PD488588FF Datasheet, PDF (16/79 Pages) Elpida Memory – 288M bits Direct Rambus DRAM for High Performance Solution

µPD488588FF-C80-40
6. ROW-to-ROW Packet Interaction
Figure 6-1 shows two packets on the ROW pins separated by an interval tRRDELAY which depends upon the packet
contents. No other ROW packets are sent to banks {Ba, Ba+1, Ba-1} between packet “a” and packet “b” unless
noted otherwise.
Figure 6-1 ROW-to-ROW Packet Interaction - Timing
T₀ T₁ T₂ T₃ T₄ T₅ T₆ T₇ T₈ T₉ T₁₀ T₁₁T₁₂T₁₃ T₁₄ T₁₅ T₁₆T₁₇ T₁₈ T₁₉ T
CTM/CFM
ROW2
ROPa a0
..ROW0
ROPb b0
t_RRDELAY
COL4
..COL0
DQA8..0
DQB8..0
Transaction a: ROPa a0 = {Da,Ba,Ra}
Transaction b: ROPb b0= {Db,Bb,Rb}
Table 6-1 summarizes the tRRDELAY values for all possible cases.
Cases RR1 through RR4 show two successive ACT commands. In case RR1, there is no restriction since the ACT
commands are to different devices. In case RR2, the tRR restriction applies to the same device with non-adjacent
banks. Cases RR3 and RR4 are illegal (as shown) since bank Ba needs to be precharged. If a PRER to Ba, Ba+1,
or Ba-1 is inserted, tRRDELAY is tRC (tRAS to the PRER command, and tRP to the next ACT).
Cases RR5 through RR8 show an ACT command followed by a PRER command. In cases RR5 and RR6, there are
no restrictions since the commands are to different devices or to non-adjacent banks of the same device. In cases
RR7 and RR8, the tRAS restriction means the activated bank must wait before it can be precharged.
Cases RR9 through RR12 show a PRER command followed by an ACT command. In cases RR9 and RR10, there
are essentially no restrictions since the commands are to different devices or to non-adjacent banks of the same
device. RR10a and RR10b depend upon whether a bracketed bank (Ba+-1) is precharged or activated. In cases
RR11 and RR12, the same and adjacent banks must all wait tRP for the sense amp and bank to precharge before
being activated.
Cases RR13 through RR16 summarize the combinations of two successive PRER commands. In case RR13 there
is no restriction since two devices are addressed. In RR14, tPP applies, since the same device is addressed. In
RR15 and RR16, the same bank or an adjacent bank may be given repeated PRER commands with only the tPP
restriction.
Two adjacent banks can’t be activate simultaneously. A precharge command to one bank will thus affect the state of
the adjacent banks (and sense amps). If bank Ba is activate and a PRER is directed to Ba, then bank Ba will be
precharged along with sense amps Ba-1/Ba and Ba/Ba+1. If bank Ba+1 is activate and a PRER is directed to Ba,
then bank Ba+1 will be precharged along with sense amps Ba/Ba+1 and Ba+1/Ba+2. If bank Ba-1 is activate and a
PRER is directed to Ba, then bank Ba-1 will be precharged along with sense amps Ba/Ba-1 and Ba-1/Ba-2.
A ROW packet may contain commands other than ACT or PRER. The REFA and REFP commands are equivalent
to ACT and PRER for interaction analysis purposes. The interaction rules of the NAPR, NAPRC, PDNR, RLXR,
ATTN, TCAL, and TCEN commands are discussed in later section (see Table 3-2 for cross-ref).
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Data Sheet E0251N20 (Ver. 2.0)