I would like to power my device via PoE, but I do not know which mode (A or B) is provided by the 802.3af power sourcing equipment (PSE). How should I design a splitter to accept both implementations:
A) the phantom power technique common with "endspan" PSEs
B) using "spare" pairs in 10BASE-T and 100BASE-TX as in a "midspan" PSE
I understand that I cannot simply connect pairs 2 and 3 for DC supply in Mode A, as I would need connections to some kind of transformer center-taps and a diode bridge, but then how would that be compatible with Mode B? This is where I need guidance.