Ethernet PHY is required in every microcontroller application which uses ethernet interface. It consists of RJ45 connector, transformers and PHY controller, which is analog circuit – interface between transformers and ethernet controller in microcontroller.
Circuit is divided in two PCB to keep it simple and single-sided. It connects via 20 pads (2,54mm raster) in dual row. Ethernet cables are usually stiff. Dual-in-line style of this module provides better mechanical rigidity.