I would like to create a board-to-board capacitively-coupled Ethernet copper connection from an Analog Devices ADIN1300 Ethernet PHY to a TI PHYter Ethernet PHY.
Per the linked Analog Devices user guide, this a capacitively-coupled connection is permissible between ADIN1300 PHYs and supports auto-negotiation: ADIN1300 and ADIN1200 with Capacitive Coupling [Analog Devices Wiki]
However, per the linked TI app note, it is recommended that auto-negotiation be disabled with capacitively-coupled interfaces: AN-1519 DP83848 PHYTER® Transformerless Ethernet Operation (Rev. A) - "Therefore, it is recommended that transformerless operation be restricted to forced 100 Mb/s modes, with autonegotiation disabled."
My board-to-board interface will sometimes be paired with other Gigabit PHYs, so auto-negotiation must be supported. I would like to understand the underlying circuit-level mechanics of why auto-negotiation might sometimes not work in TI Ethernet PHYs. Is there information that TI can share that would allow me to design a generic capacitively-coupled interface?
