Ethernet IC (W5500) functional issues - Page 1
Forum section: electronics / general

author: aakash dey
author_rank: Contributor
timestamp: May 09, 2020, 03:15:53 am
content: I am using Ethernet module, W5500 in my circuit. The schematic is attached.I noticed that the Link LED stays static but whenever I restarts the AC supply switch sometimes the Link LED restarts. This is not frequent but unusual.Our device runs on both AC and rechargeable battery power. Every-time when continuously I turn ON and OFF the AC power for 5-10 times it occurs(Link LED restarts) once. When it is on battery power it also happens.(May be the link is getting disconnected and restarting) I have also checked the supply which doesn’t fluctuate at that moment(3.28V).I have done some experiment on this. Below are the observations of the experiment:During the restart of the link led, the fraction of seconds for the which the LINK LED turns OFF, the voltage level of the LINK LED pin of the Ethernet ic changes from 100 mv to 3.3V. After that, when it glows again it again come down to 100mv. In the whole process the, the voltage level at the reset pin of Ethernet ic is unchanged (2.8V).I am using Ethernet module, W5500 in my circuit. The schematic is attached below: enter image description hereI noticed that the Link LED stays static but whenever I restarts the AC supply switch sometimes the Link LED restarts. This is not frequent but unusual.Our device runs on both AC and rechargeable battery power. Every-time when continuously I turn ON and OFF the AC power for 5-10 times it occurs(Link LED restarts) once. When it is on battery power it also happens.(May be the link is getting disconnected and restarting) I have also checked the supply which doesn’t fluctuate at that moment(3.28V).I have done some experiment on this. Below are the observations of the experiment:During the restart of the link led, the fraction of seconds for the which the LINK LED turns OFF, the voltage level of the LINK LED pin of the Ethernet ic changes from 100 mv to 3.3V. After that, when it glows again it again come down to 100mv. In the whole process the, the voltage level at the reset pin of Ethernet ic is unchanged (2.8V).So,What could be the possible reasons for this issue? kindly assist for technical help regarding this topic.Thanks.

author: nctnico
author_rank: Super Contributor
timestamp: May 09, 2020, 05:01:03 pm
content: This is the wrong forum section so hopefully a moderator can move this thread.Your oscilloscope plots show no problem. Where is ETH_RESET coming from? What is the actual (measured) power supply voltage? The high level of ETH_RESET seems to be less than 3.3V.I'm also missing the 49.9 Ohm ethernet termination resistors in your schematic. This could cause erratic behaviour on the ethernet link because the signals are not terminated properly.

author: aakash dey
author_rank: Contributor
timestamp: May 11, 2020, 04:29:52 am
content: Hi,The ETH_RESET is connected to controller (ESP-32). The measured input voltage to the Ethernet IC is 3.32V. The ETH_RESET voltage is less than the input 3.3V. So, what could be the possible reason?I have connected an array of 4 49.9R resistors (R44) in the Ethernet transmission line. Please review it again. I hope my schematic is fine, Right?Thanks.

author: nctnico
author_rank: Super Contributor
timestamp: May 11, 2020, 09:49:59 pm
content: It looks OK. Still I would use seperate 49.9 Ohm resistors so you can route the ethernet traces as differential pairs. What does your board look like? If you didn't route the ethernet signals properly then that can also be a cause of your problems.The logic level of ETH_RESET looks OK. Did you try to trigger on edges on the ETH_RESET signal to make sure it stays inactive (high)?

author: aakash dey
author_rank: Contributor
timestamp: May 13, 2020, 06:34:32 am
content: Hi,Thanks for your reply. If you have any doubt regarding my design, Please find the design and Gerber files attached. I have two devices. In one of them I am using 49.9R array resistor and in other device I have used normal 49.9R resistor. But in both the cases I am facing the same issue.I haven't tried to trigger on edges on the ETH_RESET signal to make sure it stays inactive (high). Should I test by trying? If yes, Could you please explain how it could impact on my circuit?