determines whether BC4 (chop) or BL8 is used. After a READ command is issued, the
READ burst may not be interrupted.
Table 71: READ Command Summary
Function
Symbol
CKE
CS# RAS# CAS# WE#
BA
[3:0]
An
A12 A10
A[11,
9:0]
Prev.
Cycle
Next
Cycle
READ
BL8MRS,
BC4MRS
RD
H
L
H
L
H
BA
RFU
V
L
CA
BC4OTF
RDS4
H
L
H
L
H
BA
RFU
L
CA
BL8OTF
RDS8
H
L
H
L
H
BA
RFU
H
L
CA
READ with
auto
precharge
BL8MRS,
BC4MRS
RDAP
H
L
H
L
H
BA
RFU
V
H
CA
BC4OTF
RDAPS4
H
L
H
L
H
BA
RFU
L
H
CA
BL8OTF
RDAPS8
H
L
H
L
H
BA
RFU
H
CA
WRITE
The WRITE command is used to initiate a burst write access to an active row. The value
on the BA[2:0] inputs selects the bank. The value on input A10 determines whether or
not auto precharge is used. The value on input A12 (if enabled in the MR) when the
WRITE command is issued determines whether BC4 (chop) or BL8 is used.
Input data appearing on the DQ is written to the memory array subject to the DM input
logic level appearing coincident with the data. If a given DM signal is registered LOW,
the corresponding data will be written to memory. If the DM signal is registered HIGH,
the corresponding data inputs will be ignored and a WRITE will not be executed to that
byte/column location.
Table 72: WRITE Command Summary
Function
Symbol
CKE
CS# RAS# CAS# WE#
BA
[3:0]
An
A12 A10
A[11,
9:0]
Prev.
Cycle
Next
Cycle
WRITE
BL8MRS,
BC4MRS
WR
H
L
H
L
BA
RFU
V
L
CA
BC4OTF
WRS4
H
L
H
L
BA
RFU
L
CA
BL8OTF
WRS8
H
L
H
L
BA
RFU
H
L
CA
WRITE with
auto
precharge
BL8MRS,
BC4MRS
WRAP
H
L
H
L
BA
RFU
V
H
CA
BC4OTF
WRAPS4
H
L
H
L
BA
RFU
L
H
CA
BL8OTF
WRAPS8
H
L
H
L
BA
RFU
H
CA
PRECHARGE
The PRECHARGE command is used to deactivate the open row in a particular bank or
in all banks. The bank(s) are available for a subsequent row access a specified time (tRP)
after the PRECHARGE command is issued, except in the case of concurrent auto pre-
2Gb: x4, x8, x16 DDR3 SDRAM
Commands
PDF: 09005aef826aaadc
2Gb_DDR3_SDRAM.pdf – Rev. K 04/10 EN
116
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2006 Micron Technology, Inc. All rights reserved.