ii
ii
i
PEMPEM
PEMPEM
PEM
2.4G2.4G
2.4G2.4G
2.4G
b SDRAM-DDRb SDRAM-DDR
b SDRAM-DDRb SDRAM-DDR
b SDRAM-DDR
AS4DDR32M72PBG
AS4DDR32M72PBG
Rev. 1.2 06/09
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
9
Austin Semiconductor, Inc.
NAME (FUNCTION) CS# RAS# CAS# WE#
DDR
DESELECT (NOP)(9) H XXXX
NO OPERATION (NOP) (9) L H H H X
ACTIVE (Select bank and activate row) (3) L L H H Bank/Row
READ (Select bank and column, and start READ burst) (4) L H L H Bank/Col
WRITE (Select bank and column, and start WRITE burst) (4) L H L L Bank/Col
BURST TERMINATE (8) L H H L X
PRECHARGE (Deactivate row in bank or banks) (5) L L H L Code
AUTO REFRESH or SELF REFRESH (Enter self refresh mode) (6,7) L L L H X
LOAD MODE REGISTER (2) LLLLOp-Code
TRUTH TABLE - DM OPERATION
NAME (FUNCTION) DM DQs
WRITE ENABLE (10) L Valid
WRITE INHIBIT (10) H X
TRUTH TABLE - COMMANDS (NOTE 1)
NOTES:
1. CKE is HIGH for all commands shown except SELF REFRESH.
2. A0-12 define the op-code to be written to the selected Mode Register.
BA0, BA1 select either the mode register (0, 0) or the extended mode
register (1, 0).
3. A0-12 provide row address, and BA0, BA1 provide bank address.
4. A0-8 provide column address; A10 HIGH enables the auto precharge
feature (non-persistent), while A10 LOW disables the auto precharge
feature; BA0, BA1 provide bank address.
5. A10 LOW: BA0, BA1 determine the bank being precharged. A10 HIGH:
All banks precharged and BA0, 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. Applies only to read bursts with auto precharge disabled; this command
is undefined (and should not be used) for READ bursts with auto
precharge enabled and for WRITE bursts.
9. DESELECT and NOP are functionally interchangeable.
10. Used to mask write data; provided coincident with the corresponding
data.
READ
The READ command is used to initiate a burst read
access to an active row. The value on the BA0, BA1 inputs
selects the bank, and the address provided on inputs A0-
9 selects the starting column location. The value on input
A10 determines whether or not AUTO PRECHARGE is
used. If AUTO PRECHARGE is selected, the row being
accessed will be precharged at the end of the READ burst;
if AUTO PRECHARGE is not selected, the row will remain
open for subsequent accesses.
WRITE
The WRITE command is used to initiate a burst write
access to an active row. The value on the BA0, BA1 inputs
selects the bank, and the address provided on inputs A0-
9 selects the starting column location. The value on input
A10 determines whether or not AUTO PRECHARGE is
used. If AUTO PRECHARGE is selected, the row being
accessed will be precharged at the end of the WRITE
burst; if AUTO PRECHARGE is not selected, the row will
remain open for subsequent accesses. Input data
appearing on the D/Qs iswritten to the memory array
subject to the DQM input logic level appearing coincident
with the data. If a given DQM signal is registered LOW, the
corresponding data will be written to memory; if the DQM
signal is registered HIGH, the corresponding data inputs
will be ignored, and a WRITE will not be executed to that
byte/column location.
PRECHARGE
The PRECHARGE command is used to deactivate the open
row in a particular bank or the open row in all banks. The
bank(s) will be available for a subsequent row access a
specified time (tRP) after the PRECHARGE command is
issued. Except in the case of concurrent auto precharge,
where a READ or WRITE command to a different bank is
allowed as long as it does not interrupt the data transfer in
the current bank and does not violate any other timing
parameters. Input A10 determines whether one or all banks
are to be precharged, and in the case where only one bank
is to be precharged, inputs BA0, BA1 select the bank.
Otherwise BA0, BA1 are treated as “Don’t Care.” Once a
bank has been precharged, it is in the idle state and must
be activated prior to any READ or WRITE commands being
issued to that bank. A PRECHARGE command will be
treated as a NOP if there is no open row in that bank (idle
state), or if the previously open row is already in the process
of precharging.
