DP83867IR: RJ45 and Magnetics

Sebastian Ciesluk80

Part Number: DP83867IR

Hi, In the DP83867 Troubleshooting Guide it is mentioned (no explicit mention of this in teh data sheet) that: "Each center tap of the magnetics should be independently de-coupled to ground via a 0.1uF capacitor." While it is quite easy to find RJ45 with magnetics having this option in big sizes ( I mean long 33mm) it is quite hard looking for shorter ones approx 22mm. There are RJ45s allowing for separate capacitors to center taps, however they also have all center taps shortened. Eg TE 1-2301994-2, link: www.digikey.co.uk/.../7516898 Could you please comment if such a jack is allowable and how the P1 should be connected? Thanks Sebastian

over 5 years ago

0 Geet Modi over 5 years ago

TI__Mastermind 26320 points

Hi,

For DP83867, we recomend each CT independently de-coupled to ground via capacitor. With all CT shorted together, device may have some IEEE compliance marginality.

Regards,
Geet

0 Sebastian Ciesluk80 over 5 years ago in reply to Geet Modi

Expert 1061 points

Thanks Geet,

I guess you talking also about the case i mentioned ie , each center tap is connected to cap and also shortened.

Are you able to comment how in case of the connector I mentioned (TE 1-2301994-2) I should connect the pin P1?

Thanks

Sebastian

0 Geet Modi over 5 years ago in reply to Sebastian Ciesluk80

TI__Mastermind 26320 points

Hi Sebastian,

DP83867 does not recomend shorting the CT.

For your specific question, you can try leaving P1 floating.

Regards,
Geet

0 Sebastian Ciesluk80 over 5 years ago in reply to Geet Modi

Expert 1061 points

Thank you very much Geet

Sebastian

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DP83867IR: RJ45 and Magnetics