K4N26323AE Datasheet, PDF (26/52 Pages) Samsung semiconductor – 128Mbit GDDR2 SDRAM

K4N26323AE-GC
128M GDDR2 SDRAM
Power-Down
Power-down is entered when CKE is registered LOW (no accesses can be 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 CK, CK and CKE. During 4 cycles after power down mode issued, NOP should be issued or CS must be held
high. In Power Down mode, CKE Low and a stable clock signal must be maintained at the inputs of the GDDR2
SDRAM, and all other input signals are “Don’t Care” except first 4 cycles after power down mode issued. Power-down
duration is limited by the refresh requirements of the device.
The power-down state is synchronously exited when CKE is registered HIGH (along with a NOP or CS hold high). A
valid, executable command may be applied four clock cycles later.
Power Down
CK, CK
CKE
t_IS
t_IS
4tck
CMD
No column
access in
progress
VALID
NOP*1
NOP
NOP
NOP
NOP
NOP
VALID
Enter Power Down mode
( Read or Write operation
must not be in progress)
Exit
power down
mode
Don’t Care
*1. NOP or CS held high should be issued more than 4 cycles.
*CL + 2tCK after read or CL after last data in, a power-down command can be issued.
Burst Interruption
Interruption of a burst read or write cycle is prohibited.
No Operation Command
The No Operation Command should be used in cases when the GDDR2 SDRAM is in an idle or a wait state. The pur-
pose of the No Operation Command is to prevent the GDDR2 SDRAM from registering any unwanted commands
between operations. A No Operation Command is registered when CS is low with RAS, CAS, and WE held high at the
rising edge of the clock. A No Operation Command will not terminate a previous operation that is still executing, such as
a burst read or write cycle. The Deselect Command performs the same function as a No Operation Command. Deselect
Command occurs when CS is brought high at the rising edge of the clock, the RAS, CAS, and WE signals become don’t
cares.
- 26 -
Rev. 1.7 (Jan. 2003)