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CMOS Static RAM
256K (32K x 8-Bit)
Features
High-speed address/chip select time
– Military: 25/35/45/55/70/85/100ns (max.)
– Industrial: 25/35ns (max.)
– Commercial: 20/25/35ns (max.) low power only
Low-power operation
Battery Backup operation – 2V data retention
Produced with advanced high-performance CMOS
technology
Input and output directly TTL-compatible
Available in standard 28-pin (300 or 600 mil) ceramic DIP,
28-pin (600 mil) plastic DIP, 28-pin (300 mil) SOJ and
32-pin LCC
Military product compliant to MIL-STD-883, Class B
IDT71256S
IDT71256L
Description
The IDT 71256 is a 262,144-bit high-speed static RAM organized as
32K x 8. It is fabricated using IDT's high-performance, high-reliability
CMOS technology.
Address access times as fast as 20ns are available with power
consumption of only 350mW (typ.). The circuit also offers a reduced power
standby mode. When
CS
goes HIGH, the circuit will automatically go to and
remain in, a low-power standby mode as long as
CS
remains HIGH. In
the full standby mode, the low-power device consumes less than 15µW,
typically. This capability provides significant system level power and
cooling savings. The low-power (L) version also offers a battery backup
data retention capability where the circuit typically consumes only 5µW
when operating off a 2V battery.
The IDT71256 is packaged in a 28-pin (300 or 600 mil) ceramic DIP,
a 28-pin 300 mil SOJ, a 28-pin (600 mil) plastic DIP, and a 32-pin LCC
providing high board level packing densities.
The IDT71256 military RAM is manufactured in compliance with the
latest revision of MIL-STD-883, Class B, making it ideally suited to military
temperature applications demanding the highest level of performance and
reliability.
x
x
x
x
x
x
x
Functional Block Diagram
A
0
A
14
I/O
0
I/O
7
N
O
T
FO R
R EC
N O
EW M
M
D E
ES N
D
IG E
N D
S
V
CC
ADDRESS
DECODER
262,144 BIT
MEMORY ARRAY
GND
INPUT
DATA
CIRCUIT
I/O CONTROL
CS
OE
WE
CONTROL
CIRCUIT
,
2946 drw 01
AUGUST 2000
1
©2000 Integrated Device Technology, Inc.
DSC-2946/8
IDT71256S/L
CMOS Static RAM 256K (32K x 8-Bit)
Military, Commercial, and Industrial Temperature Ranges
Pin Configurations
A
14
A
12
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
I/O
0
I/O
1
I/O
2
GND
1
2
3
4
5
6
7
8
9
28
27
26
25
24
Truth Table
(1)
WE
CS
H
V
HC
L
L
L
OE
X
X
H
L
X
I/O
High-Z
High-Z
High-Z
D
OUT
D
IN
Function
Standby (I
SB
)
Standby (I
SB1
)
Output Disabled
Read Data
Write Data
2946 tbl 02
N
O
T
FO R
R EC
N O
EW M
M
D E
ES N
D
IG E
N D
S
21
20
19
18
17
D28-3
P28-1
D28-1
SO28-5
23
22
10
11
12
13
14
16
15
V
CC
WE
A
13
A
8
A
9
A
11
OE
A
10
CS
I/O
7
I/O
6
I/O
5
I/O
4
I/O
3
X
X
H
H
L
NOTE:
1. H = V
IH
, L = V
IL
, X = Don't care.
2946 drw 02
DIP/SOJ
Top View
Absolute Maximum Ratings
(1)
Symbol
Rating
Com'l.
Ind.
V
TERM
Terminal Voltage
with Respect
to GND
Mil.
Unit
V
-0.5 to +7.0 -0.5 to +7.0 -0.5 to +7.0
INDEX
A
7
A
12
A
1
A
14
NC
V V
CC
A
WE
A
13
T
A
Operating
Temperature
0 to +70
-40 to +85
-55 to +125
o
C
C
4 3
2
A
6
A
5
A
4
A
3
A
2
A
1
A
0
NC
I/O
0
5
1
32 31 30
29
28
27
25
24
22
21
6
7
8
26
9
10
11
L32-1
23
12
13
A
8
A
9
A
11
NC
OE
A
10
CS
I/O
7
I/O
8
T
BIAS
Temperature
Under Bias
-55 to +125 -55 to +125 -65 to +135
o
T
STG
Storage
Temperature
Power
Dissipation
-55 to +125 -55 to +125 -65 to +150
1.0
50
1.0
50
1.0
50
o
C
P
T
W
mA
2946 tbl 03
I
OUT
DC Output Current
14 15 16 17 18 19 20
,
,
2946 drw 03
32-Pin LCC
Top View
NOTE:
1. 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 these or any other conditions 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.
I/O
1
I/O
2
GND
NC
I/O
3
I/O
4
I/O
5
Pin Descriptions
Name
A
0
- A
14
Capacitance
(T
A
= +25°C, f = 1.0MHz)
Symbol
Parameter
(1)
Conditions
V
IN
= 0V
Max.
11
Unit
pF
pF
2946 tbl 04
Description
C
IN
Input Capacitance
I/O Capacitance
Address Inputs
C
I/O
V
OUT
= 0V
11
I/O
0
- I/O
7
CS
WE
OE
GND
V
CC
Data Input/Output
Chip Select
Write Enable
Output Enable
Ground
Power
2946 tbl 01
NOTE:
1. This parameter is determined by device characterization, but is not production
tested.
2
IDT71256S/L
CMOS Static RAM 256K (32K x 8-Bit)
Military, Commercial, and Industrial Temperature Ranges
Recommended Operating
Temperature and Supply Voltage
Grade
Military
Industrial
Commercial
Temperature
-55
O
C to +125
O
C
-40
O
C to +85
O
C
0
O
C to +70
O
C
GND
0V
0V
0V
Vcc
5V ± 10%
5V ± 10%
5V ± 10%
2946 tbl 05
Recommended DC Operating
Conditions
Symbol
V
CC
GND
V
IH
V
IL
Parameter
Supply Voltage
Ground
Input High Voltage
Input Low Voltage
Min.
4.5
0
2.2
-0.5
(1)
Typ.
5.0
0
____
Max.
5.5
0
6.0
0.8
Unit
V
V
V
V
2946 tbl 06
DC Electrical Characteristics
(1,2)
(V
CC
= 5.0V ± 10%, V
LC
= 0.2V, V
HC
= V
CC
- 0.2V)
71256S/L20
71256S/L25
71256S/L35
71256S/L45
Mil.
Unit
mA
135
115
20
3
mA
Power
S
L
Com'l.
____
Symbol
I
CC
N
O
T
FO R
R EC
N O
EW M
M
D E
ES N
D
IG E
N D
S
____
NOTE:
1. V
IL
(min.) = –3.0V for pulse width less than 20ns, once per cycle.
Mil.
____
Parameter
Com'l
& Ind
____
Mil.
150
Com'l.
& Ind
____
Mil.
140
Com'l.
____
Dynamic Operating Current
CS
< V
IL
, Outputs Open
V
CC
= Max., f
MAX
(2)
135
____
____
115
____
130
20
3
105
____
120
20
3
____
I
SB
Standby Power Supply Current
(TTL Level),
CS
> V
IH
, V
CC
= Max.,
Outputs Open, f = f
MAX
(2)
S
L
____
____
3
____
3
3
____
I
SB1
Full Standby Power Supply Current
(CMOS Level),
CS
> V
HC
,
V
CC
= Max., f = 0
S
L
____
____
____
20
____
20
____
20
mA
0.4
____
0.4
1.5
0.4
1.5
____
1.5
2946 tbl 07
71256S/L55
Mil.
135
115
20
3
71256S/L70
Mil.
135
115
20
3
71256S/L85
Mil.
135
115
20
3
71256S/L100
Mil.
135
115
20
3
Unit
mA
Symbol
I
CC
Parameter
Power
S
L
Dynamic Operating Current
CS
< V
IL
, Outputs Open
V
CC
= Max., f
MAX
(2)
I
SB
Standby Power Supply Current
(TTL Level),
CS
> V
IH
, V
CC
= Max.,
Outputs Open, f = f
MAX
(2)
S
L
mA
I
SB1
Full Standby Power Supply Current
(CMOS Level),
CS
> V
HC
,
V
CC
= Max., f = 0
S
L
20
20
20
20
mA
1.5
1.5
1.5
1.5
2946 tbl 08
NOTES:
1. All values are maximum guaranteed values.
2. f
MAX
= 1/t
RC
, all address inputs are cycling at f
MAX
; f = 0 means no address pins are cycling.
6.42
3
IDT71256S/L
CMOS Static RAM 256K (32K x 8-Bit)
Military, Commercial, and Industrial Temperature Ranges
AC Test Conditions
Input Pulse Levels
Input Rise/Fall Times
Input Timing Reference Levels
Output Reference Levels
AC Test Load
GND to 3.0V
5ns
1.5V
1.5V
See Figures 1 and 2
2946 tbl 09
DC Electrical Characteristics
(V
CC
= 5.0V ± 10%)
Symbol
|I
LI
|
Parameter
Test Conditions
Min.
____
____
N
O
T
FO R
R EC
N O
EW M
M
D E
ES N
D
IG E
N D
S
5V
5V
480Ω
480Ω
DATA
OUT
DATA
OUT
255Ω
30pF*
255Ω
5pF*
,
,
2946 drw 04
2946 drw 05
Figure 1. AC Test Load
Figure 2. AC Test Load
(for t
CLZ
, t
OLZ
, t
CHZ,
t
OHZ
, t
OW
, and t
WHZ
)
*Includes scope and jig capacitances
IDT71256S
Typ.
____
____
IDT71256L
Typ.
____
____
Max.
10
5
10
5
Min.
____
____
Max.
5
2
5
2
Unit
µA
µA
V
Input Leakage Current
V
CC
= Max.,
V
IN =
GND to V
CC
MIL.
COM"L & IND.
MIL.
COM"L & IND.
|I
LO
|
Output Leakage Current
V
CC
= Max.,
CS
= V
IH
,
V
OUT
= GND to V
CC
____
____
____
____
____
____
____
____
V
OL
Output Low Voltage
I
OL
= 8mA, V
CC
= Min.
____
____
0.4
0.5
____
____
____
0.4
0.5
____
I
OL
= 10mA, V
CC
= Min.
I
OH
= -4mA, V
CC
= Min.
____
____
____
____
V
OH
Output High Voltage
2.4
____
2.4
____
V
2946 tbl 10
Data Retention Characteristics Over All Temperature Ranges
(L Version Only) (V
LC
= 0.2V, V
HC
= V
CC
- 0.2V)
Typ.
(1)
V
CC
@
Max.
V
CC
@
Symbol
Parameter
Test Condition
____
Min.
2.0
____
____
2.0V
____
3.0V
____
2.0V
____
3.0V
____
Unit
V
µA
ns
V
DR
V
CC
for Data Retention
I
CCDR
t
CDR
Data Retention Current
Chip Deselect to Data
Retention Time
Operation Recovery Time
CS
> V
HC
MIL.
COM'L. & IND.
____
____
____
____
500
120
____
800
200
____
0
t
RC
(2)
____
____
t
R
(3)
____
____
____
____
ns
2946 tbl 11
NOTES:
1. T
A
= +25°C.
2. t
RC
= Read Cycle Time.
3. This parameter is guaranteed by device characterization, but is not production tested.
4
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