a high performance, asynchronous, radiation-hardened, 32K x 8
programmable memory device. The UT28F256LVQL 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
UT28F256LVQL. The combination of radiation-hardness, fast
access time, and low power consumption make the
UT28F256LQL ideal for high speed systems designed for
operation in radiation environments.
A(14:0)
DECODER
MEMORY
ARRAY
SENSE AMPLIFIER
CE
PE
OE
PROGRAMMING
CONTROL
LOGIC
DQ(7:0)
Figure 1. PROM Block Diagram
2
DEVICE OPERATION
The UT28F256LVQL 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 CONFIGURATION
PIN NAMES
A(14:0)
CE
OE
PE
DQ(7:0)
Address
Chip Enable
Output Enable
Program Enable
Data Input/Data Output
Table 1. Device Operation Truth Table
1
A14
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
V
SS
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
V
DD
PE
A13
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
Notes:
1. “X” is defined as a “don’t care” condition.
2. Device active; outputs disabled.
OE
X
0
1
1
PE
1
1
0
1
CE
1
0
0
0
I/O MODE
Three-state
Data Out
Data In
Three-state
MODE
Standby
Read
Program
Read
2
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
Thermal resistance, junction-to-case
2
DC input current
LIMITS
-0.3 to 6.0
-0.5 to (V
DD
+ 0.5)
-65 to +150
1.5
+175
3.3
UNITS
V
V
°C
W
°C
°C/W
mA
±
10
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.
3
RECOMMENDED OPERATING CONDITIONS
SYMBOL
V
DD
T
C
V
IN
PARAMETER
Positive supply voltage
Case temperature range
DC input voltage
LIMITS
3.0 to 3.6
-55 to +125
0 to V
DD
UNITS
V
°C
V
DC ELECTRICAL CHARACTERISTICS (Pre/Post-Radiation)*
(V
DD
= 3.0V to 3.6V; -55°C < T
C
< +125°C)
SYMBOL
V
IH
V
IL
V
OL1
V
OL2
V
OH1
V
OH2
C
IN 1
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, all inputs
except PE
Input Capacitance PE
C
IO 1
I
IN
Bidirectional I/O capacitance
ƒ
= 1MHz, V
DD
= 3.3V
V
OUT
= 0V
V
IN
= 0V to V
DD
, all pins except PE
V
IN
= V
DD
, PE only
V
O
= 0V to V
DD
V
DD
= 3.6V
OE = 3.6V
V
DD
= 3.6V, V
O
= V
DD
V
DD
= 3.6V, V
O
= 0V
CMOS input levels (I
OUT
= 0), V
IL
=
0.2V
V
DD
, PE = 3.6V, V
IH
= 3.0V
CMOS input levels V
IL
= V
SS
+0.25V
CE = V
DD
- 0.25 V
IH
= V
DD
- 0.25V
-3
I
OL
= 100µA, V
DD
= 3.0V
I
OL
= 1.0mA, V
DD
= 3.0V
I
OH
= -100µA, V
DD
= 3.0V
I
OH
= -1.0mA, V
DD
= 3.0V
ƒ
= 1MHz, V
DD
= 3.3V
V
IN
= 0V
V
DD
-0.15
V
DD
-0.3
15
CONDITION
MINIMUM
0.7V
DD
0.25V
DD
V
SS
+ 0.05
V
SS
+ 0.10
MAXIMUM
UNIT
V
V
V
V
V
V
pF
20
15
pF
µA
µA
µA
Input leakage current
3
35
20
I
OZ
Three-state output leakage
current
-20
I
OS 2,3
I
DD1
(OP)
4
Short-circuit output current
100
-100
mA
mA
Supply current operating
@15.4MHz (65ns product)
50.0
1.0
mA
mA
I
DD2
(SB)
post-rad
Supply current standby
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. 1.7mA/MHz.
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.
AC CHARACTERISTICS READ CYCLE (Post-Radiation)*
(V
DD
= 3.0V to 3.6V; -55°C < T
C
< +125°C)
SYMBOL
t
AVAV1
t
AVQV
t
AXQX2
t
GLQX2
t
GLQV
t
GHQZ
t
ELQX2
t
ELQV
t
EHQZ
PARAMETER
Read cycle time
Read access time
Output hold time
OE-controlled output enable time
OE-controlled access time
OE-controlled output three-state time
CE-controlled output enable time
CE-controlled access time
CE-controlled output three-state 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.
28F256LV-65
MIN
MAX
65
65
0
0
35
35
0
65
35
UNIT
ns
ns
ns
ns
ns
ns
ns
ns
ns
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 200mV change from steady-state output voltage.
