WHDG30102G 10/100BASE-TX LAN Transformer

The WHDG30102G and the WHDG30101G are two separate part numbers, not revisions of each other; their electrical figures, outline dimensions and hole pattern nevertheless match item for item, and only the internal running order differs.

On the WHDG30102G schematic the common-mode choke and the transformer sit in the reverse order to the WHDG30101G drawing. That does not change the external electrical behaviour — every electrical item is identical on both — so there is no "which performs better" question between them. Both sit in the 10/100 BASE-T range.

Yes. The three transformer groups inside the WHDG30102G are independent, so leaving one unconnected does not affect the ports that are wired.

The trade-off is cost: a triple-port part takes the board area and the price of three ports, and using two wastes one of each. The deciding question is whether the board keeps headroom for a third port. Terminate the unused group in the normal way rather than leaving the traces floating. Dual-port alternatives are listed in the 10/100 BASE-T range.

No. The WHDG30102G electrical block runs to eleven items and none of them states a current capability or an IEEE power class.

The 8 mA in the datasheet is the DC bias applied while measuring open-circuit inductance, used to verify magnetising behaviour — it is not current available to a load. Whether a part can deliver power is decided by a separate line stating current capability and the applicable IEEE class. Where a port has to be powered over the cable, move to a PoE part during selection; the capability cannot be added later. PoE parts are listed in the 10/100 BASE-T range.