WHDG72301-1G Gigabit LAN Transformer

Go by body outline, not by pin count: the WHDG72301-1G is a 65.70 × 6.50 mm bar-shaped package, while the K-coded parts are a 34.50 × 19.00 mm block, and the two land patterns are not interchangeable.

The bar needs roughly 66 mm of straight space on the board; the block occupies a near-square area. The hole sizes differ as well — ø0.90 mm on the WHDG72301-1G against ø0.70 mm on the block parts. Selection starts with the shape of the area the PCB can give. Both outlines are listed in the 100/1000 BASE-T range.

Package, pinout and electrical ratings are identical; the only difference is which side carries the common-mode choke — the WHDG72301-1G puts it on the pin 37–54 and 55–72 side, the WHDG72303G on the pin 1–18 and 19–36 side.

The footprint is the same, so changing between them needs no PCB work. Decide from the relative position of the PHY and the RJ45 on the board and from the element order drawn in the PHY reference design.

Yes. The WHDG72301-1G holds sixteen separate 1CT:1CT units, four channels to each Gigabit port.

One channel is one differential pair; two channels, one out and one back, make a pairset, so each Gigabit port is two pairsets. Cross talk between ports is held to -30 dB Min across 1–100 MHz, and every port keeps its own termination and grounding as the PHY reference design specifies. Other port counts are listed in the 100/1000 BASE-T range.