AS4SD16M16 datasheet(18/51 Pages) AUSTIN

18 / 51 page

SDRAM

AS4SD16M16

Austin Semiconductor, Inc.

AS4SD16M16

Rev. 1.0 11/02

Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.

Fixed-length or full-page WRITE bursts can be truncated

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.

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 (t

) 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.

POWER-DOWN

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.

FIGURE 20: PRECHARGE Command

FIGURE 19: Terminating a WRITE

Burst

FIGURE 21: Power-Down

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