IC42S32200
IC42S32200L
T0
T1
T2
T3
T4
T5
T6
T7
T8
CLK
COMMAND
READ A
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
CAS# latency=2
t CK2 , DQ s
CAS# latency=3
t CK3 , DQ s
DOUT A0
DOUT A1
DOUT A2
DOUT A3
DOUT A0
DOUT A1
DOUT A2
DOUT A3
Burst Read Operation(Burst Length =4,CAS#Latency =2,3)
The read data appears on the DQs subject to the values on the DQM inputs two clocks earlier (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).
T0
T1
T2
T3
T4
T5
T6
T7
T8
CLK
COMMAND
READ A
READ B
NOP
NOP
NOP
NOP
NOP
NOP
NOP
CAS# latency=2
t CK2 , DQ s
CAS# latency=3
t CK3 , DQ s
DOUT A0
DOUT B0
DOUT B1
DOUT B2
DOUT B3
DOUT A 0
DOUT B0
DOUT B1
DOUT B2
DOUT B3
Read Interrupted by a Read (Burst Length =4,CAS#Latency =2,3)
The DQM inputs are used to avoid I/O contention on the DQ pins when the interrupt comes 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.
Integrated Circuit Solution Inc.
DR036-0D 02/04/2005
9
ICS [ INTEGRATED CIRCUIT SYSTEMS ]
