is42s16128 Integrated Silicon Solution, Inc., is42s16128 Datasheet - Page 33

• Manufacturer Part Number: is42s16128
• Description: 128k Words Bits Banks Sdram
• Manufacturer: Integrated Silicon Solution, Inc.

Clock Suspend
When the CKE pin is dropped from HIGH to LOW during
a read or write cycle, the IS42S16128 enters clock sus-
pend mode on the next CLK rising edge. This command
reduces the device power dissipation by stopping the
device internal clock. Clock suspend mode continues as
long as the CKE pin remains low. In this state, all inputs
other than CKE pin are invalid and no other commands
can be executed. Also, the device internal states are
maintained. When the CKE pin goes from LOW to HIGH,
Integrated Silicon Solution, Inc. — 1-800-379-4774
Rev. A
03/13/00
IS42S16128
Bank Active Command Interval
When the selected bank is precharged, the period trp has
elapsed and the bank has entered the idle state, the bank
can be activated by executing the active command. If the
other bank is in the idle state at that time, the active
command can be executed for that bank after the period
t
active state. When a bank active command has been
RRD
CAS latency = 3
CAS latency = 2, burst length = 4
has elapsed. At that point both banks will be in the
COMMAND
COMMAND
COMMAND
CKE
CLK
CLK
CLK
I/O
BANK ACTIVE (BANK 0)
BANK ACTIVE (BANK 0)
READ (BANK 0)
READ 0
ACT 0
ACT 0
t
t
RRD
RCD
D
OUT
CLOCK SUSPEND
BANK ACTIVE (BANK 1)
BANK ACTIVE (BANK 0)
0
READ 0
clock suspend mode is terminated on the next CLK rising
edge and device operation resumes.
The next command cannot be executed until the recovery
period (tcka) has elapsed.
Since this command differs from the self-refresh command
described previously in that the refresh operation is not
performed automatically internally, the refresh operation
must be performed within the refresh period (tref). Thus the
maximum time that clock suspend mode can be held is just
under the refresh cycle time.
ACT 1
executed, a precharge command must be executed for
that bank within the ACT to PRE command period (t
max.). Also note that a precharge command cannot be
executed for an active bank before t
After a bank active command has been executed and the
trcd period has elapsed, read write (including auto-
precharge) commands can be executed for that bank.
D
OUT
1
D
OUT
2
D
OUT
3
RAS
(min.) has elapsed.
ISSI
RAS
33
®