U631H16
SoftStore
2K x 8 nvSRAM
Features
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High-performance CMOS nonvola-
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Packages: PDIP28 (300 mil)
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tile 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
10
5
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
Unlimited Read and Write to
SRAM
Single 5 V
±
10 % Operation
Operating temperature ranges:
0 to 70 °C
-40 to 85 °C
QS 9000 Quality Standard
ESD characterization according
MIL STD 883C M3015.7-HBM
(classification see IC Code
Numbers)
PDIP28 (600 mil)
SOP28 (300 mil)
SOP24 (300 mil)
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.
The U631H16 is a fast static RAM
(25, 35, 45 ns), 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 resi-
des in EEPROM.
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.
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 nonvola-
tile 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.
Pin Configuration
Pin Description
n.c.
n.c.
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
VSS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
VCC
W
n.c.
A8
A9
n.c.
G
A10
E
DQ7
DQ6
DQ5
DQ4
DQ3
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
VSS
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
VCC
A8
A9
W
G
A10
E
DQ7
DQ6
DQ5
DQ4
DQ3
Signal Name
A0 - A10
DQ0 - DQ7
E
G
W
VCC
VSS
Signal Description
Address Inputs
Data In/Out
Chip Enable
Output Enable
Write Enable
Power Supply Voltage
Ground
PDIP
22
SOP
21
28
20
19
18
17
16
15
SOP
19
24
18
17
16
15
14
13
Top View
Top View
April 20, 2004
1
CYPRESS [ CYPRESS SEMICONDUCTOR ]
