On Sun, 4 Dec 2016 16:41:13 -0500 John Ackermann N8UR <j...@febo.com> wrote:
> The little OCXO I used for testing goes from about 850ma cold to 200ma > hot (at 5V) and I noticed a very different appearance of the spectrum as > the current dropped -- at high current, the switching spurs were quite > narrow, but as the current dropped (and particularly below some > threshold I don't remember) the spurs widened out quite a bit. This is exactly the PWM to PFM mode switch I described earlier. The 850mA are probably high enough that the DC/DC converter works in PWM mode, thus switching with a constant frequency, even if the load changes. On the other hand 200mA of a 1A converter is low enough that it's most likely in the PFM region, where every small change (or noise) causes the switching frequency to change. Attila Kinali -- Malek's Law: Any simple idea will be worded in the most complicated way. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.