DP83848C: It can not pass EMC for jitter test

Gary Zeng

Intellectual 1900 points

Part Number: DP83848C

Hi team,

My customer is using DP83848C for Robot communication.

Now they can not pass EMC for jitter test.

Below is schematic

I think it should be relevant to clock. They use RMII mode. Clock is from MCU.

Q1: Is it usful to use discrete 50MHz OSC like LMK6CE050000?

Q2: Are there any work-around solution can improve jitter performance?

3 months ago

0 Gerome Cacho 3 months ago

TI__Mastermind 43265 points

Hello,

For 100M PMA, jitter issues are typically indicative of a dirty reference clock. This would need to be checked and verified by ensuring PHY clock requirements are met.

While marginal PMA issues are observed, is there an issue with functionality? Have you tested packet errors? We have seen marginal PMA systems have no issue with communication.

Sincerely,

Gerome

0 Gary Zeng 3 months ago in reply to Gerome Cacho

TI__Intellectual 1900 points

Hi Cacho,

For data failure rate, I am still check with customer.

Customer want to add active OSC as bleow:

Q1: If VCC_3V3B pull-up is necessary here?

Q2: if there any risk for OSC's design?

0 Gerome Cacho 3 months ago in reply to Gary Zeng

TI__Mastermind 43265 points

Hello,

You will need to consult the oscillator team for this in a separate forum. This thread is dedicated to PHY support.

Sincerely,
Gerome

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DP83848C: It can not pass EMC for jitter test