DP83848-EP: Compliance of the PHY rise/fall timings vs ANSI X3_263 1995

user4354969

Part Number: DP83848-EP

Hello,

We are using the DP 83848-EP PHYin an aerospaoce design.

By performing our worst case analysis, we realized that the 100BASE-TX Transmit timings (T2.8.1, min 2.6 ns max 5.5 ns) are not in line with the standard ANSI X3 263 1995 §9.1.6 Rise/fall time., which specifies min 3 ns and max 5 ns.

Is it a reason for this ?

Thank you in advance

Best regards,

PGC

unlocked 2/26/18[LE]

over 7 years ago

0 Wade Vonbergen over 7 years ago

TI__Guru 62930 points

PGC,
Let me research this and check with the commercial team and get back to you.
Regards,
Wade

0 Wade Vonbergen over 7 years ago in reply to Wade Vonbergen

TI__Guru 62930 points

PGC, I am still awaiting feedback from our test team. I should have information shortly.
Regards,
Wade

0 Wade Vonbergen over 7 years ago in reply to Wade Vonbergen

TI__Guru 62930 points

PGC,
Sorry for the long delay. There was some miscommunication on this end.

The reason for the relaxed specifications is to accommodate extended temperature range.

If this answers your question, please click "This Resolved My Question"
Regards,
Wade

0 user4354969 over 7 years ago in reply to Wade Vonbergen

Intellectual 370 points

Dear Wade,

Thank you for this answer.

However I don't understand the rationale, and therefore I will have issues to justify it in design reviews.

What is the point in having a wide temperature range if the standard are not meet inside it ? Does this mean that deriving a little from the ANSI is not identified as a issue according to TI experience ?

It would be appreciated if you could provide me with more rationale elements.

Best regards,

PGC

0 LeonardEllis over 7 years ago

TI__Guru 71526 points

2/26/18>[LE]Unlocked

0 Wade Vonbergen over 7 years ago in reply to LeonardEllis

TI__Guru 62930 points

PGC,
To answer your question it has become evident that the tie to the ANSI spec was not known during the characterization and setting of the limits for the temperature extension.

What is your required temperature range?

Regards,
Wade

0 user4354969 over 7 years ago in reply to Wade Vonbergen

Intellectual 370 points

Dear Wade,

Thank you for your answer.

Our maximum junction temperature would be 110°C, the minimum -20°C.

Best regards,

PGC

0 Wade Vonbergen over 7 years ago in reply to user4354969

TI__Guru 62930 points

PGC,
In your reduced temperature range, the device will comply with the ANSI specification. The relaxation was required to go from -40 down to -55.
There is some discussion that the test limits and specification can be tightened with some yield loss and still comply with the ANSI specification in full temp range of -55 to 125c.

If this answers your question, please click "Verify it as the answer"
Regards,
Wade

0 user4354969 over 7 years ago in reply to Wade Vonbergen

Intellectual 370 points

Dear Wade,

Ok, great if the timings are met for our temperature range.
Thanks for the support !

PGC

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DP83848-EP: Compliance of the PHY rise/fall timings vs ANSI X3_263 1995