DP83822I: Help to pass compliance test (Duty Cycle Distortion)

user5339940

Prodigy 10 points

Part Number: DP83822I

Add test report and waveform data　(2021/3/19)

/cfs-file/__key/communityserver-discussions-components-files/138/Testreport_5F00_and_5F00_waveform.pdf

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Hello team,

Could you please help us to pass the ethernet compliance test with DP83822I?

Duty Cycle Distortion needs to be 500ps (± 250ps) or less, but it is about 600ps to 700ps on our design board.

The following is the measurement result.

-------------
T1:20.0ps
T2:400ps
T3:760ps ← Worst value
T4:420ps
T5:360ps
T6:340ps
---------------

1.Could you please help me to suggest resolution by changing register setting ?

2.Could you please help me to suggest resolution by changing peripheral components?

※The circuit diagram is stored in the TI internal link in the E2E thread linked below.
https://e2e.ti.com/support/interface/f/interface-forum/979184/dp83822i-help-to-pass-compliance-test-rise-and-fall-time

Regards

Suguro

over 4 years ago

0 Vikram Sharma over 4 years ago

TI__Genius 16030 points

Hello,

Can you please share the report and the register settings being used at present?

Regards,

Vikram

0 user5339940 over 4 years ago in reply to Vikram Sharma

Prodigy 10 points

Thank you for your reply.

After posting, I found the thread below.

https://e2e.ti.com/support/interface/f/interface-forum/343244/tlk105-register-setting-for-compliance-test-of-100base-duty-cycle-distortion-test

According to this, when Auto negosiation and Auto MDI were turned off and remeasurement was performed, the value of T3 decreased to 500 ps or less.

I passed the test, but the value is just barely enough, so I want to make it even better.

Shows the report and waveform.　(Attach the file to the thread)

What register value is required for register setting?

The parts that have changed in particular this time are as follows.

Addr	Value
0x0000	0x2100
0x0019	0x0421
0x0404	0x0024
0x0170	0x0e52

I'm curious that the waveform is on the spikes.

Is there any way to improve it?

Regards

Suguro

0 Vikram Sharma over 4 years ago in reply to user5339940

TI__Genius 16030 points

Hello,

Have you already tried the settings mentioned in the following app note for 100Base Tx compliance testing :

https://www.ti.com/lit/an/snla266/snla266.pdf?ts=1616604437599&ref_url=https%253A%252F%252Fwww.google.com%252F

Also I dont see the full report of all the test results and test setup. I could only find duty cycle test snapshots.

The spikes you mentioned can be because of resolution issue (which you may check by zooming in the smaller time window) or may be some supply/ground noise.

Regards,

Vikram

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DP83822I: Help to pass compliance test (Duty Cycle Distortion)