PD488588 Datasheet, PDF (20/79 Pages) Elpida Memory – 288M bits Direct Rambus DRAM

µPD488588
9. COL-to-ROW Packet Interaction
Figure 9-1 shows arbitrary packets on the COL
Figure 9-1 COL-to-ROW Packet Interaction- Timing
and ROW pins. They must be separated by an
interval tCRDELAY which depends upon the
command and address values in the packets.
Table 9-1 summarizes the tCRDELAY value for all
possible cases.
Cases CR1, CR2, CR3, and CR9 show no
T₀ T₁ T₂ T₃ T₄ T₅ T₆ T₇ T₈ T₉ T₁₀ T₁₁T₁₂T₁₃ T₁₄ T₁₅ T₁₆T₁₇ T₁₈ T₁₉ T
CTM/CFM
ROW2
..ROW0
ROPb b0
t_CRDELAY
interaction between the COL and ROW packets,
either because one of the commands is a NOP or
COL4
..COL0
COPa a1
because the packets are directed to different
devices or to non-adjacent banks.
Case CR4 is illegal because an already-activated
DQA8..0
DQB8..0
bank is to be re-activated without being
precharged. Case CR5 is illegal because an
Transaction a: COPa
Transaction b: ROPb
a1= {Da,Ba,Ca1}
b0= {Db,Bb,Rb}
adjacent bank can’t be activated or precharged
until bank Ba is precharged first.
In case CR6, the COLC packet contains a RD command, and the ROW packet contains a PRER command for the
same bank. The tRDP parameter specifies the required spacing.
Likewise, in case CR7, the COLC packet causes an automatic retire to take place, and the ROW packet contains a
PRER command for the same bank. The tRTP parameter specifies the required spacing.
Case CR8 is labeled “Hazardous” because a WR command should always be followed by an automatic retire before
a precharge is scheduled. Figure 15-3 shows an example of what can happen when the retire is not able to happen
before the precharge.
For the purposes of analyzing COL-to-ROW interactions, the PREC, WRA, and RDA commands of the COLC
packet are equivalent to the NOCOP, WR, and RD commands. These commands also cause a precharge operation
to take place. This precharge may converted to an equivalent PRER command on the ROW pins using the rules
summarized in Figure 12-2.
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, PDNR, and RLXR
commands are discussed in a later section.
Table 9-1 COL-to-ROW Packet Interaction - Rules
Case # COPa Da
Ba
Ca1 ROPb Db
Bb
Rb
tCRDELAY Example
CR1 NOCOP Da
Ba
Ca1
x..x
xxxxx xxxxx
x..x
0
CR2 RD/WR Da
Ba
Ca1 x..x
/= Da xxxxx
x..x
0
CR3 RD/WR Da
Ba
Ca1 x..x
== Da /= {Ba, Ba+1, Ba-1} x..x
0
CR4 RD/WR Da
Ba
Ca1 ACT == Da == {Ba}
x..x
Illegal
CR5 RD/WR Da
Ba
Ca1 ACT == Da == {Ba+1, Ba-1} x..x
Illegal
CR6 RD
Da
Ba
Ca1 PRER == Da == {Ba, Ba+1, Ba-1} x..x
tRDP
Figure 13-1
CR7
retire ^{Note 1} Da
Ba
Ca1 PRER == Da == {Ba, Ba+1, Ba-1} x..x
tRTP
Figure 14-1
CR8
WR ^{Note 2}
Da
Ba
Ca1 PRER == Da == {Ba, Ba+1, Ba-1} x..x
0
Figure 15-3
CR9 xxxx
Da
Ba
Ca1 NOROP xxxxx xxxxx
x..x
0
Notes 1. This is any command which permits the write buffer of device Da to retire (see Table 3-3). “Ba” is the bank
address in the write buffer.
2. This situation is hazardous because the write buffer will be left unretired while the targeted bank is
precharged. See Figure 15-3.
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Data Sheet E0039N30 (Ver. 3.0)