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Simtek
Simtek

U631H256 Datasheet Preview

U631H256 Datasheet

SoftStore 32K x 8 nvSRAM

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U631H256 pdf
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Not Recommended For New Designs
U631H256
SoftStore 32K x 8 nvSRAM
Features
Description
‡ High-performance CMOS non-
volatile static RAM 32768 x 8 bits
‡ 25 ns Access Times
‡ 10 ns Output Enable Access
Times
‡ Software STORE Initiation
‡ Automatic STORE Timing
‡ 106 STORE cycles to EEPROM
‡ 100 years data retention in
EEPROM
‡ Automatic RECALL on Power Up
‡ Software RECALL Initiation
‡ 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 protection > 2000 V
(MIL STD 883C M3015.7-HBM)
‡ RoHS compliance and Pb- free
Package: SOP28 (330 mil)
The U631H256 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 U631H256 is a fast static RAM
(25 ns), with a nonvolatile electri-
cally erasable PROM (EEPROM)
element incorporated in each static
memory cell. The SRAM can be
read and written an unlimited num-
ber of times, while independent
nonvolatile data resides in
EEPROM. Data transfers from the
SRAM to the EEPROM (the
STORE operation), or from the
EEPROM to the SRAM (the
RECALL operation) are initiated
through software sequences.
The U631H256 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.
The U631H256 is pin compatible
with standard SRAMs.
Pin Configuration
A14
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
VSS
1
2
3
4
5
6
7
8 SOP
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VCC
W
A13
A8
A9
A11
G
A10
E
DQ7
DQ6
DQ5
DQ4
DQ3
Top View
August 15, 2006
STK Control #ML0043
Pin Description
Signal Name
A0 - A14
DQ0 - DQ7
E
G
W
VCC
VSS
Signal Description
Address Inputs
Data In/Out
Chip Enable
Output Enable
Write Enable
Power Supply Voltage
Ground
1 Rev 1.1



Simtek
Simtek

U631H256 Datasheet Preview

U631H256 Datasheet

SoftStore 32K x 8 nvSRAM

No Preview Available !

U631H256 pdf
U631H256
Block Diagram
A5
A6
A7
A8
A9
A11
A12
A13
A14
DQ0
DQ1
DQ2
DQ3
DQ4
DQ5
DQ6
DQ7
Truth Table for SRAM Operations
EEPROM Array
512 x (64 x 8)
STORE
SRAM
Array
RECALL
512 Rows x
64 x 8 Columns
Column I/O
Column Decoder
A0 A1 A2 A3 A4 A10
VCC
VSS
Store/
Recall
Control
VCC
Software
Detect
A0 - A13
G
E
W
Operating Mode
EWG
DQ0 - DQ7
Standby/not selected
H
*
*
Internal Read
LHH
High-Z
High-Z
Read
LHL
Data Outputs Low-Z
* H or L
Write
LL *
Data Inputs High-Z
Characteristics
All voltages are referenced to VSS = 0 V (ground).
All characteristics are valid in the power supply voltage range and in the operating temperature range specified.
Dynamic measurements are based on a rise and fall time of 5 ns, measured between 10 % and 90 % of VI, as well as
input levels of VIL = 0 V and VIH = 3 V. The timing reference level of all input and output signals is 1.5 V,
with the exception of the tdis-times and ten-times, in which cases transition is measured ± 200 mV from steady-state voltage.
Absolute Maximum Ratingsa
Symbol
Min.
Max.
Unit
Power Supply Voltage
VCC -0.5
7V
Input Voltage
VI
-0.3
VCC+0.5
V
Output Voltage
VO
-0.3
VCC+0.5
V
Power Dissipation
Operating Temperature
C-Type
K-Type
PD
Ta
0
-40
1W
70 °C
85 °C
Storage Temperature
Tstg -65
150 °C
a: Stresses greater than those listed under „Absolute Maximum Ratings“ may cause permanent damage to the device. This is a stress
rating only, and functional operation of the device at condition above those indicated in the operational sections of this specification is
not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
STK Control #ML0043
2
Rev 1.1
August 15, 2006


Part Number U631H256
Description SoftStore 32K x 8 nvSRAM
Maker Simtek
Total Page 13 Pages
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