EM638165 Etron Technology Inc., EM638165 Datasheet - Page 7

• Manufacturer Part Number: EM638165
• Description: 4Mega x 16 Synchronous DRAM (SDRAM)
• Manufacturer: Etron Technology Inc.

CAS# latency=2
t CK2 , DQ's
Preliminary
CL K
COMMAND
CAS# latency=3
t CK3 , DQ's
CLK
COMMAND
CAS# latency=2
t CK2 , DQ's
CAS# latency=3
t CK3 , DQ's
CLK
DQM
COMM AND
DQ's
: "H" or "L"
(i.e. DQM latency is two clocks for output buffers). A read burst without the auto precharge function
may be interrupted by a subsequent Read or Write command to the same bank or the other active
bank before the end of the burst length. It may be interrupted by a BankPrecharge/ PrechargeAll
command to the same bank too. The interrupt coming from the Read command can occur on any
clock cycle following a previous Read command (refer to the following figure).
from a Write command. The DQMs must be asserted (HIGH) at least two clocks prior to the Write
command to suppress data-out on the DQ pins. To guarantee the DQ pins against I/O contention, a
single cycle with high-impedance on the DQ pins must occur between the last read data and the
Write command (refer to the following three figures). If the data output of the burst read occurs at
the second clock of the burst write, the DQMs must be asserted (HIGH) at least one clock prior to
the Write command to avoid internal bus contention.
The read data appears on the DQs subject to the values on the DQM inputs two clocks earlier
The DQM inputs are used to avoid I/O contention on the DQ pins when the interrupt comes
READ A
T0
Read Interrupted by a Read
READ A
NOP
T0
T0
Burst Read Operation
Read to Write Interval
T 1
NOP
READ B
READ A
T 1
T 1
DOUT A 0
T2
NOP
DOUT A 0
NOP
T2
T2
NOP
DOUT A 1
T3
NOP
DOUT A 0
DOUT B 0
T3
T3
(Burst Length = 4, CAS# Latency = 2, 3)
NOP
DOUT A 0
NOP
(Burst Length
(Burst Length = 4, CAS# Latency = 2, 3)
7
DOUT A 1
DOUT A 2
DOUT A 0
T4
NOP
DOUT B 0
NOP
DOUT B 1
T4
T4
NOP
Must be Hi-Z before
the Write Command
DOUT A 3
T5
NOP
DOUT A 2
4, CAS# Latency = 3)
DOUT B 2
T5
NOP
T5
DOUT B 1
NOP
DOUT A 3
T6
NOP
WRITE B
DOUT B 2
DOUT B 3
T6
NOP
T6
DI NB 0
Rev 0.6
T7
EM638165
NOP
T7
T7
NOP
DOUT B 3
DINB 1
NOP
NOP
Feb. 2001
T8
NOP
DI NB 2
NOP
T8
T8