SN75DP130: 8.1 Aux Channel Eye Test (Source) fail

AJ Cheng

Part Number: SN75DP130

Hello.

We used SN75DP130DS got compliance test fail on 8.1 Aux. Please kindly reference on below report and provide your suggestion. Thanks~

Fullscreen Aux_channel.html Download

<HTML><!--SkipSubstituteVars--><head><link id="ss1" href="Compact.css" rel="stylesheet" type="text/css" /><link id="sscommon" href="common.css" rel="stylesheet" type="text/css" /></head><BODY STYLE="background-color:white;font-family:Arial, helvetica, sans-serif; font-size:12pt"><a name="Top" /><DIV class="row"><span class="left"><img valign="top" src="agilent.gif" /></span><img valign="top" height="80" width="150" src="DisplayPort.GIF" /><center><DIV style="clear:both;line-height:1em;font-size:18pt;font-weight:bold;color:black">
            DisplayPort Test Report
            </DIV></center></DIV><br /><p style="margin:0.25em"><center><b>Overall Results:</b>1
of
                  3
       Tests Failed
               </center></p><center><TABLE class="TestConfigDetailsTable" BORDER="none" cellspacing="1pt"><tr><td colspan="2" style="background-color:#AAA;"><b><center>Test Configuration Details</center></b></td></tr><tr><td style="text-align:center;font-weight:bold;background-color:#7AE5F8" colspan="2">Device Description</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Test Specification</b></td><td>1.2b</td></tr><tr><td style="text-align:center;font-weight:bold;background-color:#7AE5F8" colspan="2">Test Session Details</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Fixture Type</b></td><td>Agilent W2641A</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Infiniium SW Version</b></td><td>04.60.0005</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Infiniium Model Number</b></td><td>DSOX93204A</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Infiniium Serial Number</b></td><td>MY51420112</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Application SW Version</b></td><td>3.31</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Debug Mode Used</b></td><td>No</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Probe (Channel 1)</b></td><td>Model: N2801A
Serial: US50071071
Head: N5444A
Atten: Calibrated (20 JUN 2014 14:29:43), Using Cal Atten (5.5387E+000)
Skew: Calibrated (20 JUN 2014 14:29:53), Using Cal Skew</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Probe (Channel 2)</b></td><td>Model: N2801A
Serial: US50071073
Head: N5444A
Atten: Calibrated (24 JUN 2014 14:02:42), Using Cal Atten (5.5717E+000)
Skew: Calibrated (24 JUN 2014 14:02:49), Using Cal Skew</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Probe (Channel 3)</b></td><td>Model: N2801A
Serial: US50071078
Head: N5444A
Atten: Calibrated (20 JUN 2014 14:32:40), Using Cal Atten (5.4408E+000)
Skew: Calibrated (20 JUN 2014 14:32:48), Using Cal Skew</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Probe (Channel 4)</b></td><td>Model: N2801A
Serial: US52392126
Head: N5444A
Atten: Calibrated (20 JUN 2014 14:33:33), Using Cal Atten (5.3792E+000)
Skew: Calibrated (20 JUN 2014 14:33:42), Using Cal Skew</td></tr><tr><td style="text-align:left;background-color:#AAA;"><b>Last Test Date</b></td><td>2014-06-25 17:59:33 UTC +08:00</td></tr></TABLE></center><h2 style="page-break-before:always">Summary of Results</h2><TABLE class="MarginThresholdsTable" BORDER="thin" cellspacing="0pt"><TR><TD colspan="2" class="header">Margin Thresholds</TD></TR><TR><TD class="warning">Warning</TD><TD>&lt;
                              2
%</TD></TR><TR><TD class="critical">Critical</TD><TD>&lt;
                              0
%</TD></TR></TABLE><br /><TABLE class="OverallSummaryTable" BORDER="thin" cellspacing="0pt"><TR><TD style="background-color:#AAA"><B>Pass</B></TD><TD style="background-color:#AAA"><B># Failed</B></TD><TD style="background-color:#AAA"><B># Trials</B></TD><TD style="background-color:#AAA"><B>Test Name</B></TD><TD style="background-color:#AAA"><B>Actual Value</B></TD><TD style="background-color:#AAA"><B>Margin</B></TD><TD style="background-color:#AAA"><B>Spec Range</B></TD></TR><a name="SummaryTest125002" /><TR class="odd"><TD class="passfail"><img src="&#xA;                    pass.gif&#xA;                  " /></TD><TD>0</TD><TD>1</TD><TD><a href="#Test125002">8.1 Aux Channel Peak to Peak Voltage Test (Source)</a></TD><TD>556.450000 mV</TD><TD class="good">91.9
%
               </TD><TD>VALUE &gt;= 290.000000 mV</TD></TR><a name="SummaryTest125000" /><TR class="even"><TD class="passfail"><img src="&#xA;                    pass.gif&#xA;                  " /></TD><TD>0</TD><TD>1</TD><TD><a href="#Test125000">Aux Channel Unit Interval Test (Source)</a></TD><TD>505.4493 ns</TD><TD class="good">47.3
%
               </TD><TD>400.0000 ns &lt;= VALUE &lt;= 600.0000 ns</TD></TR><a name="SummaryTest125001" /><TR class="odd"><TD class="passfail"><img src="&#xA;                    fail.gif&#xA;                  " /></TD><TD>1</TD><TD>1</TD><TD><a href="#Test125001">8.1 Aux Channel Eye Test (Source)</a></TD><TD>10.9640 k</TD><TD class="critical">-110E+04
%
               </TD><TD>-500 m &lt;= VALUE &lt;= 500 m</TD></TR></TABLE><br /><br style="page-break-before:always" /><h2> Report Detail</h2><br /><a name="Test125002" /><DIV class="TESTHEADER"><SPAN class="passfail"><img src="pass.gif" /></SPAN><SPAN class="testname">8.1 Aux Channel Peak to Peak Voltage Test (Source)</SPAN><SPAN class="SpecReference">
                    Reference:
            Display Port CTS</SPAN></DIV><SPAN class="TestDescription"><SPAN class="TestSummary"><span style="valign:top;padding-left:2pt;padding-right:2pt;background-color=black;color:white;">
                      Test Summary:
            </span><span class="Pass">Pass</span></SPAN><span><span style="margin-left:4px;valign:top;flow:left;padding-top:0px;padding-left:4px;padding-right:4px;text-decoration:underline;border-right: 1pt black solid">
                     Test Description:
            </span><span style="text-indent:2em;margin-left:6px;margin-right:4px"><nbsp />To evaluate the peak to peak voltage AUX Channel waveform for source.</span></span><br style="clear:both" /><SPAN class="FieldValueBlock"><span class="Field">Test Limits:</span><span class="Value">&gt;= 290.000000 mV</span></SPAN><SPAN class="FieldValueBlock"><span class="Field">Vpp (Source) </span><span class="Value">556.450000 mV</span></SPAN></SPAN><DIV style="clear:both" /><DIV class="ReferenceDivider"><span class="ReferenceDividerSpan">Result Details:</span></DIV><span style="font-size:10pt"><b>Result Details</b><br /></span><span class="FieldValueBlock"><span class="Field"><b>Source Aux Vpp Image</b></span><span class="Value">(See image)</span></span><DIV style="clear:both;"><span class="TableCaption">Trial 1</span></DIV><span style="ClearIfVerbose" /><span class="ImageTable"><div class="ImageCaption">Trial 1: Source Aux Vpp Image</div><div class="ImageTableRow"><span class="ImageTableCell"><IMG class="scopegrat" src="125002_1_1.png" /></span></div></span><br /><a name="Test125000" /><DIV class="TESTHEADER"><SPAN class="passfail"><img src="pass.gif" /></SPAN><SPAN class="testname">Aux Channel Unit Interval Test (Source)</SPAN><SPAN class="SpecReference">
                    Reference:
            Display Port CTS</SPAN></DIV><SPAN class="TestDescription"><SPAN class="TestSummary"><span style="valign:top;padding-left:2pt;padding-right:2pt;background-color=black;color:white;">
                      Test Summary:
            </span><span class="Pass">Pass</span></SPAN><span><span style="margin-left:4px;valign:top;flow:left;padding-top:0px;padding-left:4px;padding-right:4px;text-decoration:underline;border-right: 1pt black solid">
                     Test Description:
            </span><span style="text-indent:2em;margin-left:6px;margin-right:4px"><nbsp />To evaluate the unit interval of AUX channel.</span></span><br style="clear:both" /><SPAN class="FieldValueBlock"><span class="Field">Test Limits:</span><span class="Value">[400.0000 ns to 600.0000 ns]</span></SPAN><SPAN class="FieldValueBlock"><span class="Field">AUX Unit Interval </span><span class="Value">505.4493 ns</span></SPAN></SPAN><DIV style="clear:both" /><DIV class="ReferenceDivider"><span class="ReferenceDividerSpan">Result Details:</span></DIV><span style="font-size:10pt"><b>Result Details</b><br /></span><span class="FieldValueBlock"><span class="Field"><b>Source Aux Unit Interval</b></span><span class="Value">(See image)</span></span><span class="FieldValueBlock"><span class="Field"><b>Source Aux Unit Interval(Max)</b></span><span class="Value">503.3259000 ns</span></span><span class="FieldValueBlock"><span class="Field"><b>Source Aux Unit Interval(Min)</b></span><span class="Value">504.5027000 ns</span></span><DIV style="clear:both;"><span class="TableCaption">Trial 1</span></DIV><span style="ClearIfVerbose" /><span class="ImageTable"><div class="ImageCaption">Trial 1: Source Aux Unit Interval</div><div class="ImageTableRow"><span class="ImageTableCell"><IMG class="scopegrat" src="125000_1_1.png" /></span></div></span><br /><a name="Test125001" /><DIV class="TESTHEADER"><SPAN class="passfail"><img src="fail.gif" /></SPAN><SPAN class="testname">8.1 Aux Channel Eye Test (Source)</SPAN><SPAN class="SpecReference">
                    Reference:
            Display Port CTS</SPAN></DIV><SPAN class="TestDescription"><SPAN class="TestSummary"><span style="valign:top;padding-left:2pt;padding-right:2pt;background-color=black;color:white;">
                      Test Summary:
            </span><span class="Fail">FAIL</span></SPAN><span><span style="margin-left:4px;valign:top;flow:left;padding-top:0px;padding-left:4px;padding-right:4px;text-decoration:underline;border-right: 1pt black solid">
                     Test Description:
            </span><span style="text-indent:2em;margin-left:6px;margin-right:4px"><nbsp />To evaluate the AUX Channel waveform for source device ensuring that timing variables and amplitude trajectories support DisplayPort system objectives of Bit Error Rate in data transmission.</span></span><br style="clear:both" /><SPAN class="FieldValueBlock"><span class="Field">Test Limits:</span><span class="Value">[-500 m to 500 m]</span></SPAN><SPAN class="FieldValueBlock"><span class="Field">Eye Diagram Violation Points(Source) </span><span class="Value">10.9640 k</span></SPAN></SPAN><DIV style="clear:both" /><DIV class="ReferenceDivider"><span class="ReferenceDividerSpan">Result Details:</span></DIV><span style="font-size:10pt"><b>Result Details</b><br /></span><span class="FieldValueBlock"><span class="Field"><b>Source Aux Eye Image</b></span><span class="Value">(See image)</span></span><DIV style="clear:both;"><span class="TableCaption">Trial 1</span></DIV><span style="ClearIfVerbose" /><span class="ImageTable"><div class="ImageCaption">Trial 1: Source Aux Eye Image</div><div class="ImageTableRow"><span class="ImageTableCell"><IMG class="scopegrat" src="125001_1_1.png" /></span></div></span></BODY></HTML>

over 7 years ago

0 AJ Cheng over 7 years ago

Genius 3615 points

Hello.

Update information on below. Thanks~

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/138/Aux_5F00_channel.7z

0 Michael.Walker over 7 years ago in reply to AJ Cheng

TI__Mastermind 19720 points

Can you please post the schematic and layout for your design.

0 David (ASIC) Liu over 7 years ago in reply to Michael.Walker

TI__Guru**** 177301 points

AJ

When you measure AUX eye diagram, please make sure you have AC cap first, otherwise common mode voltage will be incorrect and you will lose half of the signal amplitude. Or you can use a high impedance probe without the AC cap for the measurement.

AUX --- Cap --- Scope

What is the common mode voltage on AUXP and AUXN?

Thanks
David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David and Michael.

Thanks for kindly help. Please reference schematic on below.

Can I change to test mode to solve this issue. Thanks~

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

Thanks for sending us the schematic. Looking at the schematic, do you have series resistors on AUX_SRCP/N changed to 0.1uF capacitors?

Per the DisplayPort CTS spec, the DUT shall be connected to a circuit equivalent to the respective counterpart of Figure 3-22 of the DP Standard. For example, if the DUT is a Source (transmitter), the test load shall be equivalent to the Sink (receiver) portion of Figure 3-22. This equivalent circuit shall include any loading of the test equipment.

So it looks you are doing a source application. In this case, you need to have the equivalent sink circuit (1M pullup/down plus AC coupling caps) in front of the scope to run the AUX compliance.

Thanks

David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.
Thanks for kindly help. We will try it. Any question will let you know. Thanks~

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.

Good day. We encountered the same problem after testing the SN75DP130 EVM. Please kindly reference on attached file.

On the EVM schematic the AUX_SRCP/N is 0.1uF. Do you have any other suggestions? Thanks for kindly help~

TI_EVM.zip

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

The DP130 EVM is placed in the diagram as shown in below

But you still need this circuit

You don't need the 50ohm termination and 1M pullup/pulldown is optional, but you need the 0.1uF cap in front of the scope. Since you are using SMA cable for the testing, you can just put two DC blocking caps in front of the N5444A probe head.

Thanks

David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.

Good day.

We changed R7901 / R7902 / R24 / R25 to 0.1uF then pass the test. Is this the correct solution? Thanks for kindly help.~

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

AJ

Thanks for the update, where does DDI_AUX+/- connected to?

David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David
DDI AUX will connect to DP monitor / TV. Thanks for kindly help~

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

Thanks, since you have the caps on R24 / R25, then you don't need the caps on R7901 / R7902.

David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.

In our SPEC and EVM schematic AUX Tx side are used 0 Ohm. Do we have any application note from TI can provide to customer. Thanks for kindly help~

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

AJ

Sorry, it is required to have AUXSRC side to be AC coupled (R7901/R7902) so we have the proper bias voltage. R24/R25 can still be zero ohm resistor.

Thanks
David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.

Good day. If R24/R25 use zero ohm resistor will get test fail. Only used 0.1uF on R24/R25 can pass it.

Do you have any suggestion for this problem? Thanks for kindly help~

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

When R24 and R25 are 0 ohm resistors, did you put 0.1uF blocking capacitor on the scope when doing the compliance test?

Having R24 and R25 to be 0.1uF is the same as putting the 0.1uF blocking capacitor on the scope. But the proper way is to have R24 and R25 to be zero ohm resistor and put the blocking capacitor on the scope.

Thanks

David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.

Good day.

About DP Compliance Test Hardware(DPR-100) is like on below photo. We can not add 0.1uF on test side.

Other DP solution are also no need add 0.1uF on test side. Do you have other suggestion If we don't use 0.1uF capacitor on R24/R25.

Thanks for kindly help~

R24/R25 : zero ohm

R24/R25 : 0.1uF capacitor

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

The first picture shows the setup for the compliance test of DP main link. Do you have a picture showing the AUX electrical testing setup?

Below is a picture shows the AUX testing setup from LeCroy. On the Wilder Tech Aux Controller board, you can tap into J3 and J4 jumper for the AUX testing.

Thanks

David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.

Good day.

Our Aux Controller board is old version. On J3/J4 just 2 pin for SDA/SCL and we also follow CTS test procedure.

I can't find add 0.1uF on J3/J4 relevant statement in the test specification.

Do you have any information about add 0.1uF on test equipment side? Thanks for kindly help.

CTS v1.2b test procedure

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

AJ

Are you using high impedance probe when doing the AUX channel test?

Thanks
David

0 Lee Jim7. over 7 years ago in reply to David (ASIC) Liu

Prodigy 10 points

Hi David,

It's ODM RD Jim, our SI team find out the TI re-driver AUX waveform issue as this topic of discussion.

Our Test Fixture you can refer the report.

0 David (ASIC) Liu over 7 years ago in reply to Lee Jim7.

TI__Guru**** 177301 points

Hi Jim, AJ

The LeCroy CTS spec assumes you are using the high impedance probe for the AUX channel measurement (please refer to section 6. Required Equipment for PHY CTS 1.2b Source Testing). The Keysight probe and head being used are differential probe.

The probe is has

DC input resistance : R diff = 100 kΩ ±2%, R se = 50 kΩ ±2%
Input resistance @ >10 kHz : R diff = 1 kΩ, R se = 500 Ω

If using high impedance probe, then the connection is correct as shown in the CTS spec.

If using differential probe, then you need to AC coupled the AUX lines. AJ has already demonstrated the AUX channel will pass the compliance if R24/25 have been changed to 0.1uF capacitors. Having R24/25 changed to 0.1.uF capacitors is ok for AUX compliance test, but this is not the proper way to implement DP130 AUX channel. The proper way to implement AUX and test AUX channel is DC couple AUX (R24 and R25 being 0 ohm resistors) and AC couple externally.

Thanks

David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.
Good day.
We will check probe on our side.
Do you have a EVM test report pass on AUX? Please kindly provide to us for reference about the report and equipment.
Thanks for kindly help~

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

AJ

Unfortunately, I don't have a compliance report on AUX . The AUX channel in DP130 is a mux with no signal conditioning. As long as the source AUX is compliant, and entire AUX channel is properly biased, then AUX will pass the compliance test.

Thanks
David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.

Good day.

We saw from the Intel PDG information that the output can be designed to series AC Cap 2. Can we follow to Intel's design? Thanks for kindly help~

0 David (ASIC) Liu over 7 years ago in reply to AJ Cheng

TI__Guru**** 177301 points

For our redriver, you need AC cap1 and AC cap 2 on both side of the redriver.

Thanks

David

0 AJ Cheng over 7 years ago in reply to David (ASIC) Liu

Genius 3615 points

Dear David.

I got it. Thanks for kindly help~

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SN75DP130: 8.1 Aux Channel Eye Test (Source) fail