HYS64T256020HU Datasheet, PDF (24/61 Pages) Qimonda AG – 240-Pin Unbuffered DDR2 SDRAM Modules

Internet Data Sheet
HYS[64/72]T256xxxHU–[3/…/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 t_JIT.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 t_JIT.PER.MIN = – 72 ps
and t_JIT.PER.MAX = + 93 ps, then t_{RPRE.MIN(DERATED)} = t_RPRE.MIN + t_JIT.PER.MIN = 0.9 x t_CK.AVG – 72 ps = + 2178 ps and t_{RPRE.MAX(DERATED)} = t_RPRE.MAX
+ t_JIT.PER.MAX = 1.1 x t_CK.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 t_JIT.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 t_JIT.DUTY.MIN = – 72 ps
and t_JIT.DUTY.MAX = + 93 ps, then t_{RPST.MIN(DERATED)} = t_RPST.MIN + t_JIT.DUTY.MIN = 0.4 x t_CK.AVG – 72 ps = + 928 ps and t_{RPST.MAX(DERATED)} = t_RPST.MAX
+ t_JIT.DUTY.MAX = 0.6 x t_CK.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 t_nPARAM = RU{t_PARAM / t_CK.AVG}, which is in clock
cycles, assuming all input clock jitter specifications are satisfied. For example, the device will support t_nRP = RU{t_RP / t_CK.AVG}, which is in
clock cycles, if all input clock jitter specifications are met. This means: For DDR2–667 5–5–5, of which t_RP = 15 ns, the device will support
t_nRP = RU{t_RP / t_CK.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{t_RP(ns) / t_CK(ns)}, where RU stands for round up. WR refers to the tWR parameter stored in the MRS. For t_RP, if the result
of the division is not already an integer, round up to the next highest integer. t_CK refers to the application clock period. Example: For
DDR2–533 at t_CK = 3.75 ns with t_WR programmed to 4 clocks. t_DAL = 4 + (15 ns / 3.75 ns) clocks = 4 + (4) clocks = 8 clocks.
30) t_DAL.nCK = WR [nCK] + t_nRP.nCK = WR + RU{t_RP [ps] / t_CK.AVG[ps] }, where WR is the value programmed in the EMR.
31) t_WTR is at lease two clocks (2 x t_CK) independent of operation frequency.
32) t_CKE.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 t_IS + 2 x t_CK + t_IH.
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 t_AOND.
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 t_AOFD.
35) When the device is operated with input clock jitter, this parameter needs to be derated by {–t_JIT.DUTY.MAX – t_{ERR(6-10PER).MAX}} and {–t_JIT.DUTY.MIN
– t_{ERR(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 t_{ERR(6-10PER).MIN} = – 272 ps, t_{ERR(6- 10PER).MAX} = + 293 ps, t_JIT.DUTY.MIN = – 106 ps and t_JIT.DUTY.MAX = + 94 ps,
then t_{AOF.MIN(DERATED)} = t_AOF.MIN + {– t_JIT.DUTY.MAX – t_{ERR(6-10PER).MAX}} = – 450 ps + {– 94 ps – 293 ps} = – 837 ps and t_{AOF.MAX(DERATED)} = t_AOF.MAX
+ {– t_JIT.DUTY.MIN – t_{ERR(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
tHZ
tRPST end point
VOH - x mV
VOH - 2x mV
VOL + 2x mV
VOL + x mV
T1 T2
tHZ,tRPST end point = 2*T1-T2
VTT + 2x mV
VTT + x mV
VTT - x mV
VTT - 2x mV
tLZ
tRPRE begin point
T1 T2
tLZ,tRPRE begin point = 2*T1-T2
Rev. 1.32, 2006-09
24
03062006-5RK8-1X8J