W9751G6KB WINBOND [Winbond], W9751G6KB Datasheet - Page 49

• Manufacturer Part Number: W9751G6KB
• Description: 8M ? 4 BANKS ? 16 BIT DDR2 SDRAM
• Manufacturer: WINBOND [Winbond]

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
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
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
22. The clock frequency is allowed to change during Self Refresh mode or precharge power-down mode. In case of clock
23. For these parameters, the DDR2 SDRAM device is characterized and verified to support tnPARAM = RU{tPARAM /
24. tDAL [nCK] = WR [nCK] + tnRP [nCK] = WR + RU {tRP [pS] / tCK(avg) [pS] }, where WR is the value programmed in the
Logic levels
V
REF
power down exit timing. tXARDS is expected to be used for slow active power down exit timing.
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.
impedance. Both are measured from tAOFD, which 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.
frequency change during precharge power-down, a specific procedure is required as described in section 7.10.
tCK(avg)}, which is in clock cycles, assuming all input clock jitter specifications are satisfied.
mode register set and RU stands for round up.
DQS
DQS
levels
Figure 19
For DDR2-667/800: 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: 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.
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.
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].
–
Differential input waveform timing – tDS and tDH
t
t
DS(ref)
DS(base)
t
DH(base)
t
DH(ref)
t
t
DS(ref)
DS(base)
- 49 -
t
DH(base)
t
DH(ref)
Publication Release Date: Dec. 09, 2011
V
V
V
V
V
V
V
DDQ
IH(ac)
IH(dc)
REF(dc)
IL(dc)
IL(ac)
SS
W9751G6KB
max
max
min
min
Revision A01