1
Standard Products
UT28F256 Radiation-Hardened 32K x 8 PROM
Data Sheet
December 2002
FEATURES
q Programmable, read-only, asynchronous, radiation-
hardened, 32K x 8 memory
-
Supported by industry standard programmer
q 45ns and 40ns maximum address access time (-55
o
C to
+125
o
C)
q TTL compatible input and TTL/CMOS compatible output
levels
q Three-state data bus
q Low operating and standby current
-
Operating: 125mA maximum @25MHz
Derating: 3mA/MHz
-
Standby: 2mA maximum (post-rad)
q Radiation-hardened process and design; total dose
irradiation testing to MIL-STD-883, Method 1019
-
Total dose: 1E6 rad(Si)
- LET
TH
(0.25) ~ 100 MeV-cm
2
/mg
- SEL Immune >128 MeV-cm
2
/mg
- Saturated Cross Section cm
2
per bit, 1.0E-11
- 1.2E-8 errors/device-day, Adams 90% geosynchronous
heavy ion
-
Memory cell LET threshold: >128 MeV-cm
2
/mg
q QML Q & V compliant part
-
AC and DC testing at factory
q Packaging options:
-
28-lead 50-mil center flatpack (0.490 x 0.74)
-
28-lead 100-mil center DIP (0.600 x 1.4) - contact factory
q V
DD
: 5.0 volts
+
10%
q Standard Microcircuit Drawing 5962-96891
PRODUCT DESCRIPTION
The UT28F256 amorphous silicon anti-fuse PROM is a high
performance, asynchronous, radiation-hardened,
32K x 8 programmable memory device. The UT28F256 PROM
features fully asychronous operation requiring no external clocks
or timing strobes. An advanced radiation-hardened twin-well
CMOS process technology is used to implement the UT28F256.
The combination of radiation-hardness, fast access time, and low
power consumption make the UT28F256 ideal for high speed
systems designed for operation in radiation environments.
DECODER
MEMORY
ARRAY
SENSE AMPLIFIER
PROGRAMMING
CONTROL
LOGIC
DQ(7:0)
A(14:0)
CE
PE
OE
Figure 1. PROM Block Diagram
2
DEVICE OPERATION
The UT28F256 has three control inputs: Chip Enable (CE),
Program Enable (PE), and Output Enable (OE); fifteen address
inputs, A(14:0); and eight bidirectional data lines, DQ(7:0). CE
is the device enable input that controls chip selection, active, and
standby modes. Asserting CE causes I
DD
to rise to its active value
and decodes the fifteen address inputs to select one of 32,768
words in the memory. PE controls program and read operations.
During a read cycle, OE must be asserted to enable the outputs.
PIN NAMES
Table 1. Device Operation Truth Table
1
Notes:
1. "X" is defined as a "don't care" condition.
2. Device active; outputs disabled.
ABSOLUTE MAXIMUM RATINGS
1
(Referenced to V
SS
)
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.
2 . Test per MIL-STD-883, Method 1012, infinite heat sink.
A14
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
V
SS
V
DD
PE
A13
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
PIN CONFIGURATION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
A(14:0)
Address
CE
Chip Enable
OE
Output Enable
PE
Program Enable
DQ(7:0)
Data Input/Data Output
OE
PE
CE
I/O MODE
MODE
X
1
1
Three-state
Standby
0
1
0
Data Out
Read
1
0
0
Data In
Program
1
1
0
Three-state
Read
2
SYMBOL
PARAMETER
LIMITS
UNITS
V
DD
DC supply voltage
-0.3 to 7.0
V
V
I/O
Voltage on any pin
-0.5 to (V
DD
+ 0.5)
V
T
STG
Storage temperature
-65 to +150
C
P
D
Maximum power dissipation
1.5
W
T
J
Maximum junction temperature
+175
C
JC
Thermal resistance, junction-to-case
2
3.3
C/W
I
I
DC input current
10
mA
3
RECOMMENDED OPERATING CONDITIONS
DC ELECTRICAL CHARACTERISTICS (Pre/Post-Radiation)*
(V
DD
= 5.0V
10%; -55
C < T
C
< +125
C)
Notes:
* Post-radiation performance guaranteed at 25
C per MIL-STD-883 Method 1019 at 1E6 rad(Si).
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.
4. Functional test.
5. Derates at 3.0mA/MHz.
SYMBOL
PARAMETER
LIMITS
UNITS
V
DD
Positive supply voltage
4.5 to 5.5
V
T
C
Case temperature range
-55 to +125
C
V
IN
DC input voltage
0 to V
DD
V
SYMBOL
PARAMETER
CONDITION
MINIMUM
MAXIMUM
UNIT
V
IH
High-level input voltage
(TTL)
2.4
V
V
IL
Low-level input voltage
(TTL)
0.8
V
V
OL1
Low-level output voltage
I
OL
= 4.0mA, V
DD
= 4.5V (TTL)
0.4
V
V
OL2
Low-level output voltage
I
OL
= 200
A, V
DD
= 4.5V (CMOS)
V
SS
+ 0.10
V
V
OH1
High-level output voltage
I
OH
= -200
A, V
DD
= 4.5V (CMOS)
V
DD
-0.1
V
V
OH2
High-level output voltage
I
OH
= -2.0mA, V
DD
= 4.5V (TTL)
2.4
V
C
IN
1
Input capacitance
= 1MHz, V
DD
= 5.0V
V
IN
= 0V
15
pF
C
IO
1, 4
Bidirectional I/O capacitance
= 1MHz, V
DD
= 5.0V
V
OUT
= 0V
15
pF
I
IN
Input leakage current
V
IN
= 0V to V
DD
-5
5
A
I
OZ
Three-state output leakage
current
V
O
= 0V to V
DD
V
DD
= 5.5V
OE = 5.5V
-10
10
A
I
OS
2,3
Short-circuit output current
V
DD
= 5.5V, V
O
= V
DD
V
DD
= 5.5V, V
O
= 0V
-90
90
mA
mA
I
DD1
(OP)
5
Supply current operating
@25.0MHz (40ns product)
@22.2MHz (45ns product)
TTL inputs levels (I
OUT
= 0), V
IL
=
0.2V
V
DD
, PE = 5.5V
125
117
mA
mA
I
DD2
(SB)
post-rad
Supply current standby
CMOS input levels V
IL
= V
SS
+0.25V
CE = V
DD
- 0.25 V
IH
= V
DD
- 0.25V
2
mA
4
READ CYCLE
A combination of PE greater than V
IH
(min), and CE less than
V
IL
(max) defines a read cycle. Read access time is measured
from the latter of device enable, output enable, or valid address
to valid data output.
An address access read is initiated by a change in address inputs
while the chip is enabled with OE asserted and PE deasserted.
Valid data appears on data output, DQ(7:0), after the specified
t
AVQV
is satisfied. Outputs remain active throughout the entire
cycle. As long as device enable and output enable are active, the
address inputs may change at a rate equal to the minimum read
cycle time.
The chip enable-controlled access is initiated by CE going active
while OE remains asserted, PE remains deasserted, and the
addresses remain stable for the entire cycle. After the specified
t
ELQV
is satisfied, the eight-bit word addressed by A(14:0)
appears at the data outputs DQ(7:0).
Output enable-controlled access is initiated by OE going active
while CE is asserted, PE is deasserted, and the addresses are
stable. Read access time is t
GLQV
unless t
AVQV
or t
ELQV
have
not been satisfied.
AC CHARACTERISTICS READ CYCLE (Post-Radiation)*
(V
DD
= 5.0V
10%; -55
C < T
C
< +125
C)
Notes:
* Post-radiation performance guaranteed at 25
C per MIL-STD-883 Method 1019 at 1E6 rads(Si).
1. Functional test.
2. Three-state is defined as a 400mV change from steady-state output voltage.
SYMBOL
PARAMETER
28F256-45
MIN MAX
28F256-40
MIN MAX
UNIT
t
AVAV
1
Read cycle time
45
40
ns
t
AVQV
Read access time
45
40
ns
t
AXQX
2
Output hold time
0
0
ns
t
GLQX
2
OE-controlled output enable time
0
0
ns
t
GLQV
OE-controlled access time
15
15
ns
t
GHQZ
OE-controlled output three-state time
15
15
ns
t
ELQX
2
CE-controlled output enable time
0
0
ns
t
ELQV
CE-controlled access time
45
40
ns
t
EHQZ
CE-controlled output three-state time
15
15
ns
5
RADIATION HARDNESS
The UT28F256 PROM incorporates special design and layout
features which allow operation in high-level radiation
environments. UTMC has developed special low-temperature
processing techniques designed to enhance the total-dose
radiation hardness of both the gate oxide and the field oxide while
maintaining the circuit density and reliability. For transient
radiation hardness and latchup immunity, UTMC builds all
radiation-hardened products on epitaxial wafers using an
advanced twin-tub CMOS process. In addition, UTMC pays
special attention to power and ground distribution during the
design phase, minimizing dose-rate upset caused by rail collapse.
RADIATION HARDNESS DESIGN SPECIFICATIONS
1
Note:
1 . The PROM will not latchup during radiation exposure under recommended operating conditions.
Figure 2. PROM Read Cycle
t
AVAV
t
AVQV
t
ELQV
t
GLQV
t
AVQV
t
AXQX
t
EHQZ
t
GHQZ
A(14:0)
CE
OE
DQ(7:0)
t
GLQX
t
ELQX
Total Dose
1E6
rad(Si)
Latchup LET Threshold
>128
MeV-cm
2
/mg
Memory Cell LET Threshold
>128
MeV-cm
2
/mg
Transient Upset LET Threshold
54
MeV-cm
2
/mg
Transient Upset Device Cross Section @ LET=128 MeV-cm
2
/mg
1E-6
cm
2
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