HY[B/E]18L256160B[C/F]X-7.5
256-Mbit Mobile-RAM
Functional Description
2.4.5.3
READ - DQM Operation
DQM may be used to suppress read data and place the output buffers into High-Z state. The generic timing
parameters as listed in Table 10 also apply to this DQM operation. The read burst in progress is not affected and
will continue as programmed.
#,+
2%!$
./0
./0
./0
./0
./0
./0
./0
#OMMAN
RESS
"A !ꢏ
#OL N
!
T$1:
$1-
$1
$/ N
$/ Nꢔꢁ
$/ Nꢔꢆ
ꢒ $ONgT #ARE
"A !ꢏ #OL N ꢒ BANK !ꢏ COLUMN N
$/ N ꢒ $ATA /UT FROM COLUMN N
#, ꢒ ꢁ IN THE CASE SHOWNꢐ
$1- REA LATENCY T$1: IS ꢁ CLOCK CYCLES
Figure 20 READ Burst - DQM Operation
2.4.5.4
READ to WRITE
A READ burst may be followed by or truncated with a WRITE command. The WRITE command can be performed
to the same or a different (active) bank. Care must be taken to avoid bus contention on the DQs; therefore it is
recommended that the DQs are held in High-Z state for a minimum of 1 clock cycle. This can be achieved by either
delaying the WRITE command, or suppressing the data-out from the READ by pulling DQM HIGH two clock cycles
prior to the WRITE command, as shown in Figure 21. With the registration of the WRITE command, DQM acts as
a write mask: when asserted HIGH, input data will be masked and no write will be performed.
#,+
2%!$
./0
./0
./0
./0
72)4%
./0
./0
#OMMAN
RESS
"A !ꢏ
#OL N
"A !ꢏ
#OL B
!
$1-
#,ꢒꢁ
(IGHꢎ:
$/ N
$/ Nꢔꢀ
$) B
$) Bꢔꢀ
$) Bꢔꢁ
$1
$1
#,ꢒꢆ
(IGHꢎ:
$/ N
$) B
$) Bꢔꢀ
$) Bꢔꢁ
ꢒ $ONgT #ARE
"A !ꢏ #OL N ꢌBꢍ ꢒ BANK !ꢏ COLUMN N ꢌBꢍ
$/ N ꢒ $ATA /UT FROM COLUMN Nꢕ $) B ꢒ $ATA )N TO COLUMN Bꢕ
$1- IS ASSERTE ()'( TO SET $1S TO (IGHꢎ: STATE FOR ꢀ CLOCK CYCLE PRIOR TO THE 72)4% COMMAN ꢐ
Figure 21 READ to WRITE Timing
Data Sheet
22
Rev. 1.11, 2007-01
07142005-CR47-RB2E
QIMONDA [ QIMONDA AG ]
