Hi Team,
customer follow this link to test and still have some questions.
https://www.ti.com/lit/an/snla371a/snla371a.pdf?ts=1623044709767&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDP83TG720S-Q1
(1) According to the method, the cable diagnostic test still has some problems. The short cable is no problem, but when the long cable (15m) is used, the PHY cannot detect any fault. Whether the remote end is open or short, the PHY It is detected that the termination is normal. Is there a limit to the length of the TDR measurement? Or is it caused by insufficient TDR measurement time setting?
(2) Does PHY chip, including this DP83TG720, have any requirements for the ripple or noise of the power supply? If the DC+AC is in the Recommended Operating Conditions, there is no problem, right?