Can PHY TX Output pair remain unconnected ? (TLK105)

jonds

Other Parts Discussed in Thread: TLK105In our application (Ethernet TAP) only the RX path of the PHY (TLK105) is required. The TX path is not needed. Can I leave the TD+- unconnected (in order to save some power) or is it really mandatory to terminate them? (and in the latter case, it is really needed to terminate them with 49r9?) Taking into consideration the MDIX mechanism where the TD pins might become inputs, some form of biassing the TD pins might be needed... Is the value of the RBIAS resistor still important in this RX only case (e.g. can 4k7 be used instead of 4k87?) Thanks, Jon

over 10 years ago

0 Ross Pimentel over 10 years ago

TI__Mastermind 23675 points

Hi Jon,

The RBIAS resistor must be 4.87Kohms in order to maintain proper chip operation. I will check with the design team about leaving the TD pins floating.

Regards,

Ross

0 Ross Pimentel over 10 years ago in reply to Ross Pimentel

TI__Mastermind 23675 points

Hi Jon,

There should be no issue with leaving the TD pins unconnected. You will need to make sure you have the correct MDI/MDIX at each link partner though and to also force the PHY into the desired rate and HD/FD mode since you will not be using auto-negotiate or auto-mdix.

Regards,

Ross

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Can PHY TX Output pair remain unconnected ? (TLK105)