SN75DP130: SN75DP130 EVM Test 3.3 Pre-Emphasis Failures

1859464

Part Number: SN75DP130

DisplayPort PHY Tx Compliance test 3.3 “Pre-Emphasis Level Verification and Maximum Pk-Pk Differential Voltage Testing (Normative)” was run on the TI SN75DP130 EVM. Failures were observed for 0 dB cases. Test 3.3 was initially run without terminations on unused lanes and then with terminations on unused lanes to see if results improved. Both sets of results have failures and are included. The second set also only tests with SSC disabled. Does the TI EVB pass test 3.3 ? If so, are there any special strap or I2C settings required to pass? See attached PDF. TI_E2E_Test-3.3_Draft_v0.pdf

over 7 years ago

0 Michael.Walker over 7 years ago

TI__Mastermind 19720 points

Hello,
We will try to duplicate this issue and get back to you with our results.

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

TI__Mastermind 19720 points

We were not able to replicate your results. We passed the compliance for the pre-emphasis. It might be because of your setup. We were using 4 inch SMA connectors and differential probes and you were using 12 in SMA connectors.

DisplayPort Device 1_Report_2018-07-25_02-02-36_UTC-0600.html.pdf

0 1859464 over 7 years ago in reply to Michael.Walker

Intellectual 575 points

Hi Michael,

Ok thanks for report. Just to confirm your other setup details so I can narrow down differences:

a. Was TI SN75DP130 EVM Setup: ADDR_EQ=Pull-Down, CAD_SNK=Pull-Down, NO I2C ?

b. Were unused lanes 50-ohm terminated or unterminated ?

c. What was host PC (and chip-set) and length of DisplayPort cable from host to EVB? For this test I would expect little/no dependencies on host and cable, but just want to match if I can.

I will try some short rigid SMA cables and other changes to see I can get closer to your results.

Regards,
KT

0 Michael.Walker over 7 years ago in reply to 1859464

TI__Mastermind 19720 points

a. The setup that I sent you was: ADDR_EQ=Mid, CAD_SNK=Pull-Down, NO I2C. I retested it at: ADDR_EQ=Pull-Down, CAD_SNK=Pull-Down, NO I2C and had the same result.

b. the unused lanes were terminated to 50-ohms.

c. The host PC was an old intel laptop. the cable was a 3m cable. these should not matter because it is a limiting redriver.

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SN75DP130: SN75DP130 EVM Test 3.3 Pre-Emphasis Failures