The ripple requirement is shown graphically on this slide. On the left is an illustration of what happens with an inadequate amount of output ripple. The output voltage will still remain in regulation, but at the same time, operation will be somewhat erratic and the ripple will have harmonics. Also, the left image is an illustration of just an alpha capacitor with very low ESR. In the image on the right, if sufficient ripple voltage is added on the output, the result is solid periodic operation. As previously indicated, the frequency of operation will remain solid and constant throughout the operating range.