em636165 Etron Technology Inc., em636165 Datasheet - Page 12

• Manufacturer Part Number: em636165
• Description: 1m X 16 Bit Synchronous Dram Sdram
• Manufacturer: Etron Technology Inc.

Etron Confidential
7
8
(RAS# = "H", CAS# = "L", WE# = "L", A11 = “V”, A10 = "H", A0-A7 = Column Address)
the write operation. Once this command is given, any subsequent command can not occur within a
time delay of { (burst length -1) + t
performed in this command and the auto precharge function is ignored.
Mode Register Set command
(RAS# = "L", CAS# = "L", WE# = "L", A11 = “V”, A10 = “V”, A0-A9 = Register Data)
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 A0~A9 and A11 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 both banks are in the idle state.
Write and AutoPrecharge command (refer to the following figure)
CAS# latency=2,3
t
CLK
COMMAND
CK,
Note: The LDQM/UDQM can remain low in this example if the length of the write burst is 1 or 2.
DQ
The Write and AutoPrecharge command performs the precharge operation automatically after
The mode register stores the data for controlling the various operating modes of SDRAM. The
COMMAND
CLK
DQM
ADDRESS
DQ
Burst Write with Auto-Precharge
’
s
t
DAL
=t
Activate
T0
Bank A
WR
WRITE
+t
T0
BANK
COL n
DIN
RP
n
T1
NOP
T1
NOP
DIN
N+1
Write to Precharge
WR
tWR
T2
NOP
BANK(S)
Precharge
+ t
T2
RP
Auto Precharge
12
(min.) } . At full-page burst, only the write operation is
DIN A
T3
Write A
(Burst Length = 2, CAS# Latency = 2, 3)
NOP
0
T3
tRP
T4
DIN A
NOP
NOP
T4
1
T5
Begin AutoPrecharge
Bank can be reactivated at
completion of t
NOP
Activate
T5
ROW
Don’t Care
T6
NOP
t
DAL
T6
NOP
Rev. 3.4
DAL
EM636165
T7
NOP
T8
Activate
Bank A
Apr. 2008