V58C2128(804/404/164)S
Write Interrupted by a Read
A Burst Write can be interrupted by a Read command to any bank. If a burst write operation is interrupted
prior to the end of the burst operation, then the last two pieces of input data prior to the Read command must
be masked off with the data mask (DM) input pin to prevent invalid data from being written into the memory
array. Any data that is present on the DQ pins coincident with or following the Read command will be masked
off by the Read command and will not be written to the array. The memory controller must give up control of
both the DQ bus and the DQS bus at least one clock cycle before the read data appears on the outputs in
order to avoid contention. In order to avoid data contention within the device, a delay is required (tCDLR) from
the last valid data input before a Read command can be issued to the device. It is illegal to interrupt a Write
with autoprecharge command with a Read command.
Write Interrupted by a Read Command Timing
(CAS Latency = 2; Burst Length = 8)
T0
T1
T2
T3
T4
T5
T6
T7
T8
T9
T10
T11
T12
CK, CK
Command
DQS
Write
NOP
NOP
Read
NOP
NOP
D
NOP
NOP
NOP
NOP
NOP
t
WTR
D
D
D
D
D
D
D
D
D
D
D
D
D
7
DQ
0
1
2
3
4
5
0
1
2
3
4
5
6
DM
Data is masked
by DM input
Data is masked
by Read command
DQS input ignored
Auto Refresh
The Auto Refresh command is issued by having CS, RAS, and CAS held low with CKE and WE high at the
rising edge of the clock. All banks must be precharged and idle for a tRP(min) before the Auto Refresh com-
mand is applied. No control of the address pins is required once this cycle has started because of the internal
address counter. When the Auto Refresh cycle has completed, all banks will be in the idle state. A delay be-
tween the Auto Refresh command and the next Activate command or subsequent Auto Refresh command
must be greater than or equal to the tRFC(min). Commands may not be issued to the device once an Auto
Refresh cycle has begun. CS input must remain high during the refresh period or NOP commands must be
registered on each rising edge of the CK input until the refresh period is satisfied.
Auto Refresh Timing
T0
T1
T2
tRP
T3
T4
T5
T6
T7
tRFC
T8
T9
T10
T11
CK, CK
Pre All
Auto Ref
NOP
NOP
NOP
ANY
Command
High
CKE
V58C2128(804/404/164)S Rev. 1.6 March 2002
23
MOSEL [ MOSEL VITELIC, CORP ]
