W6100-io module RX TX ESD protection

Question

Hello, we are developing a 100Mbps PoE test board using a W6100-io module and discrete Ethernet magnetics. We have experienced damage to the W6100 RX inputs during Ethernet cable insertion/removal and would like guidance on ESD protection for the PHY-side TX+/TX− and RX+/RX− signals. With the external ESD devices removed, measurements during normal Ethernet operation showed single-ended voltages relative to PHY ground of approximately 2.52–4.04V on RX and 2.12–4.40V on TX, with an average bias of about 3.3V. These measurements used ×10 passive probes with long ground leads, so measurement-induced effects on the peaks have not been ruled out. Could you confirm the permitted normal single-ended voltage range and the allowable transient overvoltage/undershoot amplitudes and durations for these four analog pins? Please also recommend the external ESD device working voltage, clamping specifications, maximum capacitance, and connection topology. In particular, is a nominal 3.3V device such as RClamp3304N suitable for this bias and signal swing, or should a different voltage rating or protection topology be used? Recommended part numbers and a W6100-specific reference schematic would be appreciated. Thank you.

Alan · Answer

Hello, and I apologize for the delayed response. First, could you please provide the circuit schematic? We have not encountered any ESD-related issues with the W6100. I believe there may be some underlying issue in the design that is causing this problem.

chrisyue · Answer

Can ESD of Vrwm (5V or 5.5V) protect IC?