K4T51043QE Datasheet, PDF (44/45 Pages) Samsung semiconductor – 512Mb E-die DDR2 SDRAM Specification

K4T51043QE
K4T51083QE
K4T51163QE
DDR2 SDRAM
36. These parameters are specified per their average values, however it is understood that the following relationship between the average timing and the
absolute instantaneous timing holds at all times. (Min and max of SPEC values are to be used for calculations in the table below.)
Parameter
Absolute clock Period
Absolute clock HIGH pulse width
Absolute clock LOW pulse width
Symbol
tCK(abs)
tCH(abs)
tCL(abs)
Min
tCK(avg),min + tJIT(per),min
tCH(avg),min x tCK(avg),min +
tJIT(duty),min
tCL(avg),min x tCK(avg),min +
tJIT(duty),min
Max
tCK(avg),max + tJIT(per),max
tCH(avg),max x tCK(avg),max +
tJIT(duty),max
tCL(avg),max x tCK(avg),max +
tJIT(duty),max
Units
ps
ps
ps
Example: For DDR2-667, tCH(abs),min = ( 0.48 x 3000 ps ) - 125 ps = 1315 ps
37. tHP is the minimum of the absolute half period of the actual input clock. tHP is an input parameter but not an input specification parameter. It is used
in conjunction with tQHS to derive the DRAM output timing tQH. The value to be used for tQH calculation is determined by the following equation;
tHP = Min ( tCH(abs), tCL(abs) ),
where,
tCH(abs) is the minimum of the actual instantaneous clock HIGH time;
tCL(abs) is the minimum of the actual instantaneous clock LOW time;
38. tQHS accounts for:
1) The pulse duration distortion of on-chip clock circuits, which represents how well the actual tHP at the input is transferred to the output; 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 independent of
each other, due to data pin skew, output pattern effects, and p-channel to n-channel variation of the output drivers
39. tQH = tHP - tQHS, where:
tHP is the minimum of the absolute half period of the actual input clock; and tQHS is the specification value under the max column.
{The less half-pulse width distortion present, the larger the tQH value is; and the larger the valid data eye will be.}
Examples:
1) If the system provides tHP of 1315 ps into a DDR2-667 SDRAM, the DRAM provides tQH of 975 ps minimum.
2) If the system provides tHP of 1420 ps into a DDR2-667 SDRAM, the DRAM provides tQH of 1080 ps minimum.
40. When the device is operated with input clock jitter, this parameter needs to be derated by the actual tERR(6-10per) of the input clock. (output derat-
ings are relative to the SDRAM input clock.)
For example, if the measured jitter into a DDR2-667 SDRAM has tERR(6-10per),min = - 272 ps and tERR(6-10per),max = + 293 ps, then
tDQSCK,min(derated) = tDQSCK,min - tERR(6-10per),max = - 400 ps - 293 ps = - 693 ps and tDQSCK,max(derated) = tDQSCK,max - tERR(6-
10per),min = 400 ps + 272 ps = + 672 ps. Similarly, tLZ(DQ) for DDR2-667 derates to tLZ(DQ),min(derated) = - 900 ps - 293 ps = - 1193 ps and
tLZ(DQ),max(derated) = 450 ps + 272 ps = + 722 ps.
41. When the device is operated with input clock jitter, this parameter needs to be derated by the actual tJIT(per) of the input clock. (output deratings are
relative to the SDRAM input clock.)
For example, if the measured jitter into a DDR2-667 SDRAM has tJIT(per),min = - 72 ps and tJIT(per),max = + 93 ps, then tRPRE,min(derated) =
tRPRE,min + tJIT(per),min = 0.9 x tCK(avg) - 72 ps = + 2178 ps and tRPRE,max(derated) = tRPRE,max + tJIT(per),max = 1.1 x tCK(avg) + 93 ps =
+ 2843 ps.
42. When the device is operated with input clock jitter, this parameter needs to be derated by the actual tJIT(duty) of the input clock. (output deratings are
relative to the SDRAM input clock.)
For example, if the measured jitter into a DDR2-667 SDRAM has tJIT(duty),min = - 72 ps and tJIT(duty),max = + 93 ps, then tRPST,min(derated) =
tRPST,min + tJIT(duty),min = 0.4 x tCK(avg) - 72 ps = + 928 ps and tRPST,max(derated) = tRPST,max + tJIT(duty),max = 0.6 x tCK(avg) + 93 ps = +
1592 ps.
43. When the device is operated with input clock jitter, this parameter needs to be derated by { - tJIT(duty),max - tERR(6-10per),max } and { -
tJIT(duty),min - tERR(6-10per),min } of the actual input clock. (output deratings are relative to the SDRAM input clock.)
For example, if the measured jitter into a DDR2-667 SDRAM has tERR(6-10per),min = - 272 ps, tERR(6- 10per),max = + 293 ps, tJIT(duty),min = -
106 ps and tJIT(duty),max = + 94 ps, then tAOF,min(derated) = tAOF,min + { - tJIT(duty),max - tERR(6-10per),max } = - 450 ps + { - 94 ps - 293 ps} =
- 837 ps and tAOF,max(derated) = tAOF,max + { - tJIT(duty),min - tERR(6-10per),min } = 1050 ps + { 106 ps + 272 ps } = + 1428 ps.
44 of 45
Rev. 1.8 July 2007