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Understanding TPS61175’s Pulse-Skipping Function

Yanbin Zhao92331
Intellectual 490 points

4503.Pulse-Skipping.pdfIn the application report "SLVA353–July 2009", the author presents 2 formula to generate the threshold current which cause the controller entering pulse skipping mode in page 2. The application that the author use as an example is boost circuit. The 2 formulas is shown in the picture.

But I don't know how does the Equation 1 derived, anybody knows?

  • 0
    Intellectual 490 points

    I figure out the solution:

    Just Remember, for boost converter, the average energy of output stage (both output capacitor and load) origins from boost inductor, especially from switching off period of the mosfet.
    During switching off period, part of the inductor energy goes into output capacitance and others supply the load. So during one period, the average energy or current supplies the load equals to the average energy or current sent out during switching off period. This is the theory for Equation1:

    During Switching off Period: toff = (Ipeak * L) / (Vo + Vf - Vin),
    For Average Current Balance: Iload * T = Ipeak * toff / 2, [area of rectangle = area of triangle, while T=1/Fs],
    Incoporate 1st equation into the 2nd equation will generate Equation1 in "Pulse-Skipping.pdf"