Possible CDE (Cable Discharge Event) Ethernet?

Thread Starter

altjam

Joined Jan 21, 2021
1
tek00002.png

Hi all. Please reference above image.

I have been having many issues with my Ethernet PHY chip. The device will be working fine. When I unplug the Ethernet cable, and go to plug it back in, that is when the failure seems to be occurring. It is sporadic, and doesn't happen every power cycle.

The above capture is the 5V rail on my device when I plug in the cable. I am relatively new at electronics, but I doubt this is normal? I came across cable discharge events that had a very similar transient response (very quick transitions between positive/negative, and similar timing).

Is this representative of a cable discharge event? We have ESD protection circuitry in place, which makes me think this could be something else entirely?
 

KeithWalker

Joined Jul 10, 2017
1,789
What is the other end of the Ethernet cable connected to?
I would suspect that one or both of the devices are not properly grounded. Can you measure a voltage (AC or DC) between the ground on the cable and the ground on the PHY chip circuit when the cable is not plugged in to it?
 
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