UL635H256
Advanced Information
Low Voltage PowerStore 32K x 8 nvSRAM
Description
Features
automatically on power up. The
UL635H256 combines the high per-
formance and ease of use of a fast
SRAM with nonvolatile data inte-
grity.
STORE cycles also may be initiated
under user control via a software
sequence.
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.
RECALL cycles may also be initia-
ted by a software sequence.
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 UL635H256 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 UL635H256 is a fast static
RAM (45 and 55 ns), with a nonvo-
latile 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 operation) take place
automatically upon power down
using charge stored in system
capacitance. Transfers from the
EEPROM to the SRAM (the
RECALL operation) take place
High-performance CMOS non-
volatile static RAM 32768 x 8 bits
45 and 55 ns Access Times
20 and 25 ns Output Enable
Access Times
ICC = 8 mA at 200 ns Cycle Time
Automatic STORE to EEPROM
on Power Down using system
capacitance
Software initiated STORE
Automatic STORE Timing
105 STORE cycles to EEPROM
10 years data retention in
EEPROM
Automatic RECALL on Power Up
Software RECALL Initiation
Unlimited RECALL cycles from
EEPROM
Wide voltage range: 2.7 ... 3.6 V
Operating temperature range:
0 to 70 °C
-40 to 85 °C
CECC 90000 Quality Standard
ESD characterization according
MIL STD 883C M3015.7-HBM
Packages: SOP28 (330 mil)
TSOP32 (Type I)
Pin Configuration
Pin Description
G
A11
A9
1
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
n.c.
A10
E
VCC
W
A13
A8
A9
A11
G
A10
E
DQ7
DQ6
DQ5
DQ4
DQ3
A14
A12
A7
A6
A5
A4
A3
A2
A1
A0
1
2
3
4
5
6
7
8
9
10
28
27
26
25
24
23
22
21
20
19
18
17
16
15
Signal Name Signal Description
2
3
A0 - A14
Address Inputs
Data In/Out
A8
4
DQ7
DQ6
DQ5
DQ4
DQ3
VSS
DQ2
DQ1
DQ0
A0
A13
W
n. c.
VCC
n. c.
A14
A12 11
A7
A6
5
DQ0 - DQ7
6
7
Chip Enable
E
8
SOP
TSOP
9
Output Enable
Write Enable
Power Supply Voltage
Ground
G
10
W
12
13
DQ0 11
DQ1
DQ2 13
VSS
VCC
VSS
12
A5 14
A4
A3
A1
15
16
A2
14
n.c.
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271
December 12, 1997