i.MX6UL DDR3L Calibration Values

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i.MX6UL DDR3L Calibration Values

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michaelperreca
Contributor II

Good Afternoon,

I recently received my first prototype boards which have the i.MX6UL and 512MB of DDR3L memory.

I'm run the DDR calibration using DDR Test Tool 2.6 with no issues. What I am seeing is variation in the calibration board to board.  Here are the values for all 16 boards:

Unit0x021b080c0x021b083c0x021b08480x021b0850
10x000000000x014C014C0x404042480x40405450
20x000000000x014801480x4040444A0x4040544E
30x000000000x014801480x4040424A0x4040544E
40x000000000x014401480x4040424A0x40405650
50x000000000x015401500x4040464E0x4040544E
60x000000000x014C01540x4040464A0x40405452
70x000000000x015001500x4040464A0x4040544E
80x000000000x014C014C0x4040444E0x4040544E
90x000000000x014C014C0x4040444C0x40405650
100x000000000x0150014C0x404046480x4040544C
110x000000000x014C01500x4040464C0x4040544E
120x000000000x014C01500x4040464C0x4040564E
130x000000000x015801540x4040464A0x4040564E
140x000000000x015401540x4040464E0x4040564E
150x000000000x014801400x404042440x4040524E
160x000000000x015001500x4040464C0x40405650

My questions are as follows:

1.  Why is there such variation between the boards?

2.  How should I go about selecting the proper value for production settings with these variations?

3.  There is obvious concerns over temperature that these settings are not proper, how should I account for temperature?

Thanks!

-Mike

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gusarambula
NXP TechSupport
NXP TechSupport

Hello Michael Perreca,

There may be small variations from board to board depending on factors such as the manufacturing process which leads to small variations. I would recommend taking a value in the middle of the range for each register and having an eye diagram on a sample of boards in order to see if the performance is the expected.

As for the variations on temperature these are accounted for in the ZQ calibration, which runs automatically at a periodic rate. You may find more information on this calibration on Application Note 4467 (link below) in section 7.2.

http://www.nxp.com/assets/documents/data/en/application-notes/AN4467.pdf

I hope this information helps!

Regards,

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