UPD488448FF-C71-45-DQ2 データシートの表示（PDF） - NEC => Renesas Technology

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UPD488448FF-C71-45-DQ2

128 M-bit Direct Rambus™ DRAM

NEC => Renesas Technology 

µPD488448 for Rev. P

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

tCRDELAY

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

bank is to be re-activated without being

precharged. Case CR5 is illegal because an

DQA7..0

DQB7..0

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.

Data Sheet M14837EJ3V0DS00

21

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