H5PS5162FFR-E3 Datasheet, PDF (37/39 Pages) Hynix Semiconductor – 512Mb DDR2 SDRAM

Release
H5PS5162FFR series
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 min-
imum.
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 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 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. (Caution on the min/max usage!)
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. (Caution
on the min/max usage!)
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. (Caution on the min/max usage!)
Rev. 1.0 / July. 2008
37