Working on a power supply design, some of these integrated buck/boost all-in-one dc/dc switching supplies have selectable switching frequency and some can synchronize to an external clock.
What benefit can be found from synchronizing my switching supply to my system clock (or fraction of)?. For references there is only one clocked ic in my device (a DDS chip) and the rest are either asynchronous logic or just basic analog components.
I'm specifically looking at the LTC3115(datasheet) as my master regulator, with daisy chained 79/78XX style linear regulators for the rails.
Best Answer
If your switching power supply frequency is close to your system clock but not exact, you could get mixing (from nonlinearities), perhaps causing interference in your signal band in analog circuitry. Usually it's the difference ("beat") frequency, not the sum, that can come to haunt you.
Mixing is a nonlinear operation (multiplying) and the sum and difference signals derive directly from the trig identity:
If they're synchronized, usually such problems will be minimized (perhaps a DC offset at worst).