256MB / 512MB (x64)
168-PIN SDRAM DIMMs
Co m m a n d s
The Truth Table provides a quick reference of avail-
able commands. This is followed by written descrip-
tion of each com m and. For a m ore detailed descrip-
tion of commands and operations, refer to the 256Mb
SDRAM component data sheet.
Ta b le 9:
Tru t h Ta b le – SDRAM Co m m a n d s a n d DQMB Op e ra t io n
CKE is HIGH for all commands shown except SELF REFRESH; notes appear following the Truth Table
NAME (FUNCTION)
CS# RAS# CAS# WE# DQMB
ADDR
DQ
NOTES
H
L
L
L
L
X
H
L
X
H
H
L
X
H
H
H
L
X
X
X
X
X
COMMAND INHIBIT (NOP)
X
NO OPERATION (NOP)
X
Bank/Row
Bank/Col
Bank/Col
X
1
2
2
ACTIVE (Select bank and activate row)
READ (Select bank and column, and start READ burst)
H
H
L/H
L/H
X
L
Valid
WRITE (Select bank and column, and start WRITE
burst)
BURST TERMINATE
L
L
L
H
L
L
H
H
L
L
L
X
X
X
X
Code
X
Active
PRECHARGE (Deactivate row in bank or banks)
X
X
3
AUTO REFRESH or SELF REFRESH
(Enter self refresh mode)
H
4, 5
L
–
–
L
–
–
L
–
–
L
–
–
X
L
Op-code
X
6
7
7
LOAD MODE REGISTER
–
–
Active
High-Z
Write Enable/Output Enable
Write Inhibit/Output High-Z
H
NOTE:
1. A0–A12 provide row address; BA0–BA1 determine which device bank is made active.
2. A0–A9 provide column address; A10 HIGH enables the auto-precharge feature (nonpersistent), while A10 LOW dis-
ables the auto-precharge feature; BA0-BA1 determine which device bank is being read from or written to.
3. A10 LOW: BA0–BA1 determine which device bank is being precharged. A10 HIGH: all device banks are precharged
and BA0, BA1 are “Don’t Care.”
4. This command is AUTO REFRESH if CKE is HIGH, SELF REFRESH if CKE is LOW.
5. Internal refresh counter controls row addressing; all inputs and I/Os are “Don’t Care” except for CKE.
6. A0–A11 define the op-code written to the mode register and A12 should be driven LOW.
7. Activates or deactivates the DQs during WRITEs (zero-clock delay) and READs (two-clock delay).
32,64 Meg x 64 SDRAM DIMMs
SD8_16C32_64x64AG_C.fm - Rev. C 11/02
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©2002, Micron Technology Inc.
11
MICRON [ MICRON TECHNOLOGY ]
