NTE21128
Integrated Circuit
NMOS, 128K (16K x 8) UV EPROM
Description:
The NTE21128 is a 131,072 bit UV erasable and electrically programmable memory EPROM in a
28Lead DIP type package organized as 16,384 words by 8 bits. The transparent lid allows the user
to expose the chip to ultraviolet light to erase the bit pattern. A new pattern can then be written to the
device by following the programming procedure.
Features:
D
Access Time: 250ns
D
Single 5V Supply Voltage
D
Low Standby Current: 40mA Max
D
TTL Compatible During Read and Program
D
Fast Programming Algorithm
D
Programming Voltage: 12V Typ
Absolute Maximum Ratings:
Supply Voltage, V
CC
0.6V to 6.25V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Program Supply, V
PP
0.6V to 14V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A9 Voltage, V
A9
0.6V to 13.5V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input or Output Voltages, V
IO
0.6V to 6.25V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ambient Operating Temperature, T
A
0
to +70
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Under Bias, T
BIAS
10
to +80
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Temperature Range, T
stg
65
to +125
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Note 1. Except for the rating "Operating Temperature Range", stresses above those listed in the
table "Absolute Maximum Ratings" may cause permanent damage to the device. These are
stress ratings only and operation of the device at these or any other conditions above those
indicated in the Operating sections of this specification is not implied. Exposure to Absolute
Maximum Rating conditions for extended periods may affect device reliability.
DC Characteristics (Read Mode and Standby Mode):
(T
A
= 0
to + 70
C, V
CC
= +5V
5%, V
PP
= V
CC
)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Output High Voltage
V
OH
I
OH
= 400
A
2.4
V
Output Low Voltage
V
OL
I
OL
= 2.1mA
0.45
V
Input High Voltage
V
IH
2.0
V
CC
+1
V
Input Low Voltage
V
IL
0.1
0.8
V
Output Leakage Current
I
LO
V
OUT
= 5.25V
10
A
Input Leakage Current
I
LI
V
IN
= 5.25V
10
A
V
CC
Current (Standby)
I
CC1
E = V
IH
25
mA
V
CC
Current (Active)
I
CC2
G = E = V
IL
60
100
mA
V
PP
Current
I
PP1
V
PP
= 5.25V
15
mA
DC Characteristics (Program, Program Verify, and Program Inhibit Modes):
(T
A
= +25
5
C, V
CC
= +5V
5% Note 2, V
PP
= +21V
0.5V)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Input High Voltage
V
IH
2.0
V
CC
+1
V
Input Low Voltage
V
IL
0.1
0.8
V
Input Leakage Current
I
LI
V
IN
= V
IL
or V
IH
10
A
Output High Voltage
V
OH
I
OH
= 400
A
2.4
V
Output Low Voltage
V
OL
I
OL
= 2.1mA
0.45
V
V
CC
Current (Program Inhibit)
I
CC1
E = V
IH
25
mA
V
CC
Current (Program Verify)
I
CC2
100
mA
V
PP
Current (Program)
I
PP2
E = P = V
IL
30
mA
V
PP
Current (Program Verify)
I
PP3
E = V
IL
, P = V
IH
15
mA
V
PP
Current (Program Inhibit)
I
PP4
E = V
IH
15
mA
Note 2. V
CC
= 6V
0.25V for highspeed programming.
AC Characteristics (Read Mode and Standby Mode):
(T
A
= 0
to + 70
C, V
CC
= +5V
5%, V
PP
= V
CC
)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Address to Output Delay
t
ACC
E = G = V
IL
250
ns
CE to Output Delay
t
CE
E = V
IL
250
ns
Output Enable to Output Delay
t
OE
E = V
IL
100
ns
Output Enable High to Output Delay
t
DF
E = V
IL
0
85
ns
Address to Output Hold Time
t
OH
E = G = V
IL
0
ns
Test Conditions:
Input Rise and Fall Times: 20ns
Input Pulse Levels: 0.45V to 2.4V
Timing Measurement Reference Levels:
Inputs: 0.8V and 2.0V
Outputs: 0.8V and 2.0V
AC Characteristics (Program, Program Verify, and Program Inhibit Modes):
(T
A
= +25
5
C, V
CC
= +5V
5%, V
PP
= +21V
0.5V)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Address Setup Time
t
AS
Input Pulse Levels = 0.45V to 2.4V,
2
s
E Setup Time
t
OES
Input Timing Reference
Level = 0.8V and 2V,
2
s
Data Setup Time
t
DS
Output Timing Reference
Level = 0.8V and 2V,
2
s
Address Hold Time
t
AH
Level = 0.8V and 2V,
Input Rise and Fall Times: 20ns
0
s
E Setup Time
t
CES
2
s
Data Hold Time
t
DH
2
s
Chip Enable to Output Float Delay
t
DF
0
130
ns
Data Valid from E
t
OE
150
ns
Program Pulse Width (Note 3)
t
PW
45
50
55
ms
V
PP
Setup Time
t
VS
2
s
Note 3. Initial Program Pulse width tolerance is 1msec
5%.
Test Conditions:
Input Pulse Levels: 0.45V to 2.4V
Input Timing Reference Level: 0.8V and 2.0V
Output Timing Reference Level: 0.8V and 2.0V
Input Rise and Fall Times: 20ns
Capacitance: (T
A
= +25
C, f = 1MHz)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Input Capacitance
C
IN
V
IN
= 0V
4
8
pF
Output Capacitance
C
OUT
V
OUT
= 0V
8
14
pF
Device Operation:
A single 5V power supply is required in the read mode. All inputs are TTL levels except for V
PP
.
Read Mode
The NTE21128 has the following two control functions: Chip Enable (E) is the power control used for
device selection and Output Enable (G) is the output control used to gate data to the output pins, inde-
pendent of device selection.
Address access time (t
AVQV
) is equal to the delay from E to output (t
ELQV
). Data is available at the
outputs after the falling edge of G, assuming that E has been low and the addresses have been stable
for at least t
AVQV
t
GLQV
.
Standby Mode
The standby mode, reducing the maximum active power current from 85mA to 40mA, is achieved by
applying a TTL high signal to the E input. When in the standby mode, the outputs are in a high imped-
ance state, independent of the G input.
Device Operation (Cont'd):
Two Line Output Control
The NTE21128 features a 2 line control function which accommodates the use of multiple memory
connection. The two line control function allows:
a.
the lowest possible memory power dissipation,
b.
complete assurance that output bus contention will not occur.
For the most efficient use of these two control lines, E should be decoded and used as the primary
device selecting function, while G should be made a common connection to all devices in the array
and connected to the READ line from the system control bus.
This ensures that all deselected memory devices are in their low power standby mode and that the
output pins are only active when data is required from a particular memory device.
System Considerations
The power switching characteristics of EPROMs require careful decoupling of the devices. The sup-
ply current (I
CC
) has three segments that are of interest to the system designer: the standby current
level, the active current level, and transient current peaks that are produced by the falling and rising
edges of E. The magnitude of these transient current peaks is dependent on the capacitive and induc-
tive loading of the device at the output. The associated transient voltage peaks can be suppressed
by complying with the two line output control and by properly selecting decoupling capacitors. It is
recommended that a 1
f ceramic capacitor be used on every device between V
CC
and V
SS
. This
should be a high frequency capacitor of low inherent inductance and should be placed as close to the
device as possible. In addition, a 4.7
f bulk electrolytic capacitor should be used between V
CC
and
GND for every eight devices. The bulk capacitor should be located near the power supply connection
point. The purpose of the bulk capacitor is to overcome the voltage drop caused by the inductive ef-
fects of PCB traces.
Programming
When delivered, all bits of the NTE21128 are in the "1" state. Data is introduced by selectively pro-
gramming "0s" into the desired bit locations. Although only "0s" will be programmed, both "1s" and
"0s" can be present in the data word. The only way to change a "0" to a "1" is by ultraviolet light erasure.
The NTE21128 is in the programming mode when the V
PP
input is at 12.5V and E and P are at TTL
low. The data to be programmed is applied 8 bits in parallel to the data output pins. The levels required
for the address and data inputs are TTL.
Fast Programming Algorithm
Fast Programming Algorithm rapidly programs the NTE21128 EPROM using an efficient and reliable
method suited to the production programming environment. Programming reliability is also ensured
as the incremental program margin of each byte is continually monitored to determine when it has
been successfully programmed. The Fast Programming Algorithm utilizes two different pulse types:
initial and overprogram.
The duration of the initial P pulse(s) is 1ms, which will then be followed by a longer overprogram pulse
of length 3ms by n (n is equal to the number of the initial onemillisecond pulses applied to a particular
NTE21128 location), before a correct verify occurs. Up to 25 onemillisecond pulses per byte are
provided for before the over program pulse is applied.
The entire sequence of program pulses and byte verifications is performed at V
CC
= 6V and V
PP
=
12.5V. When the Fast Programming cycle has been completed, all bytes should be compared to the
original data with V
CC
= 5V and V
PP
= 5V.
Device Operation (Cont'd):
Program Inhibit
Programming of multiple NTE21128s in parallel with different data is also easily accomplished. Ex-
cept for E, all like inputs (including G) of the parallel NTE21128 may be common. A TTL low pulse
applied to an NTE21128's E input, with V
PP
= 12.5V, will program that NTE21128> A high level E input
inhibits the other NTE21128s from being programmed.
Program Verify
A verify should be performed on the programmed bits to determine that they were correctly pro-
grammed. The verify is accomplished with G = V
IL
, E = V
IL
, P = V
IH
, and V
PP
at 12.5V.
Erasure Operation:
The erasure characteristic of the NTE21128 is such that erasure begins when the cells are exposed
to light with wavelengths shorter than approximately 4000 angstroms. The recommended erasure
procedure for the NTE21128 is exposure to short wave ultraviolet light which has a wavelength of
2537 angstroms. The integrated dose (i.e. UV intensity x exposure time) for erasure should be a mini-
mum of 15 W sec/cm
2
. The erasure time with this dosage is approximately 15 to 20 minutes using
an ultraviolet lamp with 12000
W/cm
2
power rating. The NTE21128 should be placed within 2.5cm
(1 inch) of the lamp tubes during the erasure. Some lamps have a filter on their tubes which should
be removed before erasure.
CE
OE
PGM
V
CC
Pin Connection Diagram
V
PP
O3
O0
A6
A9
A13
A11
A8
A2
O1
A10
1
2
3
4
A12
A7
5
A5
6
A4
7
A3
8
28
27
26
25
24
23
22
21
9
A1
20
O7
O6
10
A0
11
19
18
O5
12
17
O4
13
O2
16
14
GND
15
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