Rev. 1.11 - UBiio

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Internet Data Sheet HY[B/I]18T256[40/80/16]0B[C/F](L) 256-Mbit Double-Data-Rate-Two SDRAM 33) 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!). 34) 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. 35) t WTR is at lease two clocks (2 x t CK ) independent of operation frequency. Rev. 1.11, 2007-07 52 11172006-LBIU-F1TN
Internet Data Sheet HY[B/I]18T256[40/80/16]0B[C/F](L) 256-Mbit Double-Data-Rate-Two SDRAM FIGURE 8 Method for calculating transitions and endpoint FIGURE 9 Differential input waveform timing - t DS and t DS FIGURE 10 Differential input waveform timing - t lS and t lH Rev. 1.11, 2007-07 53 11172006-LBIU-F1TN
Page 1 and 2: July 2007 HY[B/I]18T256400B[C/F](L)
Page 3 and 4: Internet Data Sheet HY[B/I]18T256[4
Page 21 and 22: Internet Data Sheet 3 Functional De
Page 43 and 44: Internet Data Sheet 7 Timing Charac
Page 51: Internet Data Sheet HY[B/I]18T256[4
Page 59 and 60: Internet Data Sheet 7.3 Jitter Defi
Page 63 and 64: Internet Data Sheet 8 Package Dimen
Page 65 and 66: Internet Data Sheet 9 Product Nomen
Page 71: Internet Data Sheet Edition 2007-07

Rev. 1.11 - UBiio

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