.

    Thank you,

    Regards,

    Moheddin.

  • 0 in reply to Stephen Turner
    TI__Expert 7320 points

    Hi Stephen,

    I have found the efficiency of TPS566231 @3.3Vin 0.8Vout 2A is 81.2 as below which doesn't meet you requirement

     You can find your answer at this link, select converter and the efficiency limitation and choose one product as below.

    Athos

  • 0 in reply to Athos Zhao
    Genius 3416 points

    Hi Athos,

    It seems if you select the low cost design you get 81% efficiency.  The high efficiency one gives 88%.  However thats when the input voltage is constrained to 3.3V. 

    If you allow the input voltage in the simulation to range from 3V to 12V , you get a different efficiency for 3.3V (90.4% vs 88.3%).  Weird.  Also 12V->0.8V is more efficient than 3.3V->0.8V.  I would not have expected that.  Can you explain?.

  • 0 in reply to Stephen Turner
    TI__Expert 7320 points

    Hi Stephen,

    It's a normal behavior of buck converter.

    You can also find the below plot in the datasheet that the efficiency is 5Vin>12Vin>3Vin when Iout>1A, which matches the result in WEBENCH.

    The two main causes of power dissipation in a DC/DC converter are MOSFET conduction losses and MOSFET switching losses.

    As the input voltage increases, the duty is lower and On-time is shorter. You can see the high-side MOS Rdson is higher than the low-side one(20m vs 10m), so the conduction losses is decreasing when input voltage is increasing, and the efficiency is higher.

    Regarding the case, are you sure to use TPS566231 even though the efficiency @3.3Vin is 88%<90%?

    If so, I think the product is suitable for your application.

  • 0 in reply to Athos Zhao
    Genius 3416 points

    Actually my main P/S is +12V and I was thinking I'd need to have a main 3.3V buck which then fed the 0.8V buck.  If I can go directly from +12V to 0.8V with >90% efficiency then that is ideal.  Thanks