HI Chetan,
not sure why you want to measure output slew rates.
These are DRAM output parameters and the DRAM vendor needs to guarantee
them. So only if you do want to do the DRAM vendors job, or tell him his
devices is bad there is no reason to measure these.
You can not change them anyhow.
Most people would not even able to measure output slew rates and
Voh(DC), as you need a special testboard (ideal termination) and maybe
some Testmodes to measure (e. g. driving a DC 1 without having a DQ
input connected).
One bad thing is, that JEDEC changed the Vox(DC) spec .. this is not any
more a Level to be measured. This is a level to force to the DRAM to
measure currents for output driver linearity measurement. if you check
the high level with 1.1*VDDQ .. this is not easy to reach with a POD
driver unless you have bad overshoots ;-)
I have told this at least two vendors of Compliance apps some time ago
.. so maybe you can check for an update of your compliance app .. maybe
this is corrected in the meantime.
I guess the problem is the usual one:
The Compliance app claims to verify "READ" in your system. So far I have
seen no compliance app to do so. All just verify DRAM output parameters
(the DRAM vendors job).
Verifying System reads e. g. for adjusting Drivestrength and termination
in Read case is a difficult job, and you have to do this manually (maybe
you can fool the compliance app by deskewing the DQS).
Best regards
Hermann
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Am 20.06.2017 um 04:23 schrieb chetan reddy:
Hi all,
In the DDR4 measurements we are seeing failures in some of the parameters
like VOH, VOL, slew rate SRQdiffR and SRQseR.
Test setup: measurements are done at the memory side using interposer card
below the memory.
The compliance test suite shows the above errors, please kindly suggest
whether this is acceptable?
Regards
Chetan
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