PoE Shield

From Hackstrich
Revision as of 23:02, 1 December 2010 by Lisa (talk | contribs) (Notes from Rev. 1)

The PoE shield will be compatible software-wise with the official Arduino Ethernet Shield, but also supply power to the board via 802.3af-2003 compliant Power over Ethernet.

Project Status

Design, BOM, schematic, and PCB layout complete, PCBs and parts received, revision 1 board assembly is in progress. Power side assembly done, data side done except bypass caps and the Wiznet controller IC. Power supply side is outputting a well-regulated ~2.4v (stays in regulation under 100/200mA load), rather than the expected 12v. Troubleshooting in progress.

Notes

Notes from Rev. 1

  • Package has silkscreen already, just none on bottom of rev. 1 boards: For LM5070 library part put a notation for where pin 1 goes.
  • Fixed in revision 2: C6 footprint does not match BoM (C6 should be 0603 or footprint to 1210)
  • D2 has no silkscreen
  • Fix footprint on U2 (Pads are too far apart lengthwise)
  • Fix footprint for U3 (it's just generally wrong)
  • U3 pinout was wrong (all of the pins were in the wrong place)
  • Bigger test points (especially for prototypes), through hole especially.
  • R108 should be 0603 (but is 0402)
  • Had wrong PoE transformer (1x3.3v 1x5v windings instead of 2x12v)
  • R9 should be 0.33Ω, not 33Ω.
  • Feedback resistors R16/R17 are backwards (i think), need to flip them/retest - Flipped, correctly limits to 11.8V with zero load.
  • Under 100mA load regulation is not correct. (This follows the R16/R17 swap.)
  • CS Resistor/Capacitor Filter needs to be right next to LM5070 to minimize induced noise.

Ideas for Rev. 2

  • Could switch the main transformer to a POE13W3VERS-R (1.8/3.3/7V) or 7491192912 (3.3/5/12V) to avoid the need for secondary regulation all together