Internet Data Sheet
HYS64T[32/64/128]xxxEDL–[25F/…/3.7](–)B2
Small Outlined DDR2 SDRAM Modules
18) 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.
19) 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 pchannel to n-channel variation
of the output drivers.
20) 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.
21) These parameters are measured from a data strobe signal ((L/U/R)DQS / DQS) crossing to its respective clock signal (CK / CK) crossing.
The spec values are not affected by the amount of clock jitter applied (i.e. tJIT.PER, tJIT.CC, etc.), as these are relative to the clock signal
crossing. That is, these parameters should be met whether clock jitter is present or not.
22) Input waveform timing is 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. See Figure 4.
23) These parameters are measured from a command/address signal (CKE, CS, RAS, CAS, WE, ODT, BA0, A0, A1, etc.) transition edge to
its respective clock signal (CK / CK) crossing. The spec values are not affected by the amount of clock jitter applied (i.e. tJIT.PER, tJIT.CC
,
etc.), as the setup and hold are relative to the clock signal crossing that latches the command/address. That is, these parameters should
be met whether clock jitter is present or not.
24) Input waveform timing is 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. See Figure 4.
25) tRPST end point and tRPRE begin point are not referenced to a specific voltage level but specify when the device output is no longer driving
(tRPST), or begins driving (tRPRE). Figure 2 shows a method to calculate these points when the device is no longer driving (tRPST), or begins
driving (tRPRE) by measuring the signal at two different voltages. The actual voltage measurement points are not critical as long as the
calculation is consistent.
26) 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!).
27) 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!).
28) DAL = WR + RU{tRP(ns) / tCK(ns)}, where RU stands for round up. WR refers to the tWR parameter stored in the MRS. For tRP, if the result
of the division is not already an integer, round up to the next highest integer. tCK refers to the application clock period. Example: For
DDR2–533 at tCK = 3.75 ns with tWR programmed to 4 clocks. tDAL = 4 + (15 ns / 3.75 ns) clocks = 4 + (4) clocks = 8 clocks.
29) tDAL.nCK = WR [nCK] + tnRP.nCK = WR + RU{tRP [ps] / tCK.AVG[ps] }, where WR is the value programmed in the EMR.
30) tWTR is at lease two clocks (2 x tCK) independent of operation frequency.
31) tCKE.MIN of 3 clocks means CKE must be registered on three consecutive positive clock edges. CKE must remain at the valid input level the
entire time it takes to achieve the 3 clocks of registration. Thus, after any CKE transition, CKE may not transition from its valid level during
the time period of tIS + 2 x tCK + tIH.
Rev. 1.1, 2007-01
22
08212006-PKYN-2H1B
QIMONDA [ QIMONDA AG ]
