Integrated Silicon Solution, Inc. — www.issi.com —
1-800-379-4774
29
Rev. 00D
06/02/08
IS42S32200E
CLK
CKE
HIGH - Z
ALL BANKS
BANK SELECT
BANK ADDRESS
CS
RAS
CAS
WE
A0-A9
A10
BA0, BA1
DON'T CARE
CLK
CKE
COMMAND
NOP NOP
ACTIVE
≥ t
CKStCKS
All banks idle
Enter
power-down mode
Exit power-down mode
tRCD
tRAS
tRC
Input buffers gated
off
PRECHARGE Command
POWER-DOWN
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 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.
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.
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 (t
RP) 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.”
Once a bank has been precharged, it is in the idle state and
must be activated prior to any READ or WRITE com-
mands being issued to that bank.
