20ns maximum (3.3 volt supply) address access time
Asynchronous operation for compatibility with industry-
standard 512K x 8 SRAMs
TTL compatible inputs and output levels, three-state
bidirectional data bus
Operational environment:
- Total dose: 50 krads(Si)
- SEL Immune 110 MeV-cm
2
/mg
- SEU LET
TH
(0.25) = 52 cm
2
MeV
- Saturated Cross Section 2.8E-8 cm
2
/bit
-<1.1E-9 errors/bit-day, Adams 90% worst case
environment geosynchronous orbit
Packaging:
- 36-lead ceramic flatpack (3.831 grams)
Standard Microcircuit Drawing 5962-99607
- QML Q and V compliant part
INTRODUCTION
The UT8Q512E RadTol product is a high-performance CMOS
static RAM organized as 524,288 words by 8 bits. Easy memory
expansion is provided by an active LOW Chip Enable (E), an
active LOW Output Enable (G), and three-state drivers.
Writing to the device is accomplished by taking Chip Enable (E)
and Write Enable (W) inputs LOW. Data on the eight I/O pins
(DQ
0
through DQ
7
) is then written into the location specified
on the address pins (A
0
through A
18
). Reading from the device
is accomplished by taking Chip Enable (E) and Output Enable
(G) LOW while forcing Write Enable (W) HIGH. Under these
conditions, the contents of the memory location specified by the
address pins will appear on the I/O pins.
The eight input/output pins (DQ
0
through DQ
7
) are placed in a
high impedance state when the device is deselected (E HIGH),
the outputs are disabled (G HIGH), or during a write operation
(E LOW and W LOW).
Clk. Gen.
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
Pre-Charge Circuit
Row Select
Memory Array
1024 Rows
512x8 Columns
I/O Circuit
Column Select
Data
Control
CLK
Gen.
A10
A11
A12
A13
A14
A15
A16
A17
A18
DQ
0
- DQ
7
E
W
G
Figure 1. UT8Q512E SRAM Block Diagram
1
DEVICE OPERATION
A0
A1
A2
A3
A4
E
DQ0
DQ1
V
DD
V
SS
DQ2
DQ3
W
A5
A6
A7
A8
A9
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
NC
A18
A17
A16
A15
G
DQ7
DQ6
V
SS
V
DD
DQ5
DQ4
A14
A13
A12
A11
A10
NC
The UT8Q512E has three control inputs called Chip Enable (E),
Write Enable (W), and Output Enable (G); 19 address inputs,
A(18:0); and eight bidirectional data lines, DQ(7:0). E controls
device selection, active, and standby modes. Asserting E enables
the device, causes I
DD
to rise to its active value, and decodes the
19 address inputs to select one of 524,288 words in the memory.
W 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
1
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. UT8Q512E 20ns SRAM Pinout (36)
PIN NAMES
A(18:0)
DQ(7:0)
E
W
G
V
DD
V
SS
Address
Data Input/Output
Chip Enable
Write Enable
Output Enable
Power
Ground
Notes:
1. “X” is defined as a “don’t care” condition.
2. Device active; outputs disabled.
READ CYCLE
A combination of W greater than V
IH
(min) and E 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 4a, is
initiated by a change in address inputs while the chip is enabled
with G asserted and W deasserted. Valid data appears on data
outputs DQ(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 4b, is initiated by E going active while G remains asserted,
W 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 DQ(7:0).
SRAM read Cycle 3, the Output Enable - Controlled Access in
figure 4c, is initiated by G going active while E is asserted, W
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 W less than V
IL
(max) and E 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 W is less
than V
IL
(max).
Write Cycle 1, the Write Enable - Controlled Access in figure
5a, is defined by a write terminated by W going high, with E
still active. The write pulse width is defined by t
WLWH
when the
write is initiated by W, and by t
ETWH
when the write is initiated
by E. 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 nine bidirectional pins DQ(7:0) to avoid bus
contention.
Write Cycle 2, the Chip Enable - Controlled Access in figure
5b, is defined by a write terminated by E going inactive. The
write pulse width is defined by t
WLEF
when the write is initiated
by W, and by t
ETEF
when the write is initiated by the E going
active. For the W 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 DQ(7:0) to avoid bus contention.
OPERATIONAL ENVIRONMENT
Table 2.Operational Environment
Design Specifications
1
Total Dose
Heavy Ion
Error Rate
2
50
<1.1E-9
krad(Si)
Errors/Bit-Day
Notes:
1. The SRAM will not latchup during radiation exposure under recommended
operating conditions.
2. Adam’s 0% worst case environment, Geosynchronous orbit, 100 mils of
Aluminum.
3
ABSOLUTE MAXIMUM RATINGS
1
(Referenced to V
SS
)
SYMBOL
V
DD
V
I/O
T
STG
P
D
T
J
Θ
JC
I
I
PARAMETER
DC supply voltage
Voltage on any pin
Storage temperature
Maximum power dissipation
Maximum junction temperature
2
Thermal resistance, junction-to-case
DC input current
LIMITS
-0.5 to 7.0V
-0.5 to 7.0V
-65 to +150°C
1.0W
+150°C
10°C/W
±
10 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.
RECOMMENDED OPERATING CONDITIONS
SYMBOL
V
DD
T
C
V
IN
PARAMETER
Positive supply voltage
Case temperature range
DC input voltage
LIMITS
3.0 to 3.6V
(C) screening: -55°C to +125°C
(W) screening: -40°C to +125°C
0V to V
DD
4
DC ELECTRICAL CHARACTERISTICS (Pre/Post-Radiation)*
-55°C to +125°C for (C) screening and -40
o
C to +125
o
C for (W) screening (V
DD
= 3.3V + 0.3V)
SYMBOL
V
IH
V
IL
V
OL1
V
OL2
V
OH1
V
OH2
C
IN1
C
IO1
I
IN
I
OZ
PARAMETER
High-level input voltage
Low-level input voltage
Low-level output voltage
Low-level output voltage
High-level output voltage
High-level output voltage
Input capacitance
Bidirectional I/O capacitance
Input leakage current
(TTL)
(TTL)
I
OL
= 6mA, V
DD
= 3.0V (TTL)
I
OL
= 200μA,V
DD
= 3.0V (CMOS)
I
OH
= -3mA,V
DD
= 3.0V (TTL)
I
OH
= -200μA,V
DD
= 3.0V (CMOS)
ƒ
= 1MHz @ 0V
ƒ
= 1MHz @ 0V
V
IN
= V
DD
and V
SS,
V
DD
= V
DD
(max)
-2
-2
2.4
V
DD
-
0.10
10
12
2
2
CONDITION
MIN
2
0.8
0.4
0.08
MAX
UNIT
V
V
V
V
V
V
pF
pF
μA
μA
Three-state output leakage current V
O
= V
DD
and V
SS
V
DD
= V
DD
(max)
G = V
DD
(max)
I
OS2, 3
I
DD
(OP)
4
Short-circuit output current
V
DD
= V
DD
(max), V
O
= V
DD
V
DD
= V
DD
(max), V
O
= 0V
Inputs: V
IL
= 0.8V,
V
IH
= 2.0V
I
OUT
= 0mA
V
DD
= V
DD
(max)
Inputs: V
IL
= 0.8V,
V
IH
= 2.0V
I
OUT
= 0mA
V
DD
= V
DD
(max)
Inputs: V
IL
= V
SS
I
OUT
= 0mA
E = V
DD
- 0.5
V
DD
= V
DD
(max)
V
IH
= V
DD
- 0.5V
-55°C,
-40°C, 25°C
125°C
-90
90
mA
Supply current operating
@ 1MHz
50
mA
I
DD
(OP)
4
Supply current operating
@50MHz
76
mA
I
DD
(SB)
5
Supply current standby
@0MHz
10
mA
45
mA
Notes:
* Post-radiation performance guaranteed at 25°C per MIL-STD-883 Method 1019.
1. Measured only for initial qualification and after process or design changes that could affect input/output capacitance.
2. Supplied as a design limit but not guaranteed or tested.
3. Not more than one output may be shorted at a time for maximum duration of one second.
据外媒报道，萨里大学（University of Surrey）的研究人员开发出一种无需依赖GPS即可在人口密集的城市地区精确定位设备位置的人工智能系统。该系统可将定位误差从734米缩小到22米以内，这对于自动驾驶汽车和救援车辆等技术的发展意义重大。 图片来源： 萨里大学 在发表于《IEEE Robotics and Automation Letters》的论文中，研究人员介绍了PEn...[详细]
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