W9751G8JB Datasheet, PDF (49/86 Pages) Winbond – 16M  4 BANKS  8 BIT DDR2 SDRAM

W9751G8JB
DQS
DQS
Logic levels
tDS(base) tDH(base)
tDS(base) tDH(base)
VREF levels
tDS(ref)
tDH(ref)
tDS(ref)
tDH(ref)
V_DDQ
V_IH(ac) min
V_IH(dc) min
V_REF(dc)
V_IL(dc) max
V_IL(ac) max
V_SS
Figure 19 – Differential input waveform timing – tDS and tDH
18. User can choose which active power down exit timing to use via MRS (bit 12). tXARD is expected to be used for fast active
power down exit timing. tXARDS is expected to be used for slow active power down exit timing.
19. AL = Additive Latency.
20. 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 measure from tAOND, which is interpreted differently per speed bin.
For DDR2-667/800/1066, tAOND is 2 clock cycles after the clock edge that registered a first ODT HIGH counting the actual
input clock edges.
21. 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.
For DDR2-667/800: This is interpreted differently per speed bin. If tCK(avg) = 3 nS is assumed, tAOFD is 1.5 nS (=
0.5 x 3 nS) after the second trailing clock edge counting from the clock edge that registered a first ODT LOW and by
counting the actual input clock edges.
For DDR2-1066: This is interpreted as 0.5 x tCK(avg) [nS] after the second trailing clock edge counting from the
clock edge that registered a first ODT LOW and by counting the actual input clock edges. tAOFD is 0.9375 [nS] (=
0.5 x 1.875 [nS]) after the second trailing clock edge counting from the clock edge that registered a first ODT LOW
and by counting the actual input clock edges.
22. The clock frequency is allowed to change during Self Refresh mode or precharge power-down mode. In case of clock
frequency change during precharge power-down, a specific procedure is required as described in section 7.10.
23. 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.
Examples:
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 = 15nS, 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 15nS due to input clock jitter. For DDR2-1066 7-7-7, of which tRP = 13.125
nS, the device will support tnRP = RU{tRP / tCK(avg)} = 7, i.e. as long as the input clock jitter specifications are met,
Precharge command at Tm and Active command at Tm+7 is valid even if (Tm+7 - Tm) is less than 13.125 nS due to
input clock jitter.
24. tDAL [nCK] = WR [nCK] + tnRP [nCK] = WR + RU {tRP [pS] / tCK(avg) [pS] }, where WR is the value programmed in the
mode register set and RU stands for round up.
Example:
For DDR2-1066 7-7-7 at tCK(avg) = 1.875 nS with WR programmed to 8 nCK, tDAL = 8 + RU{13.125 nS / 1.875
nS} [nCK] = 8 + 7 [nCK] = 15 [nCK].
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Publication Release Date: Oct. 12, 2010
Revision A01