Internet Data Sheet
HYS[64/72]T[32/64/128]xx0HU–[3/3S/3.7/5]–A
Unbuffered DDR2 SDRAM Modules
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) For these parameters, the DDR2 SDRAM device is characterized and verified to support tnPARAM = RU{tPARAM / tCK.AVG}, which is in clock
cycles, assuming all input clock jitter specifications are satisfied. For example, the device will support tnRP = RU{tRP / tCK.AVG}, which is in
clock cycles, if all input clock jitter specifications are met. This means: For DDR2–667 5–5–5, of which tRP = 15 ns, the device will support
tnRP = RU{tRP / tCK.AVG} = 5, i.e. as long as the input clock jitter specifications are met, Precharge command at Tm and Active command at
Tm + 5 is valid even if (Tm + 5 - Tm) is less than 15 ns due to input clock jitter.
29) 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.
30) tDAL.nCK = WR [nCK] + tnRP.nCK = WR + RU{tRP [ps] / tCK.AVG[ps] }, where WR is the value programmed in the EMR.
31) tWTR is at lease two clocks (2 x tCK) independent of operation frequency.
32) 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.
33) ODT turn on time min is when the device leaves high impedance and ODT resistance begins to turn on. ODT turn on time max is when
the ODT resistance is fully on. Both are measured from tAOND
34) ODT turn off time min is when the device starts to turn off ODT resistance. ODT turn off time max is when the bus is in high impedance.
Both are measured from tAOFD
.
.
35) 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. (Caution on the MIN/MAX usage!)
FIGURE 3
Method for calculating transitions and endpoint
VOH - x mV
VTT + 2x mV
VTT + x mV
VOH - 2x mV
tLZ
tHZ
tRPRE begin point
tRPST end point
VOL + 2x mV
VOL + x mV
VTT - x mV
VTT - 2x mV
T1 T2
tLZ,tRPRE begin point = 2*T1-T2
T1 T2
tHZ,tRPST end point = 2*T1-T2
Rev. 1.41, 2007-05
23
03292006-EZUJ-JY4S
QIMONDA [ QIMONDA AG ]
