How critical are parameters like trace length matching, differential impedance, vias, etc. when designing a 10BASE-T only application? I know that due to the reduced frequency, there is a larger margin for error than for higher data rates, but there must be good-practice maximums and minimums.

For example, in a two-layer PCB that I am designing, I have the following parameters:

  • TX+ length: 25.946mm
  • TX- length: 26.764mm
  • RX+ length: 26.420mm
  • RX- length: 27.769mm
  • Differential impedance: 123ohm
  • Odd impedance: 61.7ohm

The 8P8C connector has integrated magnetics and the MAC/PHY is the ENC28J60. Sorry about the messy labels.

Sample 10BASE-T layout

  • 2
    \$\begingroup\$ That'll be fine. \$\endgroup\$ Commented Jul 31, 2017 at 16:51

1 Answer 1


10 Base-T runs at 10MHz, usually you don't need to worry about transmission line effects and impedance matching until 50MHz. It would be slightly better to keep traces short, and a ground plane underneath them if you can, this design looks ok.

  • \$\begingroup\$ Thanks. I will have a ground plane, but it's not shown in the picture. \$\endgroup\$ Commented Jul 31, 2017 at 19:35

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