64Mb: x32
SDRAM
Commands
Truth Table 1 provides a quick reference of avail-
able commands. This is followed by a written descrip-
tion of each command. Three additional Truth Tables
appear following the Operation section; these tables
provide current state/next state information.
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
NOTE:
1.
2.
3.
4.
CS# RAS# CAS# WE# DQM
H
L
L
L
L
L
L
L
L
–
–
X
H
L
H
H
H
L
L
L
–
–
X
H
H
L
L
H
H
L
L
–
–
X
H
H
H
L
L
L
H
L
–
–
X
X
X
L/H
8
L/H
8
X
X
X
X
L
H
ADDR
X
X
Bank/Row
Bank/Col
Bank/Col
X
Code
X
Op-Code
–
–
DQs
X
X
X
X
Valid
Active
X
X
X
Active
High-Z
5
6, 7
2
8
8
3
4
4
NOTES
5.
6.
7.
8.
CKE is HIGH for all commands shown except SELF REFRESH.
A0-A10 define the op-code written to the Mode Register.
A0-A10 provide row address, BA0 and BA1 determine which bank is made active.
A0-A7 provide column address; A10 HIGH enables the auto precharge feature (nonpersistent), while
A10 LOW disables the auto precharge feature; BA0 and BA1 determine which bank is being read from
or written to.
A10 LOW: BA0 and BA1 determine the bank being precharged. A10 HIGH: All banks precharged and
BA0 and BA1 are “Don’t Care.”
This command is AUTO REFRESH if CKE is HIGH; SELF REFRESH if CKE is LOW.
Internal refresh counter controls row addressing; all inputs and I/Os are “Don’t Care” except for CKE.
Activates or deactivates the DQs during WRITEs (zero-clock delay) and READs (two-clock delay). DQM0
controls DQ0-DQ7; DQM1 controls DQ8-DQ15; DQM2 controls DQ16-DQ23; and DQM3 controls
DQ24-DQ31.
64Mb: x32 SDRAM
64MSDRAMx32_5.p65 – Rev. B; Pub. 6/02
9
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©2002, Micron Technology, Inc.
MICRON [ MICRON TECHNOLOGY ]
