256Mb: x4, x8, x16 SDRAM
Commands
NO OPERATION (NOP)
The NO OPERATION (NOP) command is used to perform a NOP to the selected device
(CS# is LOW). This prevents unwanted commands from being registered during idle or
wait states. Operations already in progress are not affected.
LOAD MODE REGISTER (LMR)
The mode registers are loaded via inputs A[n:0] (where An is the most significant ad-
dress term), BA0, and BA1(see Mode Register (page 44)). The LOAD MODE REGISTER
command can only be issued when all banks are idle and a subsequent executable com-
mand cannot be issued until tMRD is met.
ACTIVE
The ACTIVE command is used to activate a row in a particular bank for a subsequent
access. The value on the BA0, BA1 inputs selects the bank, and the address provided se-
lects the row. This row remains active for accesses until a PRECHARGE command is is-
sued to that bank. A PRECHARGE command must be issued before opening a different
row in the same bank.
Figure 14: ACTIVE Command
CLK
CKE HIGH
CS#
RAS#
CAS#
WE#
Row address
Bank address
Address
BA0, BA1
Don’t Care
PDF: 09005aef8091e6d1
256Mb_sdr.pdf - Rev. R 10/12 EN
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© 1999 Micron Technology, Inc. All rights reserved.
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