Werner Almesberger wrote: > Joerg Reisenweber wrote: > >> * C4119..22, +..28 move to other side of choke >> > > This change is in ECN0038, which has been in "execute" for a while. > Rene, do you want to implement it ? > >
This is on my to-do list but unfortunately I couldn't find time to do much work on gta02-core in the last couple of weeks. Hopefully I'll have some spare time to catch up during the upcoming holidays. > >> thought we go make that path symmetric like formerly done >> anyway, so r4303 mustn't 0R >> > > Indeed. What happened with that ? > This one is on my to-do list as well. (new ECN) IIRC, we agreed to change R4303 & R4305 to 1k each. However, I just saw that R4303 and R4305 are 2.2k in the big-C buzz fix, so I would suggest to stick to those values. We know for sure that this works and the higher the resistance the better the noise performance. > >> c4307 is a nonsense, even to have pads for it. Remove C4307 footprints >> Indeed, this cap is not useful at all. >> we should replace (A)-R4305-(B) by (A)-R4305-(X), (X)-C4306_NC-(GND), >> (X)-R4399_0R-(B) >> move C4303, C4304, R4305 next to wm8753, behind B3005 >> I think that's a really good idea. In this configuration you completely prevent RF from getting into MICBIAS through JK4401. >> *make B3005 (and B4105, B3004) look like decent C-L-C filters, like e.g B4419 >> > > Having caps on each side of the chokes will definitely harden the audio subsystem against EMI and is probably a save move. However this will add another 9 components to the schematics in an already crowded area. So I'm not totally sure if that is really necessary. >> *kill R3004, R3005 finally! >> > > Okay, let's kill them. > >> *c3017 -> 1uF ? >> > > Agreed! > >> *c3003 AND c3008??? Seems we don't need both >> c3002 same >> > > Looks like the usual HF/LF pair, with the 100 nF cap right next to > the chip and the much larger 10 uF cap at some distance. > > Wolson recommends to have a 100nF decoupling cap for each power supply pin, which leads to multiple 100nF caps on the power rails of the codec. Actually, there is one 100nF cap missing. DVCC_CODEC is connected to 3 pins however only two 100nF caps are in the schematic. >> do we need B3001?? >> > > I'm not sure. Neither side of the bead should be infested with RF noise. > If in doubt, I'd keep it. > > I'd also keep the bead, just in case. _______________________________________________ gta02-core mailing list [email protected] https://lists.openmoko.org/mailman/listinfo/gta02-core
