DP83867IR: DP83867IR

Hello,

We recommend you use the DP83869 instead of DP83867 for transformerless design.

We also encourage you to ensure that there are series decoupling on paths as well.

Are you looking for a 100M ethernet PHY or a 1G ethernet PHY? 

If you are operating at 100Mbps, the we recommend using the DP83822 or DP83826 for this speed and transformerless operation.

Kind Regards,

Joe

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Thank you Joe for replying to the email.  Please find the notes as mentioned below:

The requirement is to have a interface between two Ethernet devices on the same PCB as mentioned in the snla088 below:

The two Ethernet devices mentioned below, need to be interfaced on a single PCB without the RJ45 connector and magnetics.

Microchip KSZ9567R: 7-Port Gigabit Ethernet Switch with Two RGMII/MII/RMII Interfaces and Five Integrated Ethernet PHY.

TI Hercules TMS570LS3137: 32 Bit RISC Microcontroller having 10/100Mbps Ethernet MAC. 

 There should be a Ethernet PHY after the TI Hercules device.  TI DP83867 is chosen for this purpose. The proposed solution is as follows. Only two differential pairs are used considering the 100Mbps operation.

 I request your suggestion on the above design. 

 There was a suggestion from you regarding the usage of the DP83822.  But the device DP83822 has dedicated analog pins in transmit and receive directions respectively.  I request you to help us in understanding more.

Thank You.

Hi, 

I will look into your design and get back to you by the end of business tomorrow.

I will also provide more explanation on the DP83822 suggestion.

Kind Regards,

Joe

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hello,

As far as my recommendation for the DP83822, I have listed my reasons for this recommendation:

• This PHY is used for transformer-less operation
• Smaller footprint and reduced cost (If your desired speed is 100Mbps)

Here is an example from the Datasheet for register configurations for a transformer-less design. 

May I ask how your block diagram would change when using the DP83822?

Kind Regards,

Joe

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hello Joe, Thanks for message.

In the TI DP83822 chip, the pins are classified as Transmit output and Receive input in the MDI as below:

 TD_M, TD_P --> Transmit differential.

RD_M, RD_P --> Receive differential.

But in the other ICs, the pins are not defined as Input and output, they are differential as shown below:

TD_P_A , TD_M_A --> Differential Transmit and Receive Signals.

TD_P_B, TD_P_B --> Differential Transmit and Receive Signals. 

Hence, I am not sure as to how to interface between these two devices.  Kindly help me in this regard.

Hello Joe,  Can we discuss once over a call please.  Thank you.

Hello,

Before we schedule a call, I believe the following functions will make the DP83822 suitable for your design.

• Using the auto-MDIX feature
• Using the polarity swap function in 0x000B Control Register #3

Please let me know if you have any questions about these features.

Kind Regards,

Joe

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hello Joe,

I referred to the Ethernet switch once again, and in the 100M mode, it supports the Auto MDI-X/ MDI mode. Please find the details as mentioned below:

So, The Ethernet switch is supporting Tx+/- on TXRX5P/M_A and Rx+/- on TXRX5P/M_B lines in the MDI.

Now the possible solution with the DP83822 is as like below:

The above is without any transformer and without any RJ-45 connector.  Can you please check the above and share your feedback.

Thank you.

Hello,

I will look into this and get back to you with some information by the end of business tomorrow. I apologize for the delays.

Kind Regards,

Joe

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hello,

I would like to point you to this post about using the DP83822 for your type of application

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/572998/dp83822hf-transformerless-operation 

and this app note on transformer-less ethernet operation for the DP83848.

https://www.ti.com/lit/an/snla088a/snla088a.pdf 

I think both of these resources will help you.

Please let me know if you have any questions.

Kind Regards,

Joe

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hello Joe,

The DP83822 device has been used in the design.

Please see the following attachments of the interface between the Ethernet switch and DP83822 device.

The two pairs of differntial lines are interfaced between the DP83822 and the Ethernet Switch.  Please suggest whether the 22nF is enough. Thank you.

Hi Nagaraju,

Joe is out of the office until 8/11 so I will be taking over. We're looking into your question and will get back to you by Friday.

Thanks,

Lucas

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hi Nagaraju,

The series decoupling caps should be in the range of 33nF-100nF. You will also need to change register 0x404 for full MLT-3.

Thanks,

Lucas

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and it is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).

Kind Attn Lucas, Thanks for the support.  Currently the DP83822 device is not available at majority of distributors.  Can you please kindly suggest another alternative or a source of procuring the DP83822 device itself?  Thank you.

Hi Nagaraju,

I will look into your application and try to provide you with an answer to your question by the end of business Friday (8/20).

Kind Regards,

Joe

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hello Joe, Can you please suggest a device.  Thank you.

Kind regards Nagaraju