EBE11ED8AJWA
Notes: 1. For each of the terms above, if not already an integer, round to the next higher integer.
2. AL: Additive Latency.
3. MRS A12 bit defines which active power down exit timing to be applied.
4. The figures of Input Waveform Timing 1 and 2 are referenced from the input signal crossing at the
VIH(AC) level for a rising signal and VIL(AC) for a falling signal applied to the device under test.
5. The figures of Input Waveform Timing 1 and 2 are referenced from the input signal crossing at the
VIL(DC) level for a rising signal and VIH(DC) for a falling signal applied to the device under test.
CK
DQS
/CK
/DQS
tIS
tIH
tIS
tIH
tDS tDH
tDS tDH
VDDQ
VDDQ
VIH (AC)(min.)
VIH (DC)(min.)
VREF
VIH (AC)(min.)
VIH (DC)(min.)
VREF
VIL (DC)(max.)
VIL (AC)(max.)
VSS
VIL (DC)(max.)
VIL (AC)(max.)
VSS
Input Waveform Timing 1 (tDS, tDH)
Input Waveform Timing 2 (tIS, tIH)
6.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;
7. tQHS accounts for:
a. 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
b. 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.
8. 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:
a. If the system provides tHP of 1315ps into a DDR2-667 SDRAM, the DRAM provides tQH of 975ps
(min.)
b. If the system provides tHP of 1420ps into a DDR2-667 SDRAM, the DRAM provides tQH of 1080ps
(min.)
9. RU stands for round up. WR refers to the tWR parameter stored in the MRS.
10. 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. = −272ps and
tERR(6-10per) max. = +293ps, then tDQSCK min.(derated) = tDQSCK min. − tERR(6-10per) max. =
−400ps − 293ps = −693ps and tDQSCK max.(derated) = tDQSCK max. − tERR(6-10per) min. = 400ps +
272ps = +672ps. Similarly, tLZ(DQ) for DDR2-667 derates to tLZ(DQ) min.(derated) = −900ps − 293ps =
−1193ps and tLZ(DQ) max.(derated)= 450ps + 272ps = +722ps.
Data Sheet E1054E30 (Ver. 3.0)
19
ELPIDA [ ELPIDA MEMORY ]
