Capacitor design issues for buck boost and flyback converters

To aid capacitor design for the most common topologies of switched mode power supplies, that is buck boost and flyback converters, an analytical approach to determine the RMS value of the ripple current and the peak-to-peak value of DC ripple voltage of the output capacitance is presented for the entire operation range. Hence the presented formulae facilitate capacitor design for this common DC-converter topology in terms of competitive aims such as maximum life cycle and minimal voltage ripple versus minimal cost and space.