NTE8374
Integrated Circuit
SevenSegment Latch/Decoder/Driver for Common Anode LED's
Description:
The NTE 8374 is a 7segment decoder driver in a 16Lead DIP type package incorporating input
latches and output circuits to directly drive common anode LED displays.
Features:
D
High speed input latches for data storage
D
15mA constant current sink capability to directly drive common anode led displays
D
Increases incandescent display life
D
Active low latch enable for easy interface with MSI circuits
D
Data input loading essentially zero when latch disabled
D
Automatic ripple blanking for suppression of leading and/or trailingedge zeroes.
Input Loading/FanOut:
Description
Pin Name
High
Low
Address (Data) Inputs,
A
0
A
3
1.0
0.25 (Note 1)
Latch Enable Input (Active LOW)
L
E
0.5
0.25
Ripple Blanking Input (Active LOW)
RBI
0.5
0.25
Ripple Blanking as Output (Active LOW)
RBO
1.0
0.5
Ripple Blanking as Input (Active LOW)
RBO
0.75
Constant Current Outputs (Active LOW)
a g
Open Collector
15mA
Note 1. Except Loading is 10
A @ 0.4V when L
E
is HIGH.
Absolute Maximum Ratings:
Input Voltage
0.5V to +5.5V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Current
30mA to +5.0mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltage Applied to Outputs in HIGH State:
Standard TTL
0.5V to V
CC
value
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Collector
0.5V to +7.0V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V
CC
Pin Potential to GND Pin
0.5V to +7.0V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current Applied to Output in LOW State (Max)
twice the rated I
OL
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Temperature Range
65
to +150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ambient Temperature Range Under Bias
55
to +125
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Junction Temperature Range Under Bias
55
to +175
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommended Operating Conditions:
Supply Voltage
+4.75V to +5.25V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Free Air Ambient Temperature
0
C to +70
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Functional Description:
The NTE8374 is a 7segment decoder/driver with latches on the address inputs and active LOW
constant current outputs to drive LEDs directly. This device accepts a 4bit binary code and produces
output drive to the appropriate segments of the 7segment display. It has a decode format which pro-
duces numeric codes "0" through "9" and other codes.
Latches on the four data inputs are controlled by an active LOW Latch Enable, L
E
. When L
E
is LOW,
the state of the outputs is determined by the input data. When L
E
goes HIGH, the last data present
at the inputs is stored in the latches and the outputs remain stable. The L
E
pulse width necessary
to accept and store data can be routed directly from high speed counters and frequency dividers into
the display without slowing down the system clock or providing intermediate data storage.
The latch/decoder combination is a simple system which drives LED displays with multiplexed data
input from MOS time clocks, DVMs, calculator chips, etc. Data inputs are multiplexed while the dis-
plays are in static mode. This lowers component and insertion costs, since several circuitsseven
resistors per display, strobe drivers, a separate display voltage source, and clock failure detect cir-
cuitstraditionally found in multiplexed display systems are eliminated. It also allos low strobing rates
to be used without display flicker.
Another NTE8374 feature is the reduced loading on the data inputs when the Latch Enable is HIGH
(only 10
A typ). This allows many NTE8374s to be driven from a MOS device in multiplex mode with-
out the need for drivers on the data lines. The NTE8374 also provides automatic blanking capability
0060.0300 would be displayed as 60.03. Leadingedge zero suppression is obtained by connecting
the Ripple Blanking Output (RBO) of a decoder to the Ripple Blanking Input (RBI) of the next lower
stage device. The most significant decoder stage should have the RBI input grounded; and since
suppression of the least significant integer zero in a number is not usually desired, the RBI input of
this decoder stage should be left open. A similar procedure for the fractional part of a display will pro-
vide automatic suppression of trailingedge zeros. The RBO terminal of the decoder can be or tied
with a modulating signal via an isolating buffer to achieve duration intensity modulation. A suitable
signal can be generated for this purpose by forming a variable frequency multivibrator with a cross
coupled pair of TTL or DTL gates.
DC Characteristics: (T
A
= 0 to +70
C unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Output Voltage, Applied (OFF)
V
OUT
Separate LED Supply
10
V
Output LOW Current, a g
I
OL
V
CC
= 5V, V
OL
= 3V, T
A
= +25
C
12
18
mA
Output HIGH Current, a g
I
OH
V
CC
= Max, V
OUT
= 5.5V
250
A
Power Supply Current
I
CC
V
CC
= Max, V
IN
= GND, V
OUT
= 3V
50
mA
AC Characteristics: (V
CC
= +5VT
A
= +25
C unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Propagation Delay, A
n
to a g
t
PLH
, t
PHL
C
L
= 15pF, R
L
= 1k
140
ns
Propagation Delay, L
E to a g
t
PLH
, t
PHL
C
L
= 15pF, R
L
= 1k
140
ns
AC Operating Requirements: (V
CC
= +5VT
A
= +25
C unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Setup Time HIGH or LOW, A
n
to L
E
t
s
(H)
75
ns
t
s
(L)
30
ns
Hold Time HIGH or LOW, A
n
to L
E
t
h
(H)
0
ns
t
h
(L)
0
ns
L
E
Pulse Width LOW
t
w
(L)
85
ns
PDF 
ZIP
