EM63B165TS
EtronTech
T0
T1
T2
T3
T4
T5
T6
T7
T8
CLK
Burst
Stop
NOP
WRITE A
DIN A0
NOP
NOP
NOP
NOP
NOP
NOP
COMMAND
don’t care
DIN A1
DIN A2
DQ
Figure 17. Termination of a Burst Write Operation
(Burst Length = X)
11 Device Deselect command (CS# = "H")
The Device Deselect command disables the command decoder so that the RAS#, CAS#, WE#
and Address inputs are ignored, regardless of whether the CLK is enabled. This command is similar to
the No Operation command.
12 AutoRefresh command
(RAS# = "L", CAS# = "L", WE# = "H", CKE = "H", A0-A12 = Don't care)
The AutoRefresh command is used during normal operation of the SDRAM and is analogous to
CAS#-before-RAS# (CBR) Refresh in conventional DRAMs. This command is non-persistent, so it
must be issued each time a refresh is required. The addressing is generated by the internal refresh
controller. This makes the address bits a "don't care" during an AutoRefresh command. The internal
refresh counter increments automatically on every auto refresh cycle to all of the rows. The refresh
operation must be performed 8192 times within 64ms. The time required to complete the auto refresh
operation is specified by tRC(min.). To provide the AutoRefresh command, all banks need to be in the
idle state and the device must not be in power down mode (CKE is high in the previous cycle). This
command must be followed by NOPs until the auto refresh operation is completed. The precharge time
requirement, tRP(min), must be met before successive auto refresh operations are performed.
13 SelfRefresh Entry command
(RAS# = "L", CAS# = "L", WE# = "H", CKE = "L", A0-A12 = Don't care)
The SelfRefresh is another refresh mode available in the SDRAM. It is the preferred refresh mode
for data retention and low power operation. Once the SelfRefresh command is registered, all the inputs
to the SDRAM become "don't care" with the exception of CKE, which must remain LOW. The refresh
addressing and timing is internally generated to reduce power consumption. The SDRAM may remain
in SelfRefresh mode for an indefinite period. The SelfRefresh mode is exited by restarting the external
clock and then asserting HIGH on CKE (SelfRefresh Exit command).
14 SelfRefresh Exit command
This command is used to exit from the SelfRefresh mode. Once this command is registered, NOP
or Device Deselect commands must be issued for tXSR(min.) because time is required for the
completion of any bank currently being internally refreshed. If auto refresh cycles in bursts are
performed during normal operation, a burst of 8192 auto refresh cycles should be completed just prior
to entering and just after exiting the SelfRefresh mode.
15 Clock Suspend Mode Entry / PowerDown Mode Entry command (CKE = "L")
When the SDRAM is operating the burst cycle, the internal CLK is suspended (masked) from the
subsequent cycle by issuing this command (asserting CKE "LOW"). The device operation is held intact
while CLK is suspended. On the other hand, when all banks are in the idle state, this command
performs entry into the PowerDown mode. All input and output buffers (except the CKE buffer) are
turned off in the PowerDown mode. The device may not remain in the Clock Suspend or PowerDown
state longer than the refresh period (64ms) since the command does not perform any refresh
operations.
Rev. 2.0
16
Jun. /2016
ETRON [ ETRON TECHNOLOGY, INC. ]
