HY[B/E]18L256160B[C/F]X-7.5
256-Mbit Mobile-RAM
Functional Description
2.4.5.5
READ to PRECHARGE
A READ burst may be followed by, or truncated with a PRECHARGE command to the same bank, provided that
Auto Precharge was not activated. This is shown in Figure 22.
The PRECHARGE command should be issued x clock cycles before the clock edge at which the last desired data
element is valid, where x equals the CAS latency for READ bursts minus 1. Following the PRECHARGE
command, a subsequent ACTIVE command to the same bank cannot be issued until tRP is met. Please note that
part of the row precharge time is hidden during the access of the last data elements.
In the case of a READ being executed to completion, a PRECHARGE command issued at the optimum time (as
described above) provides the same operation that would result from the same READ burst with Auto Precharge
enabled. The disadvantage of the PRECHARGE command is that it requires that the command and address
busses be available at the appropriate time to issue the command. The advantage of the PRECHARGE command
is that it can be used to truncate bursts.
#,+
T20
2%!$
./0
./0
./0
02%
./0
./0
!#4
#OMMAN
RESS
"A !ꢏ
#OL N
"A !ꢏ
!
"A !
2OW A
0RE !LL
!0
!ꢀꢂ
ꢌ!0ꢍ
$IS !0
0RE "ANK !
#,ꢒꢆ
$/ N
$/ Nꢔꢀ
$/ Nꢔꢁ
$/ Nꢔꢆ
$1
ꢒ $ONgT #ARE
"A !ꢏ #OL N ꢒ BANK !ꢏ COLUMN Nꢕ "! !M 2OW ꢒ BANK !ꢏ ROW X
$/ N ꢒ $ATA /UT FROM COLUMN N
"URST ,ENGTH ꢒ ꢈ IN THE CASE SHOWNꢐ
#!3 LATENCY ꢒ ꢆ IN THE CASE SHOWN
ꢆ SUBSEQUENT ELEMENTS OF $ATA /UT ARE PROVI E IN THE PROGRAMME OR ER FOLLOWING $/ Nꢐ
Figure 22 READ to PRECHARGE Timing
Data Sheet
23
Rev. 1.11, 2007-01
07142005-CR47-RB2E
QIMONDA [ QIMONDA AG ]
