US 2007/0040533 discloses in its title an input waveform control in a switching power supply and discloses in its abstract a recognition that a filter size can be reduced substantially as a power factor is permitted to deviate below unity in systematic ways. Specific, computable waveforms permit the use of a minimum filter size, given a desired target power factor. US 2007/0040533 further discloses in its FIG. 8 an output voltage resulting from an input voltage and a predefined input current and further discloses in its paragraph 0043 that, for a converter having a 200 μF output capacitor, this output voltage shows a relatively small 120 Hz ripple. The output capacitor is responsible for reducing this ripple. So, in case the output capacitor has a decreased value, the ripple will get an increased value.
This prior art disclosure is disadvantageous owing to the fact that the ripple in the output voltage is still too large. When using the converter for supplying a light source, this ripple will result in visible flicker. The prior art disclosure is further disadvantageous owing to the fact that the converter uses an electrolytic output capacitor having a relatively large value. Such an electrolytic output capacitor has a relatively short life time, especially at higher temperatures.