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Commands
Truth Tables
The following tables provide a quick reference of available DDR2 SDRAM commands,
including CKE power-down modes and bank-to-bank commands.
Table 36: Truth Table – DDR2 Commands
Notes: 1–3 apply to the entire table
Function
CKE
CS#
RAS# CAS# WE#
BA2–
BA0 An–A11 A10
A9–A0 Notes
Previous
Cycle
Current
Cycle
LOAD MODE
H
L
BA
OP code
REFRESH
H
L
H
X
SELF REFRESH entry
H
L
H
X
SELF REFRESH exit
L
H
X
L
H
Single bank
PRECHARGE
H
L
H
L
BA
X
L
X
All banks PRECHARGE
H
L
H
L
X
H
X
Bank ACTIVATE
H
L
H
BA
Row address
WRITE
H
L
H
L
BA
Column
address
L
Column
address
WRITE with auto
precharge
H
L
H
L
BA
Column
address
H
Column
address
READ
H
L
H
L
H
BA
Column
address
L
Column
address
READ with auto
precharge
H
L
H
L
H
BA
Column
address
H
Column
address
NO OPERATION
H
X
L
H
X
Device DESELECT
H
X
H
X
Power-down entry
H
L
H
X
L
H
Power-down exit
L
H
X
L
H
Notes: 1. All DDR2 SDRAM commands are defined by states of CS#, RAS#, CAS#, WE#, and CKE at
the rising edge of the clock.
2. The state of ODT does not affect the states described in this table. The ODT function is
3.
“X” means “H or L” (but a defined logic level) for valid IDD measurements.
4. BA2 is only applicable for densities
≥1Gb.
5. An n is the most significant address bit for a given density and configuration. Some larg-
er address bits may be “Don’t Care” during column addressing, depending on density
and configuration.
1Gb: x4, x8, x16 DDR2 SDRAM
Commands
PDF: 09005aef821ae8bf
1GbDDR2.pdf – Rev. S 10/09 EN
69
Micron Technology, Inc. reserves the right to change products or specifications without notice.
2004 Micron Technology, Inc. All rights reserved.