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Original question:

SLVC225 - Creating a Split Rail Power Supply from a Step-Down Regulator Excel tool unavailabe?

TPS54160A: Which is correct, application report or excel tool?

haruki okumura
Prodigy 60 points
Part Number: TPS54160A

Please elaborate on the following discrepancy:

1-1) In SLVA369A–October 2009–Revised October 2012 Eq 13 and 15 use (2*Fsw*Lo) as a denominator. In the excel file, however, formulas in C73, C75 lack the multiplication by 2 (ex. ...(B53*C68))

1-2) On the other hand SLVA369A states that

The rms currents for the inductor windings
from Equation 16 and Equation 17 are 0.742 A and 0.388 A, respectively

These are the results in the excel file as well (C76,C77). So application note and excel file agree on the results. It will not be the case if the excel file actually uses the formula proposed by the app note:)

2-1)Equation 26 uses (-Voneg / Lo) as the numerator. However, in the Excel file, the C88 formula uses ((Vopos-Voneg) / Lo).

Which is correct? Please teach me.

  • 0
    TI__Genius 13735 points

    hi, 

    I suggest to use the tool for your design, and we also have a webench, you can use webench for the SCH design. And what this difference make some influence in you design ?

    Elena

  • 0 in reply to Elena Gao
    Prodigy 60 points

    hi Elena,

    Thanks for the reply,

    The formula in the Excel tool is correct, correct?
    We will proceed with the design based on the Excel tool.

    It is an additional question.
    WEBENCH was not able to simulate the Split-rail Power supply of the TPS54160A.
    Only the normal Step-Down configuration can be found.

    Is there a way to verify the TPS54160A Split-rail configuration with WEBENCH?

    Please teach me.

  • 0 in reply to haruki okumura
    TI__Genius 13735 points

    hi, Haruki,

    Sure, you could design your SCH first and use Webench or spice model to simulation. Also we have a EVM demo it's a very good reference.

    But Split-rail Power supply, webench do no have ,how about the spice model ,not sure if it could help you.

    Elena