What this octal Ethernet switch does on the board
The MAX4890EETJ+ is an octal SPDT (single-pole double-throw) switch, configured as a 2:1 multiplexer/demultiplexer across four channels. Each channel routes one of two differential signal pairs to a common port, making it a LAN switch for 1000BASE-T Ethernet. The -3dB bandwidth of 650MHz comfortably covers the 125MHz fundamental and its harmonics required for Gigabit Ethernet signaling, so the switch does not roll off the eye diagram on a 1000BASE-T link. On-state resistance is 5.5Ohm maximum — low enough that the series impedance does not degrade the return loss budget on a 100-Ohm differential pair, but high enough that the switch should be placed after the magnetics, not between the PHY and the line.
Supply rail and temperature grade
Single supply range is 3V to 3.6V, matching a 3.3V rail common in networking equipment.
The part is supplied in tube packaging. For volume orders, reel packaging may be available — confirm the packing option at quote time.