Next sheet, Ethernet. I'm puzzled about the transformer J4: First, the part indicated in the data sheet (Molex 48025-0002 [1]) doesn't seem to be pin-compatible with the part indicated in the BOM (ComWeal UDE RTF-114B8A1A [2]).
Specifically, P1 is where R8 is, P2 is where R7 is, and so on, while the internal connection of P1 corresponds to R1, that of P2, to R2, and so on. This would mean that TD doesn't connect to TD+/TD- but RD-/RD+, and RD+/RD- to TD-/TD+. If this is really the case, then what may save us here is the auto-crossover feature of the chip. Not sure if the polarity (and winding direction), which is also reversed, is important in this case. The LEDs, on the other hand, are pin-compatible. Next, the internal connection of [1] and [2] looks different from that of all the transformers Micrel recommend. I.e., Pulsec H1102 [3], Bel Fuse S558-5999-U7 [4], Bel Fuse/Stewart SI-4600 [5], Bel Stewart SI-50170 [6], Transpower HB726 [7], and LanKom LF-H41S [8]. I couldn't find the YCL PT163020 (company dead) and the Delta LF8505 (data sheet link leads to error page) they also recommend. What all of them have in common is: the parallel transformer is on the cable side and the antiparallel transformer is on the host side. [1] and [2], on the other hand, have only TD/TX that way, but RD/RX is reversed. In addition, [1] and [2] have another coil on the TX (cable) side. Are those two designs really equivalent ? Last but not least, Pulse give a circuit example on page 3 of [3]. It differs in two respects from what we have: 1) the midpoints of the coils are referenced to GND, not 3V3. 2) they don't go to the rail directly but via a (poorly drawn) pair of 10 nF capacitors. [1] http://www.molex.com/pdm_docs/sd/480250002_sd.pdf [2] http://downloads.qi-hardware.com/hardware/milkymist_one/datasheet/Ethernet/RTF-114B8A1A(023-00).pdf [3] http://ww2.pulseeng.com/products/datasheets/H325.pdf [4] http://www.belfuse.com/Data/Datasheets/S558-5999-U7-F.pdf [5] http://media.digikey.com/pdf/Data%20Sheets/Stewart%20Connector%20PDFs/SI-46001-F.pdf [6] http://www.belfuse.com/Data/Datasheets/SI-50170-F.pdf [7] Shady source: http://www.te.com/catalog/pn/en/HB726-6-VLP [8] http://www.lankom.com.tw/product/pdf/spec_LF-H41S.pdf The rest of the Ethernet sheet looks good. R31 has the small issue that it doesn't have an explicit tolerance. (Like most of the precision resistors of M1r4.) - Werner _______________________________________________ http://lists.milkymist.org/listinfo.cgi/devel-milkymist.org IRC: #milkymist@Freenode
