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TPS40211-Q1: TPS4021x-Q1 Datasheet Error?

JSly
Intellectual 410 points
Part Number: TPS40211-Q1
Other Parts Discussed in Thread: TPS40210

Hello, I'm designing a boost converter similar to the one described in Typical Application 8.2 on page 26 of the datasheet for the TPS40210. I was going through the calculations and am having trouble with Equation 59. When I put this into MATLAB with the typical application numbers, I get 0.2087. I checked with a colleague and he also gets this. Can you verify that this calculation is correct?

https://www.ti.com/lit/ds/symlink/tps40211-q1.pdf?ts=1587768910081

Thanks!

  • 0
    TI__Mastermind 19490 points

    Hi Jason,

    Thanks for using the TPS40210.

    The equation is correct based on the model that output impedance looks like a current source flowing into the output impedance (Rout) in parallel with output capacitor in series with its equivalent resistance (Cout+R_esr).

    Output impedance looks like [(R_esr+1/(s*C_out)]||R_out].

    I think in this design, this could be thought of a scaling factor or through experimental results.

    Ideally, you would get the value around 0.2 through the equation above, but empirical results will give another value.

    The equations given here can be thought of as a guideline based on some approximation/model, but will need tweaking or testing in order to produce optimal results.

    Thanks,

    Richard