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)
CS# RAS# CAS# WE# DQM
ADDR
DQs NOTES
COMMAND INHIBIT (NOP)
H
L
L
L
L
L
L
L
X
H
L
X
H
H
L
X
H
H
H
L
X
X
X
X
X
X
X
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
Bank/Row
X
X
3
4
4
H
H
H
L
L/H8 Bank/Col
L/H8 Bank/Col
L
Valid
Active
X
H
H
L
L
X
X
X
X
Code
X
PRECHARGE (Deactivate row in bank or banks)
L
5
AUTO REFRESH or SELF REFRESH
(Enter self refresh mode)
L
H
X
6, 7
LOAD MODE REGISTER
L
–
L
–
–
L
–
–
L
–
–
X
L
Op-Code
X
2
8
8
Write Enable/Output Enable
Write Inhibit/Output High-Z
–
–
Active
High-Z
–
H
NOTE: 1. CKE is HIGH for all commands shown except SELF REFRESH.
2. A0-A10 define the op-code written to the Mode Register.
3. A0-A10 provide row address, BA0 and BA1 determine which bank is made active.
4. 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.
5. A10 LOW: BA0 and BA1 determine the bank being precharged. A10 HIGH: All banks precharged and
BA0 and 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). 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
MicronTechnology,Inc.,reservestherighttochangeproductsorspecificationswithoutnotice.
©2002,MicronTechnology,Inc.
9
MICRON [ MICRON TECHNOLOGY ]
