4 ms·
Some advice to the designer of this PSU: 1. It's not bad! Really, it's not. You're obviously a thoughtful designer who knows at least a little bit. Unfortunate
by exmadscientist 2y ago
Some advice to the designer of this PSU:
1. It's not bad! Really, it's not. You're obviously a thoughtful designer who knows at least a little bit. Unfortunately, you're kind of in the uncanny valley... this is better than rank amateur stuff but that gets it judged by professional standards, and it's not there by those measures.
2. Schematic pages are free. Really. They are. Use them. Put the power path on one sheet, the feedback on other, the digital on a third, the setpoint on a fourth, display on a fifth. Whatever. You get the idea. Do not just cram it all in on one. And put comments on each block saying what it's supposed to be, what else you could do (especially substitute parts), why you picked that approach, what happens if it goes wrong, et cetera. Most senior engineers don't do this. I do, and everyone always comments on how great it is when they review my work. You have some of this... (the range notes are nice!)... but go all in on this. You won't regret it.
3. Learn to decouple. 0.1uF 0805s are not the right way to do it, though they probably worked here. Look at https://www.eevblog.com/forum/projects/location-and-value-of-decoupling-capacitors-(not-bga)/msg3126270/#msg3126270 https://www.eevblog.com/forum/projects/location-and-value-of... and similar posts.
4. Mark out mains explicitly on your schematics. It should be super easy to see what is mains and what is not. This schematic is pretty good here, but this is important enough that I have to state it explicitly.
5. You have high voltage MLCCs in this design. How much capacitance are they really good for?
- magicalhippo 2y ago> How much capacitance are they really good for? Just to stress this, voltage derating is important as it can be significant. Your 10uF capacitor might effectively be just 3uF, or worse, just due to DC voltage across it. Some resources: https://www.digikey.com/Site/Global/Layouts/DownloadPdf.ashx?pdfUrl=863968494F2E4E13BBEA65B55A358443 https://www.digikey.com/Site/Global/Layouts/DownloadPdf.ashx... https://fscdn.rohm.com/en/products/databook/applinote/ic/power/switching_regulator/cera_cap_appli-e.pdf https://fscdn.rohm.com/en/products/databook/applinote/ic/pow...