Asynchronous operation for compatibility with industry-
standard 512K x 8 SRAMs
CMOS compatible inputs and output levels, three-state
bidirectional data bus
- I/O Voltage 3.3 volts, 1.8 volt core
Operational environment:
- Intrinsic total-dose: 300 krad(Si)
- SEL Immune >100
- LET
th
(0.25): 53.0 MeV-cm
2
/mg
- Memory Cell Saturated Cross Section 1.67E-7cm
2
/bit
- Neutron Fluence: 3.0E14n/cm
2
- Dose Rate
- Upset 1.0E9 rad(Si)/sec
- Latchup 1.0E11 rad(Si)/sec
Packaging options:
- 68-lead ceramic quad flatpack (20.238 grams with lead
frame)
Standard Microcircuit Drawing 5962-04227
- QML Q & V compliant part
MeV-cm
2
/mg
INTRODUCTION
The UT8CR512K32 is a high-performance CMOS static RAM
multi-chip module (MCM), organized as four individual
524,288 words by 8 bit SRAMs with common output enable.
Easy memory expansion is provided by active LOW chip
enables (En), an active LOW output enable (G), and three-state
drivers. This device has a power-down feature that reduces
power consumption by more than 90% when deselected.
Writing to each memory is accomplished by taking the
corresponding chip enable (En) input LOW and write enable
(Wn) input LOW. Data on the I/O pins is then written into the
location specified on the address pins (A
0
through A
18
). Reading
from the device is accomplished by taking the chip enable (En)
and output enable (G) LOW while forcing write enable (Wn)
HIGH. Under these conditions, the contents of the memory
location specified by the address pins will appear on the I/O pins.
The input/output pins are placed in a high impedance state when
the device is deselected (En HIGH), the outputs are disabled (G
HIGH), or during a write operation (En LOW and Wn LOW).
Perform 8, 16, 24 or 32 bit accesses by making Wn along with
En a common input to any combination of the discrete memory
die.
E3
A(18:0)
G
W3
E2
W2
E1
W1
W0
E0
512K x 8
512K x 8
512K x 8
512K x 8
DQ(31:24)
or
DQ3(7:0)
DQ(23:16)
or
DQ2(7:0)
DQ(15:8)
or
DQ1(7:0)
DQ(7:0)
or
DQ0(7:0)
Figure 1. UT8CR512K32 SRAM Block Diagram
1
V
DD1
A0
A1
A2
A3
A4
A5
E2
V
SS
E3
W0
A6
A7
A8
A9
A10
V
DD2
DEVICE OPERATION
DQ0(2)
DQ1(2)
DQ2(2)
DQ3(2)
DQ4(2)
DQ5(2)
DQ6(2)
DQ7(2)
V
SS
DQ0(3)
DQ1(3)
DQ2(3)
DQ3(3)
DQ4(3)
DQ5(3)
DQ6(3)
DQ7(3)
DQ0(0)
DQ1(0)
DQ2(0)
DQ3(0)
DQ4(0)
DQ5(0)
DQ6(0)
DQ7(0)
V
SS
DQ0(1)
DQ1(1)
DQ2(1)
DQ3(1)
DQ4(1)
DQ5(1)
DQ6(1)
DQ7(1)
68 67 66 65 64 63 62 61 60 59 58 57 56 555453 52
1
51
2
50
3
49
4
48
5
47
Top View
6
46
7
45
8
44
9
43
10
42
11
41
12
40
13
39
14
38
15
37
16
36
17
35
1819 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
V
DD2
A11
A12
A13
A14
A15
A16
E0
G
E1
A17
W1
W2
W3
A18
V
DD1
V
SS
Each die in the UT8CR512K32 has three control inputs called
Chip Enable (En), Write Enable (Wn), and Output Enable (G);
19 address inputs, A(18:0); and eight bidirectional data lines,
DQ(7:0). The chip enable (En) controls device selection, active,
and standby modes. Asserting En enables the device, causes I
DD
to rise to its active value, and decodes the 19 address inputs to
each memory die by selecting the 2,048,000 byte of memory.
Wn controls read and write operations. During a read cycle, G
must be asserted to enable the outputs.
Table 1. Device Operation Truth Table
G
X
X
1
0
W
X
0
1
1
E
1
0
0
0
I/O Mode
3-state
Data in
3-state
Data out
Mode
Standby
Write
Read
2
Read
Figure 2. 17ns SRAM Pinout 68)
PIN NAMES
A(18:0)
DQ(7:0)
En (4:1)
Wn (4:1)
G
V
DD1
V
DD2
V
SS
Address
Data Input/Output
Chip Enable
Write Enable
Output Enable
Power (1.8V)
Power (3.3V)
Ground
Notes:
1. “X” is defined as a “don’t care” condition.
2. Device active; outputs disabled.
READ CYCLE
A combination of Wn greater than V
IH
(min) with En and G less
than V
IL
(max) defines a read cycle. Read access time is
measured from the latter of Chip Enable, Output Enable, or valid
address to valid data output.
SRAM read Cycle 1, the Address Access, in Figure 3a, is
initiated by a change in address inputs while and chip is enabled
with G asserted and Wn deasserted. Valid data appears on data
outputs DQn(7:0) after the specified t
AVQV
is satisfied. Outputs
remain active throughout the entire cycle. As long as Chip
Enable and Output Enable are active, the address inputs may
change at a rate equal to the minimum read cycle time (t
AVAV
).
SRAM read Cycle 2, the Chip Enable-controlled Access, in
Figure 3b, is initiated by En going active while G remains
asserted, Wn remains deasserted, and the addresses remain
stable for the entire cycle. After the specified t
ETQV
is satisfied,
the eight-bit word addressed by A(18:0) is accessed and appears
at the data outputs DQn(7:0).
SRAM read Cycle 3, the Output Enable-controlled Access, in
Figure 3c, is initiated by G going active while En is asserted,
Wn is deasserted, and the addresses are stable. Read access time
is t
GLQV
unless t
AVQV
or t
ETQV
have not been satisfied.
2
WRITE CYCLE
A combination of Wn less than V
IL
(max) and En less than
V
IL
(max) defines a write cycle. The state of G is a “don’t care”
for a write cycle. The outputs are placed in the high-impedance
state when either G is greater than V
IH
(min), or when Wn is less
than V
IL
(max).
Write Cycle 1, the Write Enable-controlled Access is defined
by a write terminated by Wn going high, with En still active.
The write pulse width is defined by t
WLWH
when the write is
initiated by Wn, and by t
ETWH
when the write is initiated by En.
Unless the outputs have been previously placed in the high-
impedance state by G, the user must wait t
WLQZ
before applying
data to the eight bidirectional pins DQn(7:0) to avoid bus
contention.
Write Cycle 2, the Chip Enable-controlled Access is defined by
a write terminated by the former of En or Wn going inactive.
The write pulse width is defined by t
WLEF
when the write is
initiated by Wn, and by t
ETEF
when the write is initiated by the
En going active. For the Wn initiated write, unless the outputs
have been previously placed in the high-impedance state by G,
the user must wait t
WLQZ
before applying data to the eight
bidirectional pins DQn (7:0) to avoid bus contention.
Operational Environment
The UT8CR512K32 SRAM incorporates special design and
layout features which allows operation in a limited environment.
Table 2. Operational Environment
Design Specifications
1
Total Dose
Heavy Ion
Error Rate
2
300K
8.9x10
-10
rad(Si)
Errors/Bit-Day
Notes:
1. The SRAM is immune to latchup to particles >100MeV-cm
2
/mg.
2. 90% worst case particle environment, Geosynchronous orbit, 100 mils of
Aluminum.
Supply Sequencing
No supply voltage sequencing is required between V
DD1
and
V
DD2
.
3
ABSOLUTE MAXIMUM RATINGS
1
(Referenced to V
SS
)
SYMBOL
V
DD1
V
DD2
V
I/O
T
STG
P
D
T
J
Θ
JC
I
I
PARAMETER
DC supply voltage
DC supply voltage
Voltage on any pin
Storage temperature
Maximum power dissipation
Maximum junction temperature
2
Thermal resistance, junction-to-case
3
DC input current
LIMITS
-0.3 to 2.1V
-0.3 to 3.8V
-0.3 to 3.8V
-65 to +150°C
1.2W
+150°C
5°C/W
±
5 mA
Notes:
1. Stresses outside the listed 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 beyond limits indicated in the operational sections of this specification is not recommended. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability and performance.
2. Maximum junction temperature may be increased to +175°C during burn-in and steady-static life.
3. Test per MIL-STD-883, Method 1012.
RECOMMENDED OPERATING CONDITIONS
SYMBOL
V
DD1
V
DD2
T
C
PARAMETER
Positive supply voltage
Positive supply voltage
Case temperature range
LIMITS
1.7 to 1.9V
1
3.0 to 3.6V
(P) Screening: 25°C
(C) Screening: -55 to +125°C
(W) Screening: -40 to +125°C
0V to V
DD2
V
IN
DC input voltage
Notes:
1. For increased noise immunity, supply voltage (V
DD1
) can be increased to 2.0V. If not tested, all applicable DC and AC characteristics are guaranteed by characterization
at V
DD1
(max) = 2.0V.
4
DC ELECTRICAL CHARACTERISTICS (Pre and Post-Radiation)*
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