WHD12501G 10/100BASE-TX LAN Transformer

The WHD12501G has a 14.00 × 7.70 mm body, 6.00 mm ±0.50 mm high, with 10.00 mm between the two pin rows.

The WHD12401G in the same family stands 7.50 mm Max, about 1.5 mm taller, on a shorter body. 100M ports turn up in small industrial equipment and at board edges, where vertical clearance is often tighter than on Gigabit designs — the WHD12501G is one of the lower-profile options here, worth considering where a chassis lid or a board above sits close.

The WHD12501G and the WHD12503G match on outline, row spacing, pitch and span; two things differ — lead length, 3.00 mm against 3.30 mm, and the internal pin definition.

Either part therefore drops into the same holes without resistance, and nothing mechanical distinguishes them. Treat a change as a change of part rather than of package, and confirm the connection against each drawing before reworking the board.

No. Inductance, leakage, DC resistance, turns ratio, insertion and return loss, cross talk, common-mode rejection and isolation match item for item across the 12-pin parts in this family, and the WHD12501G is no exception.

Selection here therefore ignores the electrical table entirely and turns on outline, height and temperature grade. Body size and row spacing are neither of them listed in the spec fields on the 10/100 BASE-T range pages — they come only from the drawing, which is exactly where parts in this family get confused.