EtronTech
EM638325
2Mega x 32 SDRAM
7
Write and AutoPrecharge command (refer to the following figure)
(RAS# = "H", CAS# = "L", WE# = "L", BS = Bank, A10 = "H", A0-A7 = Column Address)
The Write and AutoPrecharge command performs the precharge operation automatically after
the write operation. Once this command is given, any subsequent command can not occur within a
time delay of {(burst length -1) + tWR + tRP(min.)}. At full-page burst, only the write operation is
performed in this command and the auto precharge function is ignored.
T0
T 1
T2
T3
T4
T5
T6
T7
T8
CLK
Bank A
Write A
COMMAND
NOP
NOP
NOP
DIN A
DIN A
NOP
NOP
NOP
NOP
AutoPrecharge
Activate
tDAL
CAS# latency=2
DIN A
0
1
1
*
*
t
, DQ's
CK2
tDAL
CAS# latency=3
, DQ's
DIN A
0
t
CK3
Begin AutoPrecharge
Bank can be reactivated at completion of tDAL
tDAL= tWR + tRP
*
Burst Write with Auto-Precharge (Burst Length = 2, CAS# Latency = 2, 3)
8
Mode Register Set command
(RAS# = "L", CAS# = "L", WE# = "L", BS0,1 and A10-A0 = Register Data)
The mode register stores the data for controlling the various operating modes of SDRAM. The
Mode Register Set command programs the values of CAS# latency, Addressing Mode and Burst
Length in the Mode register to make SDRAM useful for a variety of different applications. The default
values of the Mode Register after power-up are undefined; therefore this command must be issued
at the power-up sequence. The state of pins BS0,1 and A10~A0 in the same cycle is the data written
to the mode register. One clock cycle is required to complete the write in the mode register (refer to
the following figure). The contents of the mode register can be changed using the same command
and the clock cycle requirements during operation as long as all banks are in the idle state.
Preliminary
11
Rev 1.4
Oct. 2005
ETRON [ ETRON TECHNOLOGY, INC. ]
