K4T51043QE Datasheet, PDF (45/45 Pages) Samsung semiconductor – 512Mb E-die DDR2 SDRAM Specification

K4T51043QE
K4T51083QE
K4T51163QE
DDR2 SDRAM
44. For tAOFD of DDR2-400/533, the 1/2 clock of tCK in the 2.5 x tCK assumes a tCH, input clock HIGH pulse width of 0.5 relative to tCK. tAOF,min and
tAOF,max should each be derated by the same amount as the actual amount of tCH offset present at the DRAM input with respect to 0.5.
For example, if an input clock has a worst case tCH of 0.45, the tAOF,min should be derated by subtracting 0.05 x tCK from it, whereas if an input clock
has a worst case tCH of 0.55, the tAOF,max should be derated by adding 0.05 x tCK to it. Therefore, we have;
tAOF,min(derated) = tAC,min - [0.5 - Min(0.5, tCH,min)] x tCK
tAOF,max(derated) = tAC,max + 0.6 + [Max(0.5, tCH,max) - 0.5] x tCK
or
tAOF,min(derated) = Min(tAC,min, tAC,min - [0.5 - tCH,min] x tCK)
tAOF,max(derated) = 0.6 + Max(tAC,max, tAC,max + [tCH,max - 0.5] x tCK)
where tCH,min and tCH,max are the minimum and maximum of tCH actually measured at the DRAM input balls.
45. For tAOFD of DDR2-667/800, the 1/2 clock of nCK in the 2.5 x nCK assumes a tCH(avg), average input clock HIGH pulse width of 0.5 relative to
tCK(avg). tAOF,min and tAOF,max should each be derated by the same amount as the actual amount of tCH(avg) offset present at the DRAM input
with respect to 0.5.
For example, if an input clock has a worst case tCH(avg) of 0.48, the tAOF,min should be derated by subtracting 0.02 x tCK(avg) from it, whereas if an
input clock has a worst case tCH(avg) of 0.52, the tAOF,max should be derated by adding 0.02 x tCK(avg) to it. Therefore, we have;
tAOF,min(derated) = tAC,min - [0.5 - Min(0.5, tCH(avg),min)] x tCK(avg)
tAOF,max(derated) = tAC,max + 0.6 + [Max(0.5, tCH(avg),max) - 0.5] x tCK(avg)
tAOF,min(derated) = Min(tAC,min, tAC,min - [0.5 - tCH(avg),min] x tCK(avg))
tAOF,max(derated) = 0.6 + Max(tAC,max, tAC,max + [tCH(avg),max - 0.5] x tCK(avg))
where tCH(avg),min and tCH(avg),max are the minimum and maximum of tCH(avg) actually measured at the DRAM input balls.
Note that these deratings are in addition to the tAOF derating per input clock jitter, i.e. tJIT(duty) and tERR(6-10per). However tAC values used in the
equations shown above are from the timing parameter table and are not derated. Thus the final derated values for tAOF are;
tAOF,min(derated_final) = tAOF,min(derated) + { - tJIT(duty),max - tERR(6-10per),max }
tAOF,max(derated_final) = tAOF,max(derated) + { - tJIT(duty),min - tERR(6-10per),min }
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Rev. 1.8 July 2007