MT48LC64M4A2_03 Datasheet, PDF (15/61 Pages) Micron Technology – SYNCHRONOUS DRAM 256Mb: x4, x8, x16 SDRAM

Commands
Truth Table 1 provides a quick reference of
available commands. This is followed by a written de-
scription of each command. Three additional
256Mb: x4, x8, x16
SDRAM
Truth Tables appear following the Operation section;
these tables provide current state/next state
information.
Table 9: Truth Table 1 – Commands and DQM Operation
(Note: 1)
NAME (FUNCTION)
COMMAND INHIBIT (NOP)
NO OPERATION (NOP)
ACTIVE (Select bank and activate row)
READ (Select bank and column, and start READ burst)
WRITE (Select bank and column, and start WRITE burst)
BURST TERMINATE
PRECHARGE (Deactivate row in bank or banks)
AUTO REFRESH or SELF REFRESH
(Enter self refresh mode)
LOAD MODE REGISTER
Write Enable/Output Enable
Write Inhibit/Output High-Z
CS# RAS# CAS# WE# DQM ADDR DQs NOTES
HXXXX
X
X
L HHHX
X
X
L L H H X Bank/Row X
3
L H L H L/H⁸ Bank/Col X
4
L
H
L
L L/H⁸ Bank/Col Valid 4
L HH L X
X
Active
L
L
H
L
X
Code
X
5
L L LHX
X
X
6, 7
L L L L X Op-Code X
2
––––L
–
Active 8
– – – –H
–
High-Z 8
NOTE:
1. CKE is HIGH for all commands shown except SELF REFRESH.
2. A0-A11 define the op-code written to the mode register, and A12 should be driven LOW.
3. A0-A12 provide row address, and BA0, BA1 determine which bank is made active.
4. A0-A9, A11 (x4); A0-A9 (x8); or A0-A8 (x16) provide column address; A10 HIGH enables the auto precharge feature
(nonpersistent), while A10 LOW disables the auto precharge feature; BA0, BA1 determine which bank is being read from
or written to.
5. A10 LOW: BA0, BA1 determine the bank being precharged. A10 HIGH: All banks precharged and BA0, BA1 are “Don’t
Care.”
6. This command is AUTO REFRESH if CKE is HIGH, SELF REFRESH if CKE is LOW.
7. Internal refresh counter controls row addressing; all inputs and I/Os are “Don’t Care” except for CKE.
8. Activates or deactivates the DQs during WRITEs (zero-clock delay) and READs (two-clock delay).
PDF: 09005aef8091e6d1/Source: 09005aef8091e6a8
256MSDRAM.pmd – Rev. H; Pub. 2/05
15
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