I am looking for suggestions on protecting a gigabit ethernet port from ESD between the jack and the magnetics.
Due to the nature of the equipment design, the magnetics cannot be placed next to the non-standard (ie not RJ-45) circular connector. The transformer is about 3 inches away after the signals traverse a flex and onto a PWB. Currently using a Semtech Rclamp0524 device on the flex right at the connector for the high-speed Low-C ESD protection that doesn't affect the eye diagram of the PAM-5 differential signals.
However we have found that when connected to some network routers/switches with PoE (which tends to be turned on by default on those pieces of equipment) the TVS diodes get destroyed (sometimes short -> port quits working, or sometimes open -> port works but now unprotected). The theory is that the V/I characteristics on these during the PoE probes makes the port look like there is a PD controller on it and the PoE runs the voltage up and destroys the diodes.
We are going to move these TVS diode arrays to between the transformer and the MDI/PHY port to protect the phy. However I also need to protect the other circuitry on the PWB (near the flex interface) from seeing the ESD transients (every other interface port has ESD protection right at the back of the mil-circ connectors to keep it off the main PWB). The concern is that any TVS capable of withstanding PoE voltage has too much capacitance and will degrade the eye diagram to the point that 1Gbs operation won't work.
Does anyone have recommendations for parts and/or an alternate solution that could be used to kill ESD on the flex/connector circuit?