MagJack Design Reference?

Thread Starter

Mark Hughes

Joined Jun 14, 2016
I'm putting a RJ45 magjack on a board for a project and neither the magjack datasheet nor the interface IC datasheets provide enough information for me to approach the problem with confidence. Can anyone recommend a resource or reference guide that describes best practices for connecting magjacks to ICs?

The current circuit is based on a design by the IC manufacturer WizNET for their W5500 IC.
I'm using a different RJ45 jack with integrated magnetics than the one shown in the design. The SI-51005-F by Belfuse

Some of the questions that I have:
1) The reference design uses a magnetic jack with separate centertaps, while the magjack used in my circuit has connected centertaps. What should be done with that net? Tie it to the 3V3 input with a 10 Ohm resistor as shown below? If so, shouldn't R6 & R7 be pulled up and decoupled?
2) How are the values of the damping resistors calculated (R21-R24)
3) Shouldn't R11 and R12 connect to 3V3 through PUR and then decoupled with the cap?
4) What if anything should be done about ESD?

I'm not looking for answers to these specific questions (although I wouldn't say no). I'm more interested in materials I can study. If you know of a resource, I'd appreciate it.
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