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DS90UB954-Q1: Help with interpreting MAP results

Mitchell
Expert 4915 points
Part Number: DS90UB954-Q1


Hi Team,

My customer was having some stability issues across their system - a few channels on their board seemed to be unable to lock on default strobe. So, I had them do some testing with our MAP tool, and I could use some assistance on a couple items.

Here's their results from this initial testing:

Overall, there are good channels and a couple 'less good' channels in their system... For 'good channels' it is initially locked on the default value (strobe pos =7, eq = level 2). For 'less good channels' it will lock at strobe pos =9, eq = level 2. All channels are equipped with similar cable. By running the margin analysis test, we found some interesting results:

Attached is the example test result for 'less good' channel, you can see on strobe position 8, the available EQ window is narrower than strobe position 7. However, on good channels strobe position 8 usually has many more available eq levels. All 'less good' channels behave the same-- a narrow eq window on sp=8.

This leads us to a couple questions:

(1) Do you have any concerns regarding the test result? The shape of EQ/SP window is a little weird as strobe pos 8 should have a similar eq window compared with sp =7 or 9. Instead it is the opposite...

(2) There's some questioning on how exactly the adaptive search algorithm is working. From the datasheet it is using strobe position as outloop and eq level as inner loop. So theoretically if one position unlocked it should be starting searching from next EQ level? In their system search range is default so it searches from eq=2 and sp=7. For example if eq=2 sp=7 unlocked, it should check whether eq=3, sp=7 can lock. However, we never observed it locked at another eq level at sp=7 or any eq pos at sp =8. Instead it directly goes to eq=2 with sp =9.

Thanks,
Mitchell

  • 0
    TI__Guru** 109100 points

    Hello Mitchell,

    Is this measurement result from just one time testing or multiple times?

    Some times there is a resolution failure; the result on one box is directly on the edge of good but the algorithm display it as bad. Hence it is recommended in such cases to repeat the test.

    regarding the AEQ and SP settings, this can be changed in the registers. You can choose the SP to be outer and EQ inner loop or vice versa.

  • 0 in reply to Hamzeh Jaradat
    TI__Expert 4915 points

    Hi Hamzeh,

    It is from multiple times of testing. The procedure for the previous test is: manually set up strobe position and eq level -> wait for 1 seconds -> read fault ->after all positions recorded, repeat the whole procedure for 5 times -> the location is 'pass' if all 5 times 'pass' on this location.

    Thanks,
    Mitchell

  • 0 in reply to Mitchell
    TI__Guru** 109100 points

    Hello Mitchell,

    As I said, some times there is a resolution failure; the result on one box is directly on the edge of good but the algorithm display it as bad.

    You said, in your setup if in on location all 5 times are pass then this location is pass, so it looks like at that indicated location you have at least one time fail (not all 5 times fail)