On 12/5/2016 12:00 PM, [email protected] wrote:
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.
I would guess at 200mA the switcher is still operating PWM. With that tiny little inductor, the inductor has probably fallen into discontinuous current mode. Usually this is bad for noise generation. It would be interesting to see what a scope trace of the switched leg of the inductor looks like in both cases.
Dan _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
