DP83867E: Schematics check

Hi Prema,

Please refer to this schematic checklist ("Pin wise Checklist" sheet):

https://www.ti.com/lit/zip/slvrbn1

If you are able to review and return this with your inputs, I can share more feedback here.

Thank you,

Evan

SLVRBN1A_SCH_Checklist 1.xlsx

Hi Evan

I have attached the checklist with our comments and the schematics.Please let us know your feedback here. 

ETHERNET_RGMII_CIRCUIT_08Nov2024.pdf

Please use this schematics for your review.

Hi Prema,

I will review and share feedback later today.

Thank you,

Evan

Hi Evan, can you confirm whether we can use crystal part# FA-20H 25.0000MF20X-K3 (25 MHz ±10ppm Crystal 10pF ESR=80 Ohms) with DP83867E ?

Hi Evan

We do not have the space for external magnetics and hence we choose an integrated magnetics connector. Also, we have procured this connector. 

Hence want to know if there are any major concerns. 

Hi Prema,

There are link stability concerns using magnetics with center taps shorted.

Please share any alternate models for integrated magnetics without center taps shorted so I may review.

Thank you,

Evan

Hi Evan, we are in the final stages of the design, any modifications at this point of time will impact our project timelines. So, we would like to avoid making changes unless there's a major functional issue in the design. Iam hereby attaching the schematic for your reference. Please review and let me know if there are any issues. dp83867e_phy_ckt_191124.pdf

Hi Vivek,

This discrete transformer & schematic connections look good to me.

I see MDC PU was removed and RX_CTRL strap resistors populated - this is correct as well.

Were there any other changes from previous schematic version that I should review?

Thank you,

Evan

Hi Evan, thanks a lot for your quick feedback. We had replaced obsolete Marvell PHY part# 88E1116R with DP83867E in the current revision and retained the transformer and 25Mhz crystal as they were already ordered. As we have deviated from the recommended 18pF, ESR=30ohms crystal part# ABM3-25.000MHZ-D2Y-T with 10pF ESR=80 Ohms, part# FA-20H 25.0000MF20X-K3 in our design, can you confirm that works in our circuit as well? As the recommended crystal part# ABM3-25.000MHZ-D2Y-T is much bigger than existing part# FA-20H 25.0000MF20X-K3, it called for significant layout changes to accommodate it, so we would like to avoid it unless its a showstopper.

Hi Vivek,

For this crystal circuit, please include a 0ohm resistor in series from XO to crystal, as datasheet recommends:

This series resistance, as well as the 27pF capacitors used, may need to be tuned to achieve a clean 25M +/- 50PPM input to PHY.

As the exact values will depend on the crystal model and layout constraints, I recommend reaching out to the crystal vendor for support here.

Thank you,

Evan