SDRAM
AS4SD2M32
Austin Semiconductor, Inc.
Fixed-length or full-page WRITE bursts can be truncated
POWER-DOWN
with the BURST TERMINATE command. When truncate a
WRITE burst, the input data applied coincident with the BURST
TERMINATE command will be ignored. The last data written
(provided that DQM is LOW at that time) will be the input data
applied one clock previous to the BURST TERMINATE
command. This is shown in Figure 19, where data n is the last
desired data element of a longer burst.
Power-down occurs if CKE is registered LOW coincident
with a NOP or COMMAND INHIBIT when no accesses are in
progress. If power-down occurs when all banks are idle, this
mode is referred to as precharge power-down; if power-down
occurs when there is a row active in any bank, this mode is
referred to as active power-down. Entering power-down
deactivates the input and output buffers, excluding CKE, for
maximum power saving while in standby. The device may not
remain in the power-down state longer then the refresh period
(64ms) since no refresh operations are performed in this mode.
The power-down state is exited by registering a NOP or
COMMAND INHIBIT and CKE HIGH at the desired clock edge
(meeting tCKS). See Figure 21.
PRECHARGE
The PRECHARGE command (see Figure 20) 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 some specified time (tRP) after the PRECHARGE
command is issued. 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.
When all banks are to be precharged, inputs 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.
FIGURE 20: PRECHARGE Command
FIGURE 19: Terminating a WRITE
Burst
A0-A9
FIGURE 21: Power-Down
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
AS4SD2M32
Rev. 1.0 1/08
18
AUSTIN [ AUSTIN SEMICONDUCTOR ]
