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參數(shù)資料
| 型號(hào)： | STK25C48-W35 |
| 廠商： | Electronic Theatre Controls, Inc. |
| 英文描述： | 2K X 8 AUTOSTORE NVSRAM |
| 中文描述： | 2K × 8自動(dòng)存儲(chǔ)非易失性SRAM |
| 文件頁數(shù)： | 6/8頁 |
| 文件大小： | 129K |
| 代理商： | STK25C48-W35 |
STK25CA8
August 1999
6-6
The STK25CA8 is a versatile memory module that
provides two modes of operation. The STK25CA8
can operate as a standard 128K x 8
SRAM
. It has a
128K x 8
EEPROM
shadow to which the
SRAM
infor-
mation can be copied, or from which the
SRAM
can
be updated in nonvolatile mode.
NOISE CONSIDERATIONS
Note that the STK25CA8 is a high-speed memory
and so must have a high frequency bypass capaci-
tor of approximately 0.1
μ
F connected between V
and V
SS
, using leads and traces that are as short as
possible. As with all high-speed
CMOS
ICs, normal
careful routing of power, ground and signals will help
prevent noise problems.
SRAM READ
The STK25CA8 performs a
READ
cycle whenever E
and G are low and W is high. The address specified
on pins A
determines which of the 131,072 data
bytes will be accessed. When the
READ
is initiated
by an address transition, the outputs will be valid
after a delay of t
(
READ
cycle #1). If the
READ
is
initiated by E or G, the outputs will be valid at t
ELQV
or
at t
GLQV
, whichever is later (
READ
cycle #2). The data
outputs will repeatedly respond to address changes
within the t
AVQV
access time without the need for tran-
sitions on any control input pins, and will remain valid
until another address change or until E or G is
brought high.
SRAM WRITE
A
WRITE
cycle is performed whenever E and W are
low. The address inputs must be stable prior to
entering the
WRITE
cycle and must remain stable
until either E or W goes high at the end of the cycle.
The data on the common I/O pins DQ
0-7
will be writ-
ten into the memory if it is valid t
before the end
of a W controlled
WRITE
or t
DVEH
before the end of an
E controlled
WRITE
.
It is recommended that G be kept high during the
entire
WRITE
cycle to avoid data bus contention on
the common I/O lines. If G is left low, internal circuitry
will turn off the output buffers t
WLQZ
after W goes low.
AutoStore OPERATION
The STK25CA8 uses the intrinsic system capaci-
tance to perform an automatic store on power down.
As long as the system power supply takes at least
t
STORE
to decay from V
SWITCH
down to 3.6V the
STK25CA8 will safely and automatically store the
SRAM
data in
EEPROM
on power down.
In order to prevent unneeded
STORE
operations,
automatic
STOREs
will be ignored unless at least
one
WRITE
operation has taken place since the most
recent
STORE
or
RECALL
cycle.
POWER-UP RECALL
During power up, or after any low-power condition
(V
< V
), an internal
RECALL
request will be
latched. When V
CC
once again exceeds the sense
voltage of V
SWITCH
, a
RECALL
cycle will automatically
be initiated and will take t
RESTORE
to complete.
If the STK25CA8 is in a
WRITE
state at the end of
power-up
RECALL
, the
SRAM
data will be corrupted.
To help avoid this situation, a 10K Ohm resistor
should be connected either between W and system
V
CC
or between E and system V
CC
.
HARDWARE PROTECT
The STK25CA8 offers hardware protection against
inadvertent
STORE
operation and
SRAM WRITE
s dur-
ing low-voltage conditions. When V
CAP
< V
SWITCH
, all
externally initiated
STORE
operations and
SRAM
WRITE
s are inhibited.
LOW AVERAGE ACTIVE POWER
The STK25CA8 draws significantly less current
when it is cycled at times longer than 50ns. If the
chip enable duty cycle is less than 100%, only
standby current is drawn when the chip is disabled.
The
overall
average
current
STK25CA8
depends
on
1)
CMOS
vs.
TTL
input levels; 2) the duty cycle of
chip enable; 3) the overall cycle rate for accesses;
4) the ratio of
READ
s to
WRITE
s; 5) the operating
temperature; 6) the V
CC
level; and 7) I/O loading.
drawn
following
by
the
the
items:
DEVICE OPERATION
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| STK25C48-W35I | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:2K X 8 AUTOSTORE NVSRAM |
| STK25C48-W45 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:2K X 8 AUTOSTORE NVSRAM |
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| STK25CA8 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:128K x 8 AutoStore nvSRAM CMOS Nonvolatile Static RAM Module |
| STK25CA8-D35 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:128K x 8 AutoStore nvSRAM CMOS Nonvolatile Static RAM Module |
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