®
IS42S32200
ISSI
PRECHARGECommand
PRECHARGE
The PRECHARGE command (see figure) 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 deter-
mines 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.”
Onceabankhasbeenprecharged,itisintheidlestateand
must be activated prior to any READ or WRITE com-
mands being issued to that bank.
CLK
HIGH - Z
CKE
CS
RAS
CAS
WE
A0-A9
ALL BANKS
A10
POWER-DOWN
BANK SELECT
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 either
bank, this mode is referred to as active power-down.
Entering power-down deactivates the input and output
buffers, excluding CKE, for maximum power savings
while in standby. The device may not remain in the power-
down state longer than the refresh period (64ms) since no
refresh operations are performed in this mode.
BANK ADDRESS
BA0, BA1
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 below.
POWER-DOWN
CLK
tCKS
≥ tCKS
CKE
COMMAND
NOP
NOP
ACTIVE
t
t
t
RCD
RAS
RC
All banks idle
Input buffers gated off
Enter power-down mode
Exit power-down mode
DON'T CARE
Integrated Silicon Solution, Inc. — 1-800-379-4774
27
ADVANCE INFORMATION Rev. 00B
08/14/03
ISSI [ INTEGRATED SILICON SOLUTION, INC ]
