HYS64T32000HU-25F-B Datasheet, PDF (26/87 Pages) Qimonda AG – 240-Pin unbuffered DDR2 SDRAM Modules

Internet Data Sheet
HYS[64/72]T[32/64/128]xx0HU-[25F/2.5/3/3S/3.7/5]-B
Unbuffered DDR2 SDRAM Module
28) t_RPST end point and t_RPRE begin point are not referenced to a specific voltage level but specify when the device output is no longer driving
(t_RPST), or begins driving (t_RPRE). Figure 3 shows a method to calculate these points when the device is no longer driving (t_RPST), or begins
driving (t_RPRE) by measuring the signal at two different voltages. The actual voltage measurement points are not critical as long as the
calculation is consistent.
29) 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!).
30) 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!).
31) 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.
32) t_WTR is at lease two clocks (2 x t_CK) independent of operation frequency.
Rev. 1.3, 2006-12
26
03292006-6GMD-RSFT