Rev. 1.1 / Sep. 2009

24

H5DU2562GTR

H5DU2582GTR

20.tQH = tHP - tQHS, where:

tHP = minimum half clock period for any given cycle and is defined by clock high or clock low (tCH, tCL). tQHS accounts for 1) The

pulse duration distortion of on-chip clock circuits; and 2) The worst case push--out of DQS on one transition followed by the

worst case pull--in of DQ on the next transition, both of which are, separately, due to data pin skew and output pattern effects,

and p-channel to n-channel variation of the output drivers.

21. tDQSQ:

Consists of data pin skew and output pattern effects, and p-channel to n-channel variation of the output drivers for any given

cycle.

22. tDAL = (tWR/tCK) + (tRP/tCK)

For each of the terms above, if not already an integer, round to the next highest integer.

Example: For DDR266B at CL=2.5 and tCK=7.5 ns

tDAL = ((15 ns / 7.5 ns) + (20 ns / 7.5 ns)) clocks

= ((2) + (3)) clocks

= 5 clocks

23. In all circumstances, tXSNR can be satisfied using

tXSNR = tRFCmin + 1*tCK

24. The only time that the clock frequency is allowed to change is during self-refresh mode.

25. If refresh timing or tDS/tDH is violated, data corruption may occur and the data must be re-written with valid data before a valid

READ can be executed.