SN65DP141: DP141 eval board showing bad results with DP cables

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

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

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

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

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

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

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.

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

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

Jeff

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

Thanks

David

OK, will stand by

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

Jeff

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

Thanks

David

Sounds good, just need an address David

Jeff

No I did not

Jeff

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

David:

    Did we receive their system?

David:

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

Jeff

Jeff

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

Thanks

David

Thanks David. Let me know

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:

dp141_evm.pptx

Regards,

I.K. 

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

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. 

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. 

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

Thanks for the help.

Will stand by

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. 

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

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

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

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.