DP83867CR: Media Dependent Interface Polarity

Alan Hoehn

Part Number: DP83867CR

I am using the VQFN part in the RJ45 mirror mode and I am looking to verify the polarity of the signals. The datasheet is not completely clear to me for signals TD_P_A, TD_M_A, TD_P_B, TD_M_B, TD_P_C, TD_M_C, TD_P_D, TD_M_D.

Also, the RJ45 has integrated magnetics and it would aid layout if I could reverse the polarity on both the "B" and "D" pairs. Is this possible?

over 3 years ago

0 Geet Modi over 3 years ago

TI__Mastermind 26320 points

Hi,

In mirror mode, swap happens between pair A & D, pair B&C.

Regards,
Geet

0 Alan Hoehn over 3 years ago in reply to Geet Modi

Intellectual 460 points

I understand the swap. Is TD_P positive in regular mode and negative in mirror mode?

0 Geet Modi over 3 years ago in reply to Alan Hoehn

TI__Mastermind 26320 points

Hi Alan,

Yes, your understanding is correct.

Regards,
Geet

0 Alan Hoehn over 3 years ago in reply to Geet Modi

Intellectual 460 points

Thank you.

Does the part have any Automatic Detection and Correction of Pair Swaps, Pair Skew, and Pair Polarity?

0 Vikram Sharma over 3 years ago in reply to Alan Hoehn

TI__Genius 16025 points

Pair polarity can be "automatically" detected/corrected.

Same channel's transmitter and receiver connections can be automatically detected. (Auto MDI/MDIX)

Mirror function as explained above has to be done manually.

Regards,

Vikram

0 Alan Hoehn over 3 years ago in reply to Vikram Sharma

Intellectual 460 points

I am confused now. The "automatic" detection is only available if I am not in the mirror mode? When in mirror mode then there is no automatic detection?

0 Vikram Sharma over 3 years ago in reply to Alan Hoehn

TI__Genius 16025 points

Alan,

Automatic detection/correction of the pair polarity (negative swing instead of positive swing and vice-versa) and same channel's transmitter and receiver connections (mdi/Mdi-x) will be detected/corrected whether you are in normal mode or mirror mode.

Regards,

Vikram

Interface

Interface forum

DP83867CR: Media Dependent Interface Polarity