Rev. 1.0, 09/01, page 198 of 904
Note, however, the next continuous synchronous DRAM space access is a full access if:
•
a refresh operation is initiated in the RAS down state
•
self-refreshing is performed
•
the chip enters software standby mode
•
the external bus is released
•
the BE bit is cleared to 0
•
the mode register of the synchronous DRAM is set
There is synchronous DRAM in which time of the active state of each bank is restricted. If it is not
guaranteed that other row address are accessed in a period in which program execution ensures the
value (software standby, sleep, etc.), auto refresh or self refresh must be set, and the restrictions of
the maximum active state time of each bank must be satisfied. When refresh is not used, programs
must be developed so that the bank is not in the active state for more than the specified time.
T
p
Address bus
External address
Column address
Column address 2
External address
Row
address
Column
address
Data bus
T
r
T
c1
T
cl
T
c2
T
c1
T
c2
Continuous synchronous
DRAM space read
Continuous synchronous
DRAM space read
External
space read
T
2
T
cl
T
1
CKE
High
PALL
ACTV READ
NOP
NOP
READ
DQMU, DQML
Precharge-sel
Row
address
ø
Figure 6.53 Example of Operation Timing in RAS Down Mode
(BE = 1, CAS Latency 2)
Содержание H8S/2376 F-ZTAT
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