Creating Ethernet Shield - Line Filters.

There are three line filters used on the Ethernet Shield... does anyone have any details on these? Part numbers or specs of the filter? Reference L1, L2, L3.


First sorry for my English.

I built one and not put them and runs perfectly.


Those are generally built in to the RJ45 connector. The combination is called a "magjack".

Check the datasheet on the WIZ chip for requirements.


L1, L2, L3

0805 surface mount ferrite beads.

Murata part number BLM21PG300

Available from digi-key, among others.

Manufacturer's Data Sheet:

The actual values of these components are not particularly critical, but are recommended to decrease noise interaction between digital and analog parts of the circuit.



Thanks for the reply guys... I've created a board based on the ethernet shield and I'm having a heck of a time getting it to work. I've soldered the W5100 chip using a bunch of techniques and all of them (5 boards / 5 W5100) have the same issue. Not sure if its the schematic that has a flaw or the values of components or a combination of both.

I think I'm using the exact parts that are on the arduino ethernet shield. However, there are a few parts that are different on the arduino ethernet shield than listed in the schematics for example:

  • The two tantalum capacitors listed as C19 and C20 are 10uf in the schematic but on the board they used 47uf -- which should they be?
  • They used 6.2k resistors on the board but in the schematics looks like it should be 12K and 12K @ 1% ohm? Other schematics show 12K & 300 ohm @ 1%. (R9,R10)
  • I'm using .1UF 16V X7R ceramic capacitors as the listed on the schematic as 100n (C3,C4,C5,C7,C12,C15,C16,C17,C18) -- I take it that is just fine.
  • I'm using 22pf CERAMIC Capacitors 50V NP0 for the (C13,C14)
  • A magjack SI-60062F just like the original board

I got my latest one to work for a brief a while (maybe 30 seconds) and then reset and stop working. I'm not sure where to begin troubleshooting. I've checked all boards and verified all traces and vias are working. There are no shorts, bridges, etc.

Any tips? How finicky is the W5100 chip?

Got a board working... I'll document how in a bit...