I'm considering use of a switching buck converter to power the TEF668x tuner. I don't see data in the datasheets that identifies tolerable noise on the power supply line to maintain tuner performance. The switching power device candidates I'm looking at use selectable clocks up to 2 or 2.2MHz, and I'd choose a higher frequency to avoid obvious potential issues with AM reception. Switching noise on the power supply output is illustrated at about 7mVpp and can be improved to about 1mVpp w/ added filtering. The spectral content of that noise is about 280uVrms at the fundamental and harmonics can be up to 200-240uVrms or more in the FM band, improved to about 4uVrms w/ added filtering. Are these ripple levels tolerable to maintain tuner performance? What are tolerable power supply noise levels for the device?
