PoE Shield

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.
  • R9 at 1Ω (through hole) regulates alright at relatively low load.
• 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.) Fixed by swapping R9 0.33Ω loop of wire for 1Ω through-hole resistor. See note about 1Ω resistor.
• CS Resistor/Capacitor Filter needs to be right next to LM5070 to minimize induced noise.
• INT jumper has no silkscreen.

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