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SauceBoss , 01-27-2022, 04:55 AM

AlexanderBrevig , 01-28-2022, 04:01 AM

Hey! Looking good! Some opinionated feedback:

• U100 is seemingly missing a capacitor on VOUT. It is such a strong convention to show the cap there as datasheet says minimum ~1uF, a peer designer would probably flag this (you layout makes sense, but maybe move one the 10u bulk from the VDD of U104 to U100 just for looks? This is 100% just an opinion, based on my understanding of best practices).
• I am uncertain if VCC1 VCC2L and VCC2R really benefits from being regulated separately? I would imagine it being more important that they are at the exact same voltage potenial, rather than trying to isolate them from each other but I may be completely wrong about that! Just my intuition sounding a soft alarm.
• U201 should be flipped about the X axis. it seems a bit odd to have the negative supply pointing up. Nitpicky detail, I know. If you want the phase to stay inverted (corrected from IV), then maybe just swap the IOUTL+/- labels?
• For a product I would add some reverse polarity protection, and TVS diodes where people may touch (your headers, and connectors) but for a project at home, you could just be careful and take precautions
• I have no input for the layout, seems like you did a really good job!
• Your future self would probably appreciate some silkscreens explaining the connectors, label GND so you don't reverse the polarity
• For the 3d render I would definitly add the missing 3d components, for me it's like the icing on the cake, and makes enclodure prototyping easier too as a STEP export will help you figure out your mechanical requirements

Awesome job, thanks for sharing! I am done with the schematic capture of my project. Will start layout soon, hope I can do as good of a job as you've done

phils-lab , 01-28-2022, 04:23 AM

Hi there,

Thanks for sharing your project - looks pretty good so far!

I agree with all of Alexander's points and would like to add some of my own comments:

Schematic

• Instead of using 'global' net labels, I'd recommend using power ports/flags for voltage rails.
• Place designators and component values horizontally, so people don't have to turn their heads when reading the schematic.
• Section your schematic using bounding boxes or separate pages (power supplies, DAC, etc.).
• Place component designators right next to the relevant components (see: R100 to R103, for example).
• Text of 'U104' and 'PCM1795' is covered by wires.
• Don't use junctions (nodes) with 4 wires, instead use multiple junctions with a maximum of three wires coming out. (E.g. C102 + GND connection).
• Headers and connectors should (ideally) have at least GND pin per signal pin.
• VDD doesn't tell me what voltage this is at (I can see of course from the regulator what that is, but why have that extra step)? Use +3V3 instead, same goes for VCC.
• IOUTL+ goes to -ve terminal of difference amplifier, IOUTL- goes to +ve terminal. --> Flipped (see datasheet)!
• Add ESD protection, even if unpopulated.
• Why the jump from output of opamp (OUTL) to connector (OUTL). Just draw a straight wire and add net label.

Layout

• Some trace spacing can be increased, you definitely have the space for it.
• Thicker traces for power rails (e.g. from -15V and +15V).
• Silkscreen definitely would be recommended. Which connectors are input/output, power/etc.? Without the schematic/layout, we don't know.
• Why leave designators on silkscreen only for J101 and J103?
• The headers are in 'interesting' positions. Why not move the two-row headers out to the board edge?
• Copper pour on input power (-15V, +15V) caps is interesting but not really required. Through-hole connection from caps to internal ground planes is sufficient.

Good job otherwise though - I'm looking forward to seeing an update on this!

Phil

SauceBoss , 01-29-2022, 10:30 AM

Thank you both for your feedback! The project went through some changes, and I haven't done a proper cleanup of schematics. My bad. good idea about labeling voltages with values, not with names. It makes it much easier. I'd like to address some points you both made @AlexanderBrevig @phils-lab

• I'm actually going to test if separating analog VCCs makes a notable difference on this particular board
• Render is actually a bit old: I've added silkscreen names for important parts
• I've found out about reversed polarity some time ago but decided to roll with it as it suits this layout (inverting in SW will fix that)
• Signal headers are placed like that on a purpose: audio source and ucontroller will be different boards and it will be easier for me to connect them like that.
• Added lots of stitching vias

I'll add ESD protection and clean up some of the schematics. I need to design some other boards before making an order, getting just those is not economical at all because of the shipping cost. I'm thinking of some sort of balanced headphone amplifier with OPA1622, but the VSON10 package is scary...


​​​​​​​Also @AlexanderBrevig good luck with your project, will you show it to us later?