WIZnet Developer Forum

Magnetics without RJ45 Jack to use with W5200

Hi – I am developing an embedded application which is very space constrained and since my Ethernet switch has tiny JST connectors I would like to have my W5200 without the (to me) huge RJ45 Jack and Plug – basically I want to put the W5200 and a separate transformer down with a small connector almost like the Wiz820io with magnetics but with a tiny JST instead of the RJ45. I looked through your website and I didn’t see any recommendations for an example magnetic transformer components from companies like Pulse or Bel. Is there an application note or some guidance somewhere that I missed?

Hugh Williams

The wiki [1] recommends following transformers for W5500:

  • H1102NL from Pulse
  • LCZ3A1CB from CETUS

Don’t know if this applies to W5200.

[1] wizwiki.net/wiki/doku.php?id=pro … fschematic

Did anyone ever get an answer to this? I am in the same boat at the moment

Hello everyone,
comparing the characteristics of potential transformers that can be used as described in the datasheet (W5500 in Chapter 5.5.5 and W5200 in Chapter 7.4.4) the two devices have the same characteristics on transformer side so what applies to the W5500 transformer scheme is applicable to the W5200 (same impedances, same transfer factors and same configuration diagram) without any changes and then applies.
What he said Zick and the link to the schema in previous post is correct.
You just have to try…

I have just had a board made with the reference design for W5500 with external magnetics.

I used the the ref schematic at wizwiki.net/wiki/lib/exe/fetch.p … 140808.pdf

As it came, I cant get the W5200 to get a link at all. It seems it doesn’t even attempt to establish the link.
I can however get a link at 10M if I reconfigure some components. I have removed C9 and 10 and replaced with a 0 ohm resistor. And I have also removed C15 and connected CT2 to CT1.

I know its not right, but in this configuration it seems to work, but it takes a little time to establish the link, and it is only ever at 10M where I need to get 100M.

I have noted the W5200 ref schematic pulls the TX and RX lines low, and the W5500 ref schematic pulls the TX lines high, and the RX lines low (with larger resistors here as well), is this correct, and which one should I be using?

Any help or insight will be appreciated.


Take a look here [url]PHY Connection and Led Error]

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