U631H16
SoftStore 2K x 8 nvSRAM
Packages: PDIP28 (300 mil)
PDIP28 (600 mil)
Data transfers from the SRAM to
the EEPROM (the STORE opera-
tion), or from the EEPROM to the
SRAM (the RECALL ) operation)
are initiated through software
sequences.
The U631H16 combines the high
performance and ease of use of a
fast SRAM with nonvolatile data
integrity.
Features
SOP28 (300 mil)
SOP24 (300 mil)
High-performance CMOS non-
volatile static RAM 2048 x 8 bits
25, 35 and 45 ns Access Times
12, 20 and 25 ns Output Enable
Access Times
Software STORE Initiation
(STORE Cycle Time < 10 ms)
Automatic STORE Timing
105 STORE cycles to EEPROM
10 years data retention in
EEPROM
Automatic RECALL on Power Up
Software RECALL Initiation
(RECALL Cycle Time < 20 µs)
Unlimited RECALL cycles from
EEPROM
Description
The U631H16 has two separate
modes of operation: SRAM mode
and nonvolatile mode. In SRAM
mode, the memory operates as an
ordinary static RAM. In nonvolatile
operation, data is transferred in
parallel from SRAM to EEPROM or
from EEPROM to SRAM. In this
mode SRAM functions are disab-
led.
Once a STORE cycle is initiated,
further input or output are disabled
until the cycle is completed.
Because a sequence of addresses
is used for STORE initiation, it is
important that no other read or write
accesses intervene in the sequence
or the sequence will be aborted.
Internally, RECALL is a two step
procedure. First, the SRAM data is
cleared and second, the nonvolatile
information is transferred into the
SRAM cells.
The RECALL operation in no way
alters the data in the EEPROM
cells. The nonvolatile data can be
recalled an unlimited number of
times.
The U631H16 is a fast static RAM
(25, 35, 45 ns), with a nonvolatile
Unlimited Read and Write to
SRAM
Single 5 V ± 10 % Operation
Operating temperature ranges:
0 to 70 °C
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 resi-
des in EEPROM.
-40 to 85 °C
CECC 90000 Quality Standard
ESD characterization according
MIL STD 883C M3015.7-HBM
(classification see IC Code
Numbers)
Pin Configuration
Pin Description
28
27
26
25
24
23
22
21
20
19
18
1
VCC
W
n.c.
n.c.
A7
1
2
A7
A6
24
23
22
21
20
19
18
17
16
15
14
13
VCC
A8
2
3
n.c.
A8
Signal Name Signal Description
3
A5
4
A6
A9
A0 - A10
Address Inputs
Data In/Out
4
A4
5
A5
A9
W
5
6
A3
DQ0 - DQ7
A4
n.c.
G
G
PDIP
SOP
28
6
7
A2
A3
A10
E
SOP
24
Chip Enable
E
7
8
A1
A2
A10
E
Output Enable
Write Enable
Power Supply Voltage
Ground
G
8
9
A0
A1
DQ7
DQ6
DQ5
DQ4
DQ3
W
9
10
11
12
13
14
DQ0
DQ1
DQ2
VSS
A0
DQ7
DQ6
DQ5
DQ4
DQ3
VCC
VSS
10
11
12
DQ0
DQ1
DQ2
VSS
17
16
15
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1
December 12, 1997