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35, 45 and 55ns Access Times
17, 20 and 25ns Output Enable Access
Unlimited Read and Write to
SRAM
Software
STORE
Initiation
Automatic
STORE
Timing
100,000
STORE
cycles to
EEPROM
10 year data retention in
EEPROM
Automatic
RECALL
on Power Up
Software
RECALL
Initiation
Unlimited
RECALL
cycles from
EEPROM
Single 5V
鹵
10% Operation
Available in multiple standard packages
DESCRIPTION
The Simtek STK11C68-M is a fast static
RAM
(35, 45
and 55ns), with a nonvolatile electrically-erasable
PROM
(
EEPROM
) element incorporated in each static memory
cell. The
SRAM
can be read and written an unlimited
number of times, while independent nonvolatile data
resides in
EEPROM
. Data transfers from the
SRAM
to
the
EEPROM
(
STORE
), or from the
EEPROM
to the
SRAM
(
RECALL
) are initiated through software se-
quences. It combines the high performance and ease
of use of a fast
SRAM
with nonvolatile data integrity.
The STK11C68-M is pin compatible with industry stan-
dard
SRAM
s and is available in a 28-pin 300 mil
ceramic DIP or 28-pad LCC package. Commercial and
industrial devices are also available.
LOGIC BLOCK DIAGRAM
EEPROM ARRAY
256 x 256
A
3
A
4
ROW DECODER
PIN CONFIGURATIONS
A
7
A
12
Vcc
NC
W
NC
NC
A
8
A
9
A
11
G
A
10
E
DQ
7
DQ
6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
3
2
A
6
A
5
A
4
A
3
A
2
A
1
A
0
A
0
A
12
4
5
6
7
8
9
10
11
12
1
28 27
26
25
24
23
A
12
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
DQ
0
DQ
1
DQ
2
V
SS
V
CC
W
NC
A
8
A
9
A
11
G
A
10
E
DQ
7
DQ
6
DQ
5
DQ
4
DQ
3
STORE
STATIC RAM
ARRAY
256 x 256
RECALL
A
5
A
6
A
7
A
8
A
9
A
12
DQ
0
DQ
1
DQ
2
DQ
3
DQ
4
DQ
5
DQ
6
DQ
7
TOP VIEW
22
21
20
19
18
DQ
0
DQ
1
13 14 15 16 17
DQ
2
Vss
DQ
3
DQ
4
STORE/
RECALL
CONTROL
28 - LCC
DQ
5
28 - 300 C-DIP
COLUMN I/O
INPUT BUFFERS
PIN NAMES
A
0
- A
12
W
DQ
0
- DQ
7
E
Address Inputs
Write Enable
Data In/Out
Chip Enable
Output Enable
Power (+5V)
Ground
COLUMN DECODER
A
0
A
1
A
2
A
10
A
11
G
G
V
CC
V
SS
E
W
4-31