K4J55323QG Datasheet, PDF (39/53 Pages) Samsung semiconductor – 256Mbit GDDR3 SDRAM

K4J55323QG
256M GDDR3 SDRAM
7.9.4 PRECHARGE
The PRECHARGE command 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 A8 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 the bank.
/CK
CK
CKE
HIGH
/CS
7.9.5 POWER-DOWN (CKE NOT ACTIVE)
Unlike SDR SDRAMs,GDDR3(x32) SDRAM requires CKE to be active at all
times an access is in progress; from the issuing of a READ or WRITE command
until completion of the burst. For READs, a burst completion is defined when the
Read Postamble is satisfied; For WRITEs, a burst completion is defined BL/2
cycles after the Write Postamble is satisfied.
Power-down is entered when CKE is registered LOW. 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. For maximum power savings, the user has the option of dis-
abling the DLL prior to entering power-down. However, power-down duration is
limited by the refresh requirements of the device, so in most applications,the self-
refresh mode is preferred over the DLL-disabled power-down mode.
When in power-down, CKE LOW and a stable clock signal must be maintained at
the inputs of the GDDR3 SDRAM, while all other input signals are "Don’t Care"
except data terminator disable command.
The power-down state is synchronously exited when CKE is registered HIGH (in
conjunction with a NOP or DESELECT command). A valid executable command
may be applied tPDEX later.
/RAS
/CAS
/WE
A0-A7, A9-A11
ALL BANKS
A8
ONE BANK
BA0, BA1
BA
DON’T CARE
BA=Bank Address
(if A8 is LOW; otherwise "Don’t Care")
PRECHARGE Command
Power-Down
T0
T1
T2
Ta0
Ta1
Ta2
Ta7
/CK
CK
t_IS
CKE
t_IS
t_PDEX
COMMAND
VALID
No PEAD/WRITE
access in progress
NOP
* Enter power - down mode
NOP
NOP
VALID
Exit power - down mode
* Once the device enters the power down mode, it should be in NOP state at least for 10ns
39 of 53
Rev. 1.1 November 2005