WHD20601G 10/100BASE-TX LAN Transformer

Four channels, split between two ports at two channels — one pairset — each.

The WHD20601G holds four 1CT:1CT units, grouped on the drawing as TD1/TX1, RD1/RX1, TD2/TX2 and RD2/RX2, each pair forming one complete 100M port. This is easily confused with Gigabit: a dual-port Gigabit part holds eight channels and four pairsets, twice the unit count. Read the data rate first, then divide by port count.

On board area one part wins: the WHD20601G is 25.40 × 10.00 mm against two 16-pin single-port parts at 20.30 × 9.80 mm each, close to half the width.

But a dual-port device ties both ports together — a fault on either means replacing the whole part — and two single-port parts leave the layout freer, letting the two RJ45s sit in different places on the board. Cross talk between the ports of the WHD20601G is held to -30 dB Min across 1–100 MHz, so isolation itself is not the deciding factor.

No. That 8 mA is the DC bias applied to the winding while measuring open-circuit inductance, used to verify magnetising behaviour — it is not current available for powering anything.

The WHD20601G is a non-PoE part with no DC supply rating on its centre taps at all. Whether a device can deliver power is settled by a separate datasheet line giving a current capability and the applicable IEEE class, not by the test condition on the inductance line. Parts with such a line are grouped in the Gigabit range.