ADC power supplies: linear or switching?
davidedelvento opened this issue · comments
An inconsistency in the ADC kicad file:
As you can see the comment says "Monolithic switching regulator" but the part and its description is for a linear regulator.
Probably related (hence I am not opening a separate issue for that) is the text in https://github.com/jkominek/piano-conversion/wiki/Assembly-Notes which says
IF your firmware doesn't draw much current, you can use a linear 3.3V regulator, and save a couple of dollars per board. If you don't know what you're going to run on the board, stick with the suggested VR05S3V3
Not sure what you mean by "suggested", I initially thought that your board had a switching regulator VR05S3V3 which one could substitute with linear regulator, but instead it looks like it is now the other way round? If that is the case, does it mean that the regulator you selected should be able to provide enough current for a generic firmware, or that you measured the current for the firmware you posted and for that the linear regulator is adequate?
In any case, you might want to fix the kicad file and the wiki page
I'm not entirely settled. Facts:
- I've built them with multiple different switching regulators, including the VR05S3V3 and they all seem to behave fine. (The concern is that they would generate noise that might make it into the analog domain.)
- For the current firmware, TO-220 linear regulators will work alright and the heat generated won't be a problem, even without a heatsink on them. (Linears would make little-to-no noise, but generate waste heat proportional to the current drawn. They're also slightly cheaper.)
- If you got the STM32H7 to sink the maximum rated current, then TO-220 linear regulators even with significant heatsinks would be challenged to remain "cool enough". But it is unlikely you could write a useful firmware that would draw the max current.
So, yeah, the docs aren't completely clear. I'll try to clear that up at some point.