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I performed several 10Base-T testing with Teledyne Lecroy ENET QualiPHY test setup (9.2.0.3 build 277958 core version) of both a custom developed board with your DP83848YB and an evaluation board from an european microcontroller manufacturer, which use the DP83848CVV instead.
In all the tests I experienced the same failure in the "Template - Internal MAU" Normal and Inverted measurements, which refer to 802.3 14.3.1.2.1 requirements, with roughly the same ratio of 50% passing repetitions and the same entity of masks violation, in order of a few tens millivolts.
Are you aware of any limitation in the performance of those DP83848 parts w.r.t. these specifications, when operating at 10 Mbits?
In several past projects we successfully used the same devices at 100 mbits and we never found any issue in the qualification testing phase, with the same test instruments and setups (but taking in account that different tests are performed by QualiPHY for 100 Mbits standards).
Thanks in advance
Hi Devitt,
Thank you for getting in touch with us.
I'm not aware of any issues with Template marginality on DP83848 devices.
Can you please share the test results with us?
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Regards,
Gokul.
Hi Gokul,
thanks for your reply, here are the measurements for the custom made board (DP83848YB):
And these are the measurements for the mentioned eval board (DP83848CVV):
Hi Devitt,
Thanks for sharing the waveforms.
Can you please measure the VOD (Output differential voltage) of the transmitter without Twisted Pair Model?
I'm looking for the below parameter from the datasheet.
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Regards,
Gokul.
Dear Gokul, here is a measurement of the mentioned EVAL board, obtained with an active differential probe on the test fixture TF-ENET-T-B by Teledyne Lecroy, configured without TPM:
Is it right for your purposes?
Best regards,
Devitt
Hi Devitt,
The VOD looks okay. With this VOD, I expect the templates to pass.
Can you please let me know what is the data sequence used to capture the signal above?
Can you please share the schematic of your custom board?
I tried looking for the user guide of the fixture TF-ENET-T-B? Can you please share it incase you have it?
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Regards,
Gokul.
Hi Gokul,
this is the configuration used for the measurements (all the other registers are at default values):
Register Address 0x00 -> 0x0100
Register Address 0x1A -> 0x0845
Register Address 0x1B -> 0x0020 (EOP0 sequence)
Register Address 0x19 -> 0x0121
Here you can find the Lecroy QualiPHY user manual, which provides several info about the test board configuration and use: https://cdn.teledynelecroy.com/files/manuals/qualiphyenetmanual.pdf
In the meantime, I asked the dealer for possible TF-ENET-T-B calibration needings, but he confirms that only the Oscilloscope needs periodically maintenance, not the board itself.
Finally, below an extract of our schematic is shown:
Hi Devitt,
Can you please try the same test after depopulating the ESD cell on the differential pair?
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Regards,
Gokul.
Hi Devitt,
I guess you have already verified this, but I wanted to double check the following.
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Regards,
Gokul.
Hi Gokul,
the tests were performed according to "10Base-T DOV Mask and Voltage Test" configuration in the above linked LeCroy User Manual, which seems to provide TPM and 100 ohm.
I'd like to share with you also the TF-ENET-B instructions: https://cdn.teledynelecroy.com/files/manuals/tf-enet-b-instructions.pdf
As specificed there, the provided test cable is 6 inches length: just for reference, I tried also with longer CAT6 cables (1, 3 meters), just to verify possible Teledyne's cable severe malfuctions. In my opinions, the measurements with those longer cables are not extremely different with the reference ones.
Hi Devitt,
Right now, I'm out of ideas. Let me check with my team and get back to you.
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Regards,
Gokul.
Hi Devitt,
Can you please get hold of EVM on ti.com and do the same compliance? This will give us an indication if there is any setup issue which is causing the failure. The EVM design is tested for compliance and we can use this as golden device.
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Regards,
Gokul.