K4R271669A Datasheet, PDF (17/64 Pages) Samsung semiconductor – 256K x 16/18 bit x 2*16 Dependent Banks Direct RDRAMTM

K4R271669A/K4R441869A
Direct RDRAM^™
COL-to-ROW Packet Interaction
T₀ T₁ T₂ T₃ T₄ T₅ T₆ T₇ T₈ T₉ T₁₀ T₁₁ T₁₂T₁₃ T₁₄ T₁₅ T₁₆T₁₇ T₁₈ T₁₉ T
CTM/CFM
ROW2
..ROW0
ROPb b0
t_CRDELAY
COL4
..COL0
COPa a1
DQA8..0
DQB8..0
Transaction a: COPa
Transaction b: ROPb
a1= {Da,Ba,Ca1}
b0= {Db,Bb,Rb}
Figure 9: COL-to-ROW Packet Interaction- Timing
Figure 9 shows arbitrary packets on the COL and ROW pins.
They must be separated by an interval t_CRDELAY which
depends upon the command and address values in the
packets. Table 13 summarizes the t_CRDELAY value for all
possible cases.
Cases CR1, CR2, CR3, and CR9 show no interaction
between the COL and ROW packets, either because one of
the commands is a NOP or because the packets are directed
to different devices or to non-adjacent banks.
Case CR4 is illegal because an already-activated bank is to
be re-activated without being precharged Case CR5 is illegal
because an 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 t_RDP parameter specifies the required spacing.
Likewise, in case CR7, the COLC packet causes an auto-
matic retire to take place, and the ROW packet contains a
PRER command for the same bank. The t_RTP 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 19 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 14.
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 inter-
action rules of the NAPR, PDNR, and RLXR commands are
discussed in a later section.
Table 13: COL-to-ROW Packet Interaction - Rules
Case # COPa Da Ba Ca1 ROPb ^Db
CR1 NOCOP Da Ba Ca1 x..x
xxxxx
CR2 RD/WR Da Ba Ca1 x..x
/= Da
CR3 RD/WR Da Ba Ca1 x..x
== Da
CR4 RD/WR Da Ba Ca1 ACT
== Da
CR5 RD/WR Da Ba Ca1 ACT
== Da
CR6 RD
CR7 retire^a
CR8 WR^b
Da Ba Ca1 PRER
Da Ba Ca1 PRER
Da Ba Ca1 PRER
== Da
== Da
== Da
CR9 xxxx
Da Ba Ca1 NOROP xxxxx
Bb
Rb
xxxx
x..x
xxxx
x..x
/= {Ba,Ba+1,Ba-1} x..x
== {Ba}
x..x
== {Ba+1,Ba-1} x..x
== {Ba,Ba+1,Ba-1} x..x
== {Ba,Ba+1,Ba-1} x..x
== {Ba,Ba+1,Ba-1} x..x
xxxx
x..x
t_CRDELAY
0
0
0
Illegal
Illegal
t_RDP
t_RTP
0
0
Example
Figure 15
Figure 16
Figure 19
a. This is any command which permits the write buffer of device Da to retire (see Table 8). “Ba” is the bank address in the write buffer.
b. This situation is hazardous because the write buffer will be left unretired while the targeted bank is precharged. See Figure 19.
Page 15
Rev. 1.02 Jan. 2000