SN54/74LS48
BCD TO 7-SEGMENT
DECODER
The SN54 / 74LS48 is a BCD to 7-Segment Decoder consisting of NAND
gates, input buffers and seven AND-OR-INVERT gates. Seven NAND gates
and one driver are connected in pairs to make BCD data and its complement
available to the seven decoding AND-OR-INVERT gates. The remaining
NAND gate and three input buffers provide lamp test, blanking input/ripple-
blanking input for the LS48.
The circuit accepts 4-bit binary-coded-decimal (BCD) and, depending on
the state of the auxiliary inputs, decodes this data to drive other components.
The relative positive logic output levels, as well as conditions required at the
auxiliary inputs, are shown in the truth tables.
The LS48 circuit incorporates automatic leading and / or trailing edge
zero-blanking control (RBI and RBO). Lamp Test (LT) may be activated any
time when the BI / RBO node is HIGH. Both devices contain an overriding
blanking input (BI) which can be used to control the lamp intensity by varying
the frequency and duty cycle of the BI input signal or to inhibit the outputs.
•
Lamp Intensity Modulation Capability (BI/RBO)
•
Internal Pull-Ups Eliminate Need for External Resistors
•
Input Clamp Diodes Eliminate High-Speed Termination Effects
CONNECTION DIAGRAM DIP
(TOP VIEW)
VCC
16
f
15
g
14
a
13
b
12
c
11
d
10
e
9
D SUFFIX
SOIC
CASE 751B-03
BCD TO 7-SEGMENT
DECODER
LOW POWER SCHOTTKY
J SUFFIX
CERAMIC
CASE 620-09
16
1
16
1
N SUFFIX
PLASTIC
CASE 648-08
16
1
1
B
2
C
3
4
5
6
D
7
A
8
GND
ORDERING INFORMATION
SN54LSXXJ
SN74LSXXN
SN74LSXXD
a
LT BI / RBO RBI
LOGIC DIAGRAM
Ceramic
Plastic
SOIC
A
b
B
INPUT
C
D
d
BLANKING INPUT OR
RIPPLE-BLANKING
OUTPUT
c
OUTPUT
LOGIC SYMBOL
7 1 2 6 3 5
A B C D LT RBI
SN54 / 74LS48
a
b c d
e
BI/
f g RBO
e
13 12 11 10 9 15 14 4
VCC = PIN 16
GND = PIN 8
RIPPLE-BLANKING
INPUT
LAMP-TEST
INPUT
f
g
FAST AND LS TTL DATA
5-59
SN54/74LS48
PIN NAMES
HIGH
A, B, C, D
RBI
LT
BI / RBO
BI
BCD Inputs
Ripple-Blanking (Active Low) Input
Lamp-Test (Active Low) Input
Blanking Input or Ripple-
Blanking Output (Active Low)
Blanking (Active Low) Input
0.5 U.L.
0.5 U.L.
0.5 U.L.
0.5 U.L.
1.2 U.L.
0.5 U.L.
Open-Collector
LOADING
(Note a)
LOW
0.25 U.L.
0.25 U.L.
0.25 U.L.
0.75 U.L.
2(1) U.L.
0.25 U.L.
3.75 (1.25) U.L. (48)
NOTES:
a) Unit Load (U.L.) = 40
µA
HIGH / 1.6 mA LOW
b) Outut current measured at VOUT = 0.5 V
Output LOW drive factor is SN54LS / 74LS48: 1.25 U.L. for Military (54), 3.75 U.L. for Commercial (74).
0
1
2
3
4
5
6
7
8
9
10
11 12
13
14
15
NUMERICAL DESIGNATIONS — RESULTANT DISPLAYS
TRUTH TABLE
SN54 / 74LS48
INPUTS
DECIMAL
OR
FUNCTION
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
BI
RBI
LT
OUTPUTS
LT
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
X
H
L
RBI
H
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
L
X
D
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
X
L
X
C
L
L
L
L
H
H
H
H
L
L
L
L
H
H
H
H
X
L
X
B A
L
L
H
L
H
L
BI / RBO
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L
L
H
a
H
L
H
H
L
H
L
H
H
H
L
L
L
H
L
L
L
L
H
b
H
H
H
H
H
L
L
H
H
H
L
L
H
L
L
L
L
L
H
c
H
H
L
H
H
H
H
H
H
H
L
H
L
L
L
L
L
L
H
d
H
L
H
H
L
H
H
L
H
L
H
H
L
H
H
L
L
L
H
e
H
L
H
L
L
L
H
L
H
L
H
L
L
L
H
L
L
L
H
f
H
L
L
L
H
H
H
L
H
H
L
L
H
H
H
L
L
L
H
g
L
L
H
H
H
H
H
L
H
H
H
H
H
H
H
L
L
L
H
NOTE
1
1
H H
L
L
H
L
H
L
H H
L
L
H
L
H
L
H H
L
L
H
L
H
L
H H
X
L
X
X
L
X
NOTES:
(1) BI/RBO is wired-AND logic serving as blanking input (BI) and/or
ripple-blanking output (RBO). The blanking out (BI) must be open
or held at a HIGH level when output functions 0 through 15 are
desired, and ripple-blanking input (RBI) must be open or at a HIGH
level if blanking of a decimal 0 is not desired. X=input may be HIGH
or LOW.
(2) When a LOW level is applied to the blanking input (forced condition)
all segment outputs go to a LOW level, regardless of the state of any
other input condition.
(3) When ripple-blanking input (RBI) and inputs A, B, C, and D are at
LOW level, with the lamp test input at HIGH level, all segment
outputs go to a HIGH level and the ripple-blanking output (RBO)
goes to a LOW level (response condition).
(4) When the blanking input/ripple-blanking output (BI/RBO) is open or
held at a HIGH level, and a LOW level is applied to lamp-test input,
all segment outputs go to a LOW level.
2
3
4
FAST AND LS TTL DATA
5-60
SN54/74LS48
GUARANTEED OPERATING RANGES
Symbol
VCC
TA
IOH
IOH
IOL
IOL
Supply Voltage
Operating Ambient Temperature Range
Output Current — High
Output Current — High
Output Current — Low
Output Current — Low
a to g
BI / RBO
a to g
BI / RBO
BI / RBO
Parameter
54
74
54
74
54, 74
54, 74
54
74
54
74
Min
4.5
4.75
– 55
0
Typ
5.0
5.0
25
25
Max
5.5
5.25
125
70
– 100
– 50
2.0
6.0
1.6
3.2
Unit
V
°C
µA
µA
mA
mA
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Limits
Symbol
VIH
VIL
VIK
VOH
IO
VOL
VOL
IIH
IIL
IIL
ICC
IOS
Parameter
Input HIGH Voltage
Input LOW Voltage
Input Clamp Diode Voltage
Output HIGH Voltage
Output Current a to g
Output LOW Voltage a to g
Output LOW Voltage
BI / RBO
Input HIGH Current
(Except BI / RBO)
Input LOW Current
(Except BI / RBO)
Input LOW Current BI/ RBO
Power Supply Current
Short Circuit Current BI/ RBO (Note 1)
– 0.3
25
54, 74
74
54, 74
74
2.4
– 1.3
4.2
– 2.0
0.4
0.5
0.4
0.5
20
0.1
– 0.4
– 1.2
38
–2.0
54
74
Min
2.0
0.7
0.8
– 1.5
V
µA
mA
V
V
V
V
µA
mA
mA
mA
mA
mA
Typ
Max
Unit
V
V
Test Conditions
Guaranteed Input HIGH Voltage for
All Inputs
Guaranteed Input LOW Voltage for
All Inputs
VCC = MIN, IIN = – 18 mA
VCC = MIN, IOH = – 50
µA,
VIN = VIH or U.L. per Truth Table
VCC = MIN, VO = 0.85 V
Input Conditioner as for VOH
IOL = 2.0 mA
IOL = 6.0 mA
IOL = 1.6 mA
IOL = 3.2 mA
VCC = MIN, VIH = 2.0 V
VIL = VIL MAX
VCC = MAX, VIH = 2.0 V
VIL = VIL MAX
VCC = MAX, VIN = 2.7 V
VCC = MAX, VIN = 7.0 V
VCC = MAX, VIN = 0.4 V
VCC = MAX, VIN = 0.4 V
VCC = MAX
VCC = MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS
(VCC = 5.0 V, TA = 25°C)
Limits
Symbol
tPHL
tPLH
tPHL
tPLH
Parameter
Propagation Delay Time, HIGH-to-LOW
Level Output from A Input
Propagation Delay Time, LOW-to-HIGH
Level Output from A Input
Propagation Delay Time, HIGH-to-LOW
Level Output from RBI Input
Propagation Delay Time, LOW-to-HIGH
Level Output from RBI Input
Min
Typ
Max
100
100
100
100
Unit
ns
CL = 15 pF, RL = 4.0 kΩ
ns
ns
CL = 15 pF, RL = 6.0 kΩ
ns
Test Conditions
FAST AND LS TTL DATA
5-61
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
