DP83867ERGZ-R-EVM: Interfacing of "DP83867ERGZ" when using SGMII interface

Abhijit Pethkar41

Part Number: DP83867ERGZ-R-EVM
Other Parts Discussed in Thread: DP83867E

We are using "DP83867ERGZ" component in our design. We had some doubts while using SGMII interface in our design. The PHY is configured for 2.5V VDDIO.

It is mentioned in the datasheet that "The SGMII interface uses 1.25-Gbps LVDS differential signaling" and "The 1.25-Gbps rate of SGMII is excessive for 100-Mbps operation".

If I am configuring the SGMII interface for 1Gbps will the PHY operate in 1.25Gbps?
Can I still operate the PHY at lower speeds (software configurable) after I boot the PHY in 1Gbps?

over 5 years ago

0 Abhijit Pethkar41 over 5 years ago

Intellectual 280 points

The DC characteristics of the SGMII interface is not given in the datasheet. Can I interface the PHY with MAC whose receiver is given as given as below?

0 Ross Pimentel over 5 years ago in reply to Abhijit Pethkar41

TI__Mastermind 23675 points

Hi Abhijit,

SGMII supports 1Gbps, 100Mbps and 10Mbps speeds.
The DP83867E follows the SGMII specification and will be able to interface with the MAC.
Please be sure to have 0.1uF DC blocking caps on both the TX+/- and RX+/- paths.

0 Abhijit Pethkar41 over 5 years ago in reply to Ross Pimentel

Intellectual 280 points

Hi Ross,

Yes, I have connected series capacitors of 0.1uF to the Tx+/- and Rx+/- signals. During the perusing of the datasheet I found that the PHY works at 3 different IO voltages 1.8V, 2.5V and 3.3V. I would like to know how these three different supply voltages will affect the IO voltages of the SGMII interface. Whether the SGMII IO DC characteristics will get affected at these three supply voltages?

0 Ross Pimentel over 5 years ago in reply to Abhijit Pethkar41

TI__Mastermind 23675 points

SGMII is operated off our core supply and not VDDIO. The IO rail does not affect the SGMII characteristics.

Interface

Interface forum

DP83867ERGZ-R-EVM: Interfacing of "DP83867ERGZ" when using SGMII interface