DP83867IR: TDx signals connection

wei ye

Part Number: DP83867IR
Other Parts Discussed in Thread: DP83822I

I know current drive type Ethernet PHY should connect the transformer center tap to VCC. But i see two different type connections with the TDx signals.

One is the TDx signals parallel connect to GND through resistor and capacitor, the other is the signal parallel connect to VCC through resistor.

Which one should i choose and why?

over 6 years ago

0 Ross Pimentel over 6 years ago

TI__Mastermind 23675 points

Hi,

The DP83867IR is a voltage mode line driver.
Termination is in series. Because of this the center taps should be connected to ground through a cap.
The center taps should be separated through their own caps.
Please see page #110 in the datasheet for the correct connection.

Kind regards,
Ross

0 wei ye over 6 years ago in reply to Ross Pimentel

Intellectual 280 points

Hi Ross,

Thank you for reminding me.

I have another question: If i choose a current mode PHY, which schematic is right?

Both of the design i have seen before in the reference design(data signal not pull up or pull up)

0 Ross Pimentel over 6 years ago in reply to wei ye

TI__Mastermind 23675 points

Hi,

For an example of a current mode line driver implementation, please see the DP83822I datasheet (page 88):
www.ti.com/.../dp83822if.pdf

Kind regards,
Ross

0 wei ye over 6 years ago in reply to Ross Pimentel

Intellectual 280 points

Hi,

Thank you very much. Now i know how to connect with both current mode and voltage mode PHY.

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DP83867IR: TDx signals connection