WHDG18101G Gigabit LAN Transformer

Indoor Gigabit data ports where the component temperature stays between 0 °C and +70 °C and a through-hole package is required. The WHDG18101G is an 18-pin DIP single-port 100/1000 BASE-TX transformer without PoE, so the port has to be powered locally.

A DIP package is usually chosen over surface-mount for mechanical retention under vibration or stress, or because the line already runs a wave-solder process. If the equipment must power up below 0 °C or work outdoors long term, this part does not apply. Other options are listed in the 10/100/1000 BASE-T range.

No. The datasheet assigns no DC balance current capability to the centre taps of the WHDG18101G, so they cannot be used as a supply path. Termination values and the grounding approach should follow the reference design for the target PHY.

If the design needs power over the cable, move to a part that carries a PoE current rating rather than reworking the circuit around this one.

How insertion loss and return loss are specified: the WHDG18101G gives fixed limits, while the WHDG18110G gives formulas. The WHDG18101G specifies -1.1 dB max insertion loss from 1 to 100 MHz and return loss as fixed values at five frequency points; the other expresses insertion loss as a function of frequency and, above 40.1 MHz, return loss as a formula too.

OCL, DCR, turns ratio, crosstalk, common-mode rejection, isolation and temperature range are identical on both. The difference matters in a link budget: a fixed limit can be read directly, whereas a formula has to be evaluated at your actual frequency. Both ship 30 pcs per tube.