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SN65DP141: DP141 eval board showing bad results with DP cables

Jeffrey Boccaccio

Prodigy 225 points

Part Number: SN65DP141
Other Parts Discussed in Thread: TDP142

Customer request for DP 6ft @12Gbps. Found It's 141 solution and purchased DP141RLG Eval module.

Upon receiving the DP141 module we ran some basic DP cable tests with the device. The goal is to move 12Gbps over a 6 foot DP cable. However when using as little as 2ft its output was pathetic .In fact the cable by it self was just a little bit worse.

We must be doing something majorly wrong or the part cannot support DP over any longer cable length. At 12Gbps there is almost no eye at all.

The 4 wave form images show this with DP at 28AWG twin-ax.

As for Eval set up

Alll jumpers were set for:

Max EQ Settings Hi Hi

I2C mode Low

Cable/trace mode to Cable Hi

Gain set for high Hi

After these initial set ups we then changed them to many other configurations with the same or worse results.

Can you explain why this is happening? Is the part N/A to DP cable? The data sheet seems to claim this and the Eval comes equipped with DP connectors.

I have attached the Eye Patters to demonstrate what we measured. We sincerely hope we can achieve this with TI. The customer is very big and would love to use a domestic firm like TI.

Thank You

Jeffrey Boccaccio

InVisions Technology

over 5 years ago

0 Brian Zhou over 5 years ago

TI__Guru*** 129520 points

how do you connect board power? make sure J9 is connected to DP source and J10 to DP sink.

0 Jeffrey Boccaccio over 5 years ago in reply to Brian Zhou

Prodigy 225 points

Power is brought into micro usb 5 volts. Verified LP1 for 3.3 volts. J12 and j11 are undefined as for use. They are at default.

DP input J9 comes form Tek Pattern Generator, output J10 goes to Tek DSA. Both by way of DP fixtures.Since it is AC coupled no pull-ups were applied.

We use this same set up for HDMI and other CML without any issues.

Thank you for you prompt response

Jeffrey Boccaccio

0 David (ASIC) Liu over 5 years ago in reply to Jeffrey Boccaccio

TI__Guru**** 164981 points

Hi, Jeffrey

Do you have the insertion loss data for the 2ft and 12ft cable?

Would you please set EQ_MODE = L for cable mode, TX_DC_GAINS = L for 0 DC gain, DRV_PK# high to disable gain peaking, RX_GAIN high for 0dB, and sweep EQ0/1 setting?

Thanks

David

0 Jeffrey Boccaccio over 5 years ago in reply to David (ASIC) Liu

Prodigy 225 points

Thank you David for your response. I am sorry but I have been away all week. I believe I tried these but when I get in the office on Friday I will run it up again.

I do not have the insertion loss of these cables on hand. There is one 2 foot 28AWG and one 10 inch AWG.

I will try your suggestions and get back to you asap.

Thanks again

Jeff

0 Jeffrey Boccaccio over 5 years ago in reply to David (ASIC) Liu

Prodigy 225 points

Dave:

Thanks for the help. I do not have an SSD21 curve on these cables.

I did in fact set it all up the way you stated. I attached a pic of the board in its current configuration with EQ settings at High High.

Also I have attach 6Gbps Eye Patterns for each one EQ setting and one pic of the DUT with no eval board at all. Each pic is labeled to the TI code on the EQ.

You can see there is really no improvement at all.

This is used on about 12 inches of 28AWG Display port cable.

Not sure what else to do. Is the chip designed to hand cables? The data sheet does show a curve with a 12 foot cable.

Please let us know.

Jeff

0 David (ASIC) Liu over 5 years ago in reply to Jeffrey Boccaccio

TI__Guru**** 164981 points

Jeff

The connection looks to be correct. Would you please repeat the EQ experiment with VOD/CS (J3) pulled low?

Any chance you could ship the board + cable to me so I can take a look at them in the lab?

Thanks

David

0 Jeffrey Boccaccio over 5 years ago in reply to David (ASIC) Liu

Prodigy 225 points

Hey Dave:

Yes, I can do that. If you have the DP fixtures I can send you the cable to try.

I will have to get another one for you since today I cut it up to see if I can take one channel and bypass by fixture to be sure the loss in the fixture is to causing these issues.

If this does not work can you suggest another part that has the data rate and AC coupled with internal pull ups?

Thanks again Dave.

0 David (ASIC) Liu over 5 years ago in reply to Jeffrey Boccaccio

TI__Guru**** 164981 points

Jeff

I have the Wilder Tech DP test fixture, so it would be good if you can send me the cable and the EVM so I can see if this is an issue related to the EVM.

The other part I could recommend is TDP142: http://www.ti.com/lit/ds/sllsez1c/sllsez1c.pdf. It supports DP1.4 8.1G.

Thanks

David

0 Jeffrey Boccaccio over 5 years ago in reply to Jeffrey Boccaccio

Prodigy 225 points

Dave:

Just confirmed I will have my new DP cables in tomorrow. I will run them up one more time. If it still is not right I will send you the board and the cables.

Where do I send them to?

Thanks Dave

0 David (ASIC) Liu over 5 years ago in reply to Jeffrey Boccaccio

TI__Guru**** 164981 points

Jeff

Please accept my friendship request and I will send you the shipping address.

Thanks

David

0 Jeffrey Boccaccio over 5 years ago in reply to David (ASIC) Liu

Prodigy 225 points

OK, will stand by

0 Jeffrey Boccaccio over 5 years ago in reply to David (ASIC) Liu

Prodigy 225 points

I am sorry David but I do not understand what you mean by friendship request. Are you sending me another mail for confirmation?

Please explain. The cables have arrived we are ready to ship

Jeff

0 David (ASIC) Liu over 5 years ago in reply to Jeffrey Boccaccio

TI__Guru**** 164981 points

Jeff

Did you see an email from TI in your email inbox asking you to accept my friendship request?

Thanks

David

0 Jeffrey Boccaccio over 5 years ago in reply to David (ASIC) Liu

Prodigy 225 points

Sounds good, just need an address David

Jeff

0 Jeffrey Boccaccio over 5 years ago in reply to David (ASIC) Liu

Prodigy 225 points

No I did not

Jeff

0 David (ASIC) Liu over 5 years ago in reply to Jeffrey Boccaccio

TI__Guru**** 164981 points

Jeff

I just re-send you the invitation, would you please check? Or do you mind to share your email address in this thread?

Thanks

David

0 Brian Zhou over 5 years ago in reply to David (ASIC) Liu

TI__Guru*** 129520 points

David:

Did we receive their system?

0 Jeffrey Boccaccio over 5 years ago in reply to Brian Zhou

Prodigy 225 points

David:

Did you receive the board and cable yet. I have not heard anything

Jeff

0 David (ASIC) Liu over 5 years ago in reply to Jeffrey Boccaccio

TI__Guru**** 164981 points

Jeff

I received the package and will provide the measurement data this week.

Thanks

David

0 Jeffrey Boccaccio over 5 years ago in reply to David (ASIC) Liu

Prodigy 225 points

Thanks David. Let me know

0 Ikechukwu Anyiam over 5 years ago in reply to Jeffrey Boccaccio

TI__Mastermind 35130 points

Hi Jeff,

We looked at this in the lab but have not been able to recreate the issue with your cable. We even tried with an 18ft cable at 6Gbps, and the EVM was able to open the eye. You can find the results attached:

Regards,

I.K.

0 Jeffrey Boccaccio over 5 years ago in reply to Ikechukwu Anyiam

Prodigy 225 points

Thank you for the help. We are not sure why this looked so bad. Could you do us one more test at 12Gbps at at the same lengths and also a pic of the set up you are using. This would be a great help also.

Thanks again I.K.

Jeff

0 Ikechukwu Anyiam over 5 years ago in reply to Jeffrey Boccaccio

TI__Mastermind 35130 points

Hi Jeff,

Sure, here are the jumper settings:

We used a laptop as the source and a Keysight scope+software to generate the eye.

Doing a 12Gbps test will take some time to setup as the laptop only supports datarates up to 6Gbps, so we'll need to try and generate the data with a BERT. We will try to set this test up next week.

Regards,

I.K.

0 Ikechukwu Anyiam over 5 years ago in reply to Ikechukwu Anyiam

TI__Mastermind 35130 points

Hi Jeff,

Sorry for the delay. Some other items came up this week, but we haven't forgotten about this and are still working to set up the test.

Regards,

I.K.

0 Jeffrey Boccaccio over 5 years ago in reply to Ikechukwu Anyiam

Prodigy 225 points

Sounds like a plan. I will report into the customer and tell them what we are doing.

Thanks for the help.

Will stand by

0 Ikechukwu Anyiam over 5 years ago in reply to Jeffrey Boccaccio

TI__Mastermind 35130 points

Hi Jeff,

Sorry for the delay. Please find updated results for the 12Gbps test attached below:

5047.dp141_evm.pptx

The eye still looked better after passing through our EVM.

Regards,

I.K.

0 Jeffrey Boccaccio over 5 years ago in reply to Ikechukwu Anyiam

Prodigy 225 points

I K

Thank you so much for your help. These look good but they do not represent how 12G looks with longer cable like 12 feet or longer.

What can the device do over longer distances? This is what the account is looking for.They are looking for 28 and 30 AWG 6 to 7 meters. Is this doable?

If so then we will move forward with his board request.

Thanks again.

Jeff

0 David (ASIC) Liu over 5 years ago in reply to Jeffrey Boccaccio

TI__Guru**** 164981 points

Jeff

Do you know the approximate insertion loss of the 12 feet cable at 6GHz? The max equalizer DP141 at 6GHz is 15dB. If the cable insertion loss is less than 15dB, then DP141 RX should able to compensate. The second option is to cascade two DP141 and use both of them to compensate for long distance.

Thanks

David

0 Jeffrey Boccaccio over 5 years ago in reply to Jeffrey Boccaccio

Prodigy 225 points

I K

Thanks for the response. The customer wants us to go to board level and give it a shot.

Would you be so kind as to sending back the eval board to me.

please send to

Jeffrey Boccaccio

InVisions Technology

1230 North Highway US 1

Suite 30

Ormond Beach, Fl 32174

Thanks

Jeff

0 Ikechukwu Anyiam over 5 years ago in reply to Jeffrey Boccaccio

TI__Mastermind 35130 points

Hi Jeff,

Sure, but we'll also need your phone number for the shipment. You can send it to me at i-anyiam@ti.com.

Regards,

I.K.