Application Note | eDP Test Solution: Ensuring the Reliability of Panel Display Interfaces

eDP interface The test includes the physical layer test of source/sink . The source side selects the corresponding high-bandwidth oscilloscope for testing according to the device rate. The sink side test mainly performs the pressure tolerance test of the receiving end according to different rates .

According to the eDP physical layer electrical characteristics specification, the Source end physical layer test needs to complete the following test items:

eDP Source physical layer electrical characteristics test items

Different rates have different test item requirements, and each test item requires the testee to send a corresponding test pattern.

There are currently three manufacturers of high-bandwidth oscilloscopes in the market for eDP Source testing: Tektronix, Keysight, and LeCroy. According to the test standards, to meet the RBR and HBR rates, an oscilloscope with at least 8GHz bandwidth is required. To meet the HBR2 rate test, an oscilloscope with at least 12.5GHz bandwidth and a sampling rate of 80GS/s or more is required. If the HBR3 rate needs to be considered, the oscilloscope bandwidth needs to be considered 16GHz.

The test network connection is as follows:

Use a fixture to test network connectivity

Use the probe to test the network connection

The test requires three parts:

• High bandwidth and high sampling rate real-time oscilloscope that meets DUT rate requirements:

TEK DPO/MSO70000C/DX/SX Series Oscilloscope

• eDP Source port standard test fixture and high-speed differential probe:

• eDP conformance test software:

TEK eDP physical layer test software fully complies with the test specifications and can complete the various physical layer test items mentioned above.

Test plan:

Solution 1

During the test, the signal is introduced into the oscilloscope through a test fixture that matches the eDP Source DUT interface. The dedicated eDP physical layer software running on the oscilloscope will analyze the electrical indicators of each pair of lanes according to the indicators specified in the protocol, and finally determine whether the test results meet the consistency requirements.

TEK eDP physical layer test solution supports testing using eDP fixtures and differential SMA probes, or using differential probes to directly probe the eDP panel. Both methods can achieve simultaneous measurement of up to 4 lane pairs.

Solution 2

Use a fixture and SMA coaxial cable to directly introduce the signal from the DUT into the oscilloscope, which supports simultaneous measurement of up to 2 lane pairs.

If the EDP receiving end supports CTLE or CTLE+DFE equalization, eye diagram testing requires an oscilloscope that can simulate the eye diagram after CTLE or CTLE+DFE equalization. The TEK eDP physical layer test software itself supports CTLE simulation that meets the specification requirements, and DFE simulation can be achieved by using the TEK SDLA serial link analysis software.

SDLA Serial Link Analysis Software

Through the eDP test solution introduced in this article, we have discussed in detail how to use appropriate instruments and test methods to verify the physical layer performance of the eDP interface. Using Tektronix's high-bandwidth oscilloscope and dedicated test software can ensure the accuracy and consistency of the test results, thereby meeting the strict requirements of the eDP interface at different rates. Whether in the design stage or in the production process, using standardized test methods to verify the product is a key step to ensure product quality and performance. This not only helps to improve the market competitiveness of the product, but also effectively reduces potential quality risks.

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