NTE2708
Integrated Circuit
NMOS, 8K UV EPROM, 450ns
Description:
The NTE2708 is an ultraviolet lighterasable, electrically programmable read only memory. It has
8, 192 bits organized as 1024 words of 8bit length. This device is fabricated using Nchannel silicon
gate technology for high speed and simple interface with MOS and bipolar circuits. All inputs (includ-
ing program data inputs) can be driven by Series 74 TTL circuits without the use of external pullup
resistors. Each output can drive one Series 74 or 74LS TTL circuit without external resistors. The
data outputs for the NTE2708 are threestate for OR tying multiple devices on a common bus.
This EPROM is designed for highdensity fixed memory applications where fast turn arounds and/or
program changes are required. This device is designed for operation from 0
to +70
C and is supplied
in a 24Lead DIP package for insertion in mountinghole rows on 600mil (15.2 mm) centers.
Features:
D
1024 X 8 Organization
D
All Inputs and Outputs Fully TTL Compatible
D
Static Operation (No Clocks, No Refresh)
D
Performance Ranges:
Max Access: 450ns
Min Cycle: 450ns
D
3State Outputs for ORTies
D
8Bit Output
D
PlugCompatible PinOuts Allowing Interchangeability
Absolute Maximum Ratings: (T
A
= 0
to +70
C, Note 1 unless otherwise specified)
Supply Voltage, V
CC
(Note 2)
0.3 to +15V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supply Voltage, V
DD
(Note 2)
0.3 to +20V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supply Voltage, V
SS
(Note 2)
0.3 to +15V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
All Input Voltage (except program) (Note 2)
0.3 to +20V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Program Input (Note 2)
0.3 to +35V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Voltage (operating, with respect to V
SS
)
2 to +7V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating freeair temperature range
0
C to 70
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature Range
55
C to 125
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Note 1. Stresses beyond those listed under "Absolute Maximum Ratings" may cause permenant
damage to the device. This is a stress rating only and functional operation of the device at
these or any other conditions beyond those indicated in the "Recommended Operating
Conditions" section of this specification is not implied. Exposure to absolutemaximum
rated conditions for extended periods may affect device reliability.
Note 2. Under absolute maximum ratings, voltage values are with respect to the mostnegative sup-
ply voltage, V
BB
(substrate), unless otherwise noted. Throughout the remainder of this data
sheet, voltage values are with respect to V
SS
.
Operation (Read Mode):
Address (A0A9)
The addressvalid interval determines the device cycle time. The 10bit positivelogic address is
decoded onchip to select one of the 1024 words of 8bit length in the memory array. A0 is the least
significant bit and A9 is the mostsignificant bit of the words address.
Chip Select, Program Enable [CS (PE)]
When the chip select is low, all eight outputs are enabled and the eightbit addressed word can be
read. When the chip select is high, all eight outputs are in a highimpedance state.
Data Out (Q1Q8)
The chip must be selected before the eightbit outputs word can be read. Data will remain valid until
the address is changed or the chip is deselected. When deselected, the threestate outputs are in
a highimpedance state. The outputs will drive TTL circuits without external components.
Program
The program pin must be held below V
CC
in the read mode.
Operation (Program Mode):
Erase
Before programming, the NTE2708 is erased by exposing the chip through the transparent lid to high
intensity ultraviolet light (wavelength 2537 angstroms). The recommended minimum exposure dose
(= UV intensity x exposure time) is fifteen wattseconds per square centimeter. Thus, a typical 12
milliwatt per square centimeter, filterless UV lamp will erase the device in a minimum of 21 minutes.
The lamp should be located about 2.5 centimeters above the chip during erasure. After erasure, all
bits are in the "1" state.
Programming
Programming consists of successively depositing a small amount of charge to a selected memory cell
that is to be changed from the erased high state to the low state. A low can be changed to a high only
by erasure. Programming is normally accomplished on a PROM or EPROM Programmer. Program-
ming must be done at room temperature (+25
C) only.
To Start Programming
First bring the CS (PE) pin to +12V to disable the outputs and convert them to inputs. This pin is held
high for the duration of the programming sequence. The first word to be programmed is addressed
(it is customary to begin with the "0" address) and the data to be stored is placed on the Q1Q8 pro-
gram inputs. Then a +25V program pulse is applied to the program pin. After 0.1 to 1.0 milliseconds
the program pin is brought back to 0V. After at least one microsecond the word address is sequentially
changed to the next location, the new data is set up and the program pulse is applied.
Programming continues in this manner until all words have been programmed. This constitutes one
of N program loop. The entire sequence is then repeated N times with N x t
w(PR)
100 ms. Thus,
if t
w(PR)
= 1 ms; then N = 100, the minimum number of program loops required to program the EPROM.
To Stop Programming
After cycling through the N program loops, the last program pulse is brought to 0V, then Program En-
able [CS (PE)] is brought to V
IL
which takes the device out of the program mode. The data supplied
by the programmer must be removed before the address is changed since the program inputs are now
data outputs and change of address could cause a voltage conflict on the output buffer. Q1Q8 out-
puts are invalid up to 10 microseconds after the program enable pin is brought from V
IH(PE)
to V
IL
.
Recommended Operating Conditions:
Parameter
Symbol
Min
Nom
Max
Unit
Supply Voltage
V
BB
4.75
5
5.25
V
V
CC
4.75
5
5.25
V
V
DD
11.4
12
12.6
V
V
SS
0
V
HighLevel Input Voltage (Except Program & Program Enable)
V
IH
2.4
V
CC
+1
V
HighLevel Program Enable Input Voltage
V
IH(PE)
11.4
12
12.6
V
HighLevel Program Input Voltage
V
IH(PR)
25
26
27
V
LowLevel Input Voltage (Except Program)
V
IL
V
SS
0.65
V
LowLevel Program Input Voltage V
IL
(PR) max
V
IH
(PR) 25V
V
IL(PR)
V
SS
1
V
HighLevel Program Pulse Input Current (Sink)
I
IH(PR)
40
mA
LowLevel Program Pulse Input Current (Source)
I
IL(PR)
3
mA
Operating FreeAir Temperature
T
A
0
70
C
Electrical Characteristics: (T
A
= 0
to +70
C, Note 3 unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max Unit
Highlevel Output Voltage
V
OH
I
OH
= 100
A
3.7
V
Lowlevel Output Voltage
V
OL
I
OH
= 1mA
2.4
V
Input Current (Leakage)
I
I
I
OL
= 1.6mA
0.45
A
Output Current (Leakage)
I
O
CS(PE) = 5V
1
10
A
Supply Current from V
BB
I
BB
T
A
= 70
C
30
45
mA
Supply Current from V
CC
I
CC
All Inputs High, CS(PE) = 5V,
6
10
mA
Supply Current from V
DD
I
DD
T
A
= 0
C (Worst Case)
50
65
mA
Power Dissipation
P
D(AV)
800
mW
Note 3. All typical values are at T
A
= 25
C and nominal voltages.
Capacitance: (T
A
= 0
to +70
C, f = 1MH
Z
, Note 3 unless otherwise specified)
Parameter
Symbol
Min
Typ
Max
Unit
Input Capacitance
C
I
4
6
pF
Output Capacitance
C
O
8
12
pF
Note 3. All typical values are at T
A
= 25
C and nominal voltages.
Switching Characteristics: (T
A
= 0
to +70
C unless otherwise specified)
Parameter
Test Conditions
Min
Typ
Max
Unit
Access Time from Address
C
L
= 100 pF, 1 Series 74 TTL load,
450
ns
Access Time from CS
t
f(CS)
, t
f(ad)
= 20ns
120
ns
Output Invalid from Address Change
0
ns
Output Disable Time (Note 4)
0
120
ns
Read Cycle Time
450
ns
Note 4. Value calculated from 0.5 volt delta to measured output level.
T
A
= +25
C Program Characteristics Over Recommended Supply Voltage Range:
Parameter
Symbol
Min
Typ
Max
Unit
Pulse Width, Program Pulse
t
w(PR)
0.1
1.0
ms
Transition Times (Except Program Pulse)
t
T
20
ns
Transition Times, Program Pulse
t
T(PR)
50
2000
ns
Address Setup Time
t
su(ad)
10
s
Data Setup Time
t
su(da)
10
s
Program Enable Setup Time
t
su(PE)
10
s
Address Hold Time
t
h(ad)
1000
ns
Address Hold Time after Program Input Data Stopped
t
h(ad, da R)
0
ns
Data Hold Time
t
h(da)
1000
ns
Program Enable Hold Time
t
h(PE)
500
ns
Delay Time, CS (PE) Low to Address Change
t
CL, adX
0
ns
V
DD
CS/(PE)
V
BB
V
CC
Pin Connection Diagram
Q7
A9
A0
A3
A4
A5
A2
Q8
A1
A6
1
2
3
4
A7
5
6
7
24
23
22
21
A8
20
19
18
PROGRAM
8
17
Q2
9
16
Q1
Q6
10
15
Q4
Q3
11
14
Q5
12
13
V
SS
.160 (4.06) Max
.520
(13.2)
1
12
24
13
.280 (7.11) Dia UV Window
Glass Sealant
.200 (5.08)
Max
.100 (2.54)
.600 (15.24) Max
Glass
1.290 (32.76) Max
.670
(17.02)
.125
(3.17)
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