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HYB18L256169BF Datasheet, PDF (22/48 Pages) Qimonda AG – 256-Mbit Mobile-RAM
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HY[B/E]18L256169BF-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.
#, +
#OM MA ND 2% !$
!DDRE SS
"A!
#O LN
$1-
./ 0
./ 0
T$1 :
./ 0
./ 0
./ 0
./ 0
./ 0
$1
$/ N
$/ N  $/ N 
"A! #O LNBA NK! COLU MN N
$/ N $A TA/U TFRO MCOLU MNN
#, IN THECASESH OWN
$1 -READ LA TENCYT$1 :IS CLO CKCYCLE S
Figure 20 READ Burst - DQM Operation
$O NgT#A RE
2.4.5.4 READ to WRITE
A READ burst may be followed by or truncated with a WRITE command. The WRITE command can be performed
to the same or a different (active) bank. Care must be taken to avoid bus contention on the DQs; therefore it is
recommended that the DQs are held in High-Z state for a minimum of 1 clock cycle. This can be achieved by either
delaying the WRITE command, or suppressing the data-out from the READ by pulling DQM HIGH two clock cycles
prior to the WRITE command, as shown in Figure 21. With the registration of the WRITE command, DQM acts as
a write mask: when asserted HIGH, input data will be masked and no write will be performed.
#, +
#OM MA ND 2% !$
!DDRE SS
"A!
#O LN
$1-
$1
$1
./ 0
./ 0
./ 0
./ 0
72 )4%
"A!
#O LB
./ 0
./ 0
#, 
$/ N
#, 
$/ N 
$/ N
(IG H :
(IG H :
$)B
$)B  $)B 
$)B
$)B  $)B 
"A! #O LNBB ANK! COLU MN NB
$O NgT#A RE
$/N $ATA /UTFROMC OLU MNN$ )B$ ATA)NTOCOLU MNB
$1 -IS ASSERTED( )' (TOSET$1 STO(IG H : STA TEFORC LO CKCYC LE PRIO RTOTHE72)4% COMM AND 
Figure 21 READ to WRITE Timing
Data Sheet
22
Rev. 1.02, 2006-12
02032006-MP0M-7FQG
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