EtronTech
EM638325
2Mega x 32 SDRAM
Test Mode field (A8~A7)
·
These two bits are used to enter the test mode and must be programmed to "00" in normal operation.
A8
0
A7
0
Test Mode
normal mode
0
1
Vendor Use Only
Vendor Use Only
1
X
Write Burst Length (A9)
·
This bit is used to select the burst write length.
A9
0
Write Burst Length
Burst
1
Single Bit
9
No-Operation command
(RAS# = "H", CAS# = "H", WE# = "H")
The No-Operation command is used to perform a NOP to the SDRAM which is selected (CS#
is Low). This prevents unwanted commands from being registered during idle or wait states.
10 Burst Stop command
(RAS# = "H", CAS# = "H", WE# = "L")
The Burst Stop command is used to terminate either fixed-length or full-page bursts. This
command is only effective in a read/write burst without the auto precharge function. The terminated
read burst ends after a delay equal to the CAS# latency (refer to the following figure). The
termination of a write burst is shown in the following figure.
T0
T 1
T2
T3
T4
T5
T6
T7
T8
CLK
READ A
NOP
NOP
NOP
COMMAND
NOP
NOP
Burst Stop
DOUT A
NOP
NOP
The burst ends after a delay equal to the CAS# latency.
CAS# latency=2
DOUT A
DOUT A
DOUT A
DOUT A
3
0
1
2
t
, DQ's
CK2
CAS# latency=3
, DQ's
DOUT A
DOUT A
DOUT A
3
0
1
2
t
CK3
＞
Termination of a Burst Read Operation (Burst Length
4, CAS# Latency = 2, 3)
T0
T 1
T2
T3
T4
T5
T6
T7
T8
CLK
NOP
NOP
NOP
COMMAND
NOP
WRITE A
NOP
Burst Stop
don't care
NOP
NOP
CAS# latency= 2, 3
DQ's
DIN A
DIN A
0
DIN A
1
2
Input data for the Write is masked.
Termination of a Burst Write Operation (Burst Length = X, CAS# Latency = 1, 2, 3)
Preliminary
14
Rev 1.4
Oct. 2005
ETRON [ ETRON TECHNOLOGY, INC. ]
