Data Sheet M14837EJ3V0DS00

21

µµµµPD488448 for Rev. P

9. COL-to-ROW Packet Interaction

Figure 9-1 shows arbitrary packets on the COL

and ROW pins. They must be separated by an

command and address values in the packets.

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

Likewise, in case CR7, the COLC packet causes an automatic retire to take place, and the ROW packet contains a

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

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

Figure 13-1

CR7

retire

Note 1

Da

Ba

Ca1

PRER

== Da

== {Ba, Ba+1, Ba-1} x..x

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.

Figure 9-1 COL-to-ROW Packet Interaction- Timing

CTM/CFM

DQA7..0

DQB7..0

COL4

..COL0

ROW2

..ROW0

T

Transaction a: COPa

Transaction b: ROPb

a1= {Da,Ba,Ca1}

b0= {Db,Bb,Rb}

ROPb b0

COPa a1