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So, I'm tinkering with the ATtiny 3224 and its PWM capabilities. I can get 256 bits of resolution per cycle at 78.125kHz.
If I drop to 32 bits, that gets me to 625kHz, as shown in the screenshot.
I've done some searching but I may not know the right term and I'm probably looking for a rule of thumb.
What sort of resolution do you need to regulate a DC/DC switch mode? (in this case a pure resistive load that doesn't change)
I think it might be something like a factor for required percentage of change of switch ON time. Such as, you should generally be able to modify your duty cycle by increments of 5% or 0.5% or whatever for proper regulation.
Does this factor have a name?
I see, yeah that seems like a decent design going through the interrupt. Since your load is static, the responsiveness of your IC interrupts shouldn't matter too much, but if you were trying to drive a high bandwidth load, then it would start becoming an issue. 625kHz or even the effective 200kHz you have control over would be plenty accurate even for something like audio (which wouldn't change faster than maybe 48kHz). You can size your output capacitor accordingly so that if you suddenly hook up a bigger load, the voltage drop is acceptable until the IC can catch up.
Sorry, I got a little caught on other's interpretation rather than what you were actually saying.